Human Motion Evaluation



Human Motion Evaluation

Lower Body Kinematics Laboratory

Project #8: Final Report

14:650:486 Design of Mechanical Systems

Group members: William Barrett

William Castroman

Charles Fox

Rich Lin

Erick Silvestre

Advisor: Professor Noshir Langrana

December 8th, 2003

Executive Summary

Typical lab setups for interactive human motion capture have very high costs and are usually unaffordable by an engineering department seeking to evenly disperse its funds among all its majors. This project will succeed in developing an interactive human motion lab, focusing specifically on the lower body, while minimizing cost through innovative techniques and an adherence to a strict budget. The best way to accomplish this task is to have a balance in the design. Rather than purchasing a previously designed lab with equipment that can cost thousands of dollars, this laboratory has equipment and parts purchased from outside sources as well as built within Rutgers. This lab seeks to offer the biomechanical engineering department at Rutgers as well as other universities across the country an affordable yet effective lab option for its students.

Table of contents Page

|Problem Description and Mission Statement |4 |

|Significance |5 |

|Background |6 |

|Design Specifications |10 |

|Concept Development |14 |

|Project Management |19 |

|Model Development |24 |

|Design Synthesis |25 |

|Design Analysis |27 |

|Final CAD Drawings |28 |

|List of Components |28 |

|Design of Safety Features |31 |

|Discussion and Conclusion |32 |

|List of References |34 |

|Appendices |35 |

| | |

Problem Description and Mission Statement

Biomechanical engineering is a recently implemented major-option in the mechanical engineering program and many of the learning tools required for each student to fully understand biomechanics are yet to be applied. The most appropriate method of developing each student’s knowledge of biomechanics is through hands on experience, such as laboratory experiments. It is imperative that students understand how dynamic human motion and kinematics relate. Unfortunately, such lab setups for interactive human motion capture can cost up to $250,000. With each engineering department competing for their share of the annual budget, receiving such a large sum of money is very difficult.

The goal of this project is to develop a senior bio-option lab to evaluate the human motion in a possible rehabilitation or recreational environment and to design, fabricate and evaluate a realistic, functional lab set-up while maintaining a budget of $3000. Specifically, the focus of the lab will not be on the whole body, but a specific part in order to gain an in depth understanding of that area. That focus can be directed in two general directions, the upper and the lower body. After establishing the goal previously stated, the focus of the lab turned towards the lower body. The students will evaluate the kinematics and forces on the knee and understand its roles in bicycling by collecting data, analyzing the range of motion with the motion capture devices, performing calculations and deriving the formulas and equations of motion.

The mission of the team is to create an effective, affordable and interactive biomechanical laboratory experiment demonstrating the fundamentals of human motion. The laboratory experiment will employ motion capture and force displacement by combining hardware and software devices to perform data collection, analysis and presentation of the lower body. The complete design process includes the lab set up, purchasing or fabricating equipment, deriving the equations of motion, and the lab procedure, which includes the student lab manual and the teaching assistant’s solution guide.

Significance

The number of biomedical engineering jobs will increase by 31.4% through 2010 - double the rate of all other jobs combined according to the US Department of Labor. Overall engineering jobs will grow by 9.4% through the end of the decade1. Health services, engineering management, and other services are expected to account for almost half of all non-farm wage and salary jobs through 2010. These numbers give rise to the increased education in the field of biomedical engineering and the importance of this project; a biomechanical laboratory for undergraduate mechanical engineering majors seeking the bio-mechanics option.

The price of laboratory equipment can be exceedingly high for a biomechanical education application. The School of Engineering at Rutgers University funds all the lab experiments by charging each engineering student a $500 laboratory fee, which covers the cost of new equipment, maintenance and facilities. In order to most effectively and efficiently spend these funds, the biomechanics program cannot justify spending up to $100,000 for equipment that only has one application.

This project will give the department an affordable laboratory option that will aid in their students in learning at the university. Independently, the equipment, experiments, and research that exist on the market and in the academic world will not fulfill the hands-on laboratory experience that a student needs. This lower body motion evaluation will combine those three articles and combine them to provide an effective learning tool. The equipment purchased or created as a result of this laboratory can potentially be used in other lab experiments in the engineering department as well.

Background

The Muscles

Body motion evaluation is a vital part of recreation, rehabilitation, injury prevention and physical fitness assessment. In cycling, a majority of the activity occurs in the lower body, which refers to all the muscles from the hip and lower. Although the specific details of the responsibilities of each muscle will not be covered in this lab, it will be beneficial for the students and the teaching assistants in charge of the lab to know what muscles are involved (the lab manual will direct the students to resources for background reading).

Figures 1 and 2 show the major leg muscles in the leg2.

[pic] [pic]

Figure 1: Front view of the lower body. Figure 2: Rear view of the lower body.

3In the power phase, the rectus femoris, part of the quadriceps, is the driving force and generates a tangential pedal force and a kinematic moment and contributes to the motion of the knee (the dynamics and motion of the lower body will be discussed later on in this section). The hamstrings oppose the knee extension and contribute to the motion of the hips. They begin seeing the most activity at the bottom of the pedal stroke when the leg completes its extension and must be pulled up to continue the rotation of the bicycle crank.

Other contributing muscles are the gastrocnemius muscles (calves), which generate the forces required to balance the ankle moment during the power stroke. The tibialis anterior flexes the ankle during the upstroke in preparation of the next thrust. The gluteus maximus provides the normal pedal force and is aided by the inertia of the leg.

The Model

To model the leg, a two-bar linkage in rigid body motion is used. The foot is constrained to move in a given path, which is a circle with the radius equal to the length of the crank on the bicycle. The first point of the link represents the hip and remains stationary, the second point represents the knee joint, and the third point represents the foot. A three-bar linkage is a more accurate representation because an extra point is added to represent the ankle joint. However, the added point creates another angle to include in the calculations and derivations. An even more complicated and exact representation is a five-bar linkage that incorporates segment masses and moments of inertia. Most recently, Redfield and Hull4 used the five bar linkage to determine the static and kinetic contributions of the muscles. For the purpose of simplicity and ease of calculations, the two-bar linkage was used in this lab. Detailed calculations and explanations of the two-bar linkage model are demonstrated in depth in the Model Development and Design Synthesis sections of this report.

Similar Products and Experiments

Many products on the market exist that have similar functions as those involved in this human body motion lab. Many experiments and studies have also been conducted on this topic in different variations. For example, Biodex Medical Systems, a company that designs equipment used in physical medicine and rehabilitation, manufacture an exercise bike that offers different resistances. Isokinetic speed control provides accommodating resistance throughout the cyclist’s entire range of motion for the duration of the exercise period5. The different speed settings, data feedback, ergonomic seats, handlebars and pedals are all optimal qualities this lab requires in an exercise bike.

In terms of motion capture devices many software applications are available on the market in a wide range of prices. Ariel Dynamics has a software program called Ariel Performance Analysis System (APAS) 6. This program video based 3-D motion analysis system that captures video from multiple cameras and then measures, analyzes, and presents movement characteristics. The system models the human body as a mechanical system of moving segments upon which muscular, gravitational, inertial, and reaction forces will be applied, which is a similar process the students will follow in the human motion evaluation lab. APAS is applied to human performance, injury and rehabilitation assessment, equipment and product testing end development, and physical training among many others.

Many universities have done studies on various aspects of bicycling and its relation to the human body. The University of Michigan has conducted numerous biomechanical studies, and one experiment is the “Comparison of the knee joint load on a recumbent vs. stationary bicycle.7” As observed in Figure 3, markers were place on various places on the body in order to observe the movement, positions, and angles at those points during the motion.

[pic]

Figure 3: Placing markers at the joints provide one solution in recording body movements.

The purpose of this experiment was to study and determine whether one form of cycling, recumbent or upright, was more advantageous than the other. In analyzing the movements, they determined which position provided the least load on the knee joint.

A study done by Hull, Neptune, and Boyd of the mechanical engineering department at University of California at Davis also dealt with cycling. Specifically, they measured pedal and knee loads using a multi-degree-of-freedom pedal platform8. The pedal load data was collected simultaneously with the video and encoder data using a six-load component pedal dynamometer. Shear panels acted as the elastic elements and electrical resistance strain gages as transducers. The procedure involved 15 minutes of warm up cycling, then a work rate of 120 W at 90 rpm with four different pedal platforms. The data was collected in ten second increments for 2 minutes, resulting in readings for foot motion (angles) and pedal loads. The conclusion of this experiment was that the multi-degree-of-freedom pedal platform significantly reduced the loads at the pedal, but not at the knee.

Even though many studies have already been conducted about the advantages of biking, it is beneficial for biomechanics students to be able to observe these studies for themselves firsthand. Rather than purchasing expensive equipment to complete this goal, the proposed project requires a reasonable budget and simple setup.

Design Specifications

The design specifications that need to be defined are the exercise bike; the lab area and setup, the data measuring and collection equipment and the motion capture equipment. Safety and cost are important factors in the design aspect of this lab. The total cost of the equipment must not exceed $3000. In addition to the cost, the goal of the design is to acquire the simplest materials and equipment and combine them in such a way that they performed more advanced data collecting and processing functions.

The Lab Area

The nature of the laboratory requires careful planning and design of the area and environment in use. Due to the physical activity involved, the room must have adequate space and ventilation. Students are required to dress appropriately (sneakers, shorts or jogging pants, and t-shirt) if they are planning to participate in the actual riding of the exercise bike. The room must also have sufficient space to accommodate all the equipment, 3-6 students and the instructor comfortably and safely. It is strongly suggested that the room be a minimum of 15 feet in length and 10 feet in width. The room should be properly ventilated and a fan should be used if the room is lacking windows or access to air from an outside source.

The Bike

The bike requires a variable belt resistance for the different force measurements and an adjustable seat to accommodate the different heights and leg lengths of each rider. The footprint of the bike is estimated to be 30”x50,” around 2 ½ x 4 feet. A bike of this size would only occupy 7% of the suggested room dimensions. There is a possibility of using the electromagnetic resistance system due to its advantages over a less advanced belt tension system, since it will improve the workout efficiency. There are also plans of making a more ergonomic and comfortable seat that will provide a stronger back support. Other improvements in consideration are an advanced console system and toe clips to avoid any slippage on the pedals.

The types of resistances in the bike should definitely be considered. The three major types of resistance used are friction, air and magnetic9. In an air resistance exercise bike, an enclosed fan provides the resistance. Air resistance is a cheap and reliable system that provides accumulative resistance, which means that the harder you pedal, the more the resistance. This system would not suit our application because we need a measurable resistance, and the air resistance system does not offer a constant value. Friction bikes are the cheapest of all the bikes and rely on either friction between the flywheel and an adjustable belt or pad. Magnetic resistance bikes are the most expensive but offer the most realistic ride. The resistance is provided by sets of electromagnets placed around the flywheel. A computer via a console usually mounted on the bike can easily control the resistance.

After weighing the characteristics of each type of resistance, the belt tension system was selected. This type of bike fits well into the budget while successfully offer variations of resistance to the rider.

The Equipment

The equipment can be separated into two categories, the data collection and motion capture. These two types of equipment are needed to analyze the forces, kinematics, positions and range of motion of the lower body while riding the bike. To collect the force data, we have pressure transducers mounted on the bicycle pedals to measure the force applied to the pedal by the rider. All the force and speed data collected will be transmitted to a computer connected by wires and processed through a pre-prepared LabView VI.

The original plan to capture the range of motion of the knee was with a charge coupled device (CCD) camera. The camera will be mounted a sufficient distance away from the bike and aim to capture images of the knee at different positions. With these images, the students can observe the angles of the knee and the leg, which will aid in the force calculations. The frame-rate (how many shots the camera takes per second) is set for 30 frames/second for the motion capture. To better capture the images, reflective markers will be used. CCD cameras rely on thousands of tiny pixels to capture light entering through the lens. The reflective markers will make it easier for the camera to pick up the light. After discussing this option with some members of the engineering department, the decision was made to use a digital camcorder already owned by the department. The digital camcorder exceeds the performance of a CCD camera and allows for higher frame-rates. This would eliminate the cost of purchasing a new CCD camera and allow the funds to be directed elsewhere or saved.

Another important component in this lab is the knee brace where the reflective markers will be placed. Wearing a knee brace, instead of placing the markers directly on the rider, will keep the sensors at the same position while the leg is performing the motion. This will help minimize the error when collecting the data. The following picture (Figure 4) shows a possible type of knee brace that could be used.

[pic]

Figure 4

Donjoy Ortho 4titude Knee Brace

The reflective markers aid in the motion capture because they indicate important points on the body that will be used in developing an x, y coordinate system. After the coordinate system is established, calculations for angle and range of motion will be easier.

The software used in the motion capture will be Scion Frame Grabber, which is already owned by the engineering department. The program can capture, display, analyze, enhance, annotate, and display images. The program is used with a Frame Grabber board that collects the images recorded by the camera and inputs them into the Frame Grabber software for analysis.

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Concept Development

The following are a list of proposed concepts, descriptions and sketches for the lab (refer to Appendix A for the sketches).

Running vs. Biking (Figure A1)

This idea involves an exercise bike and a treadmill for the running segment. The point of the lab is to calculate the stress on the knee for both the bike and the running position. To calculate the stress in the knee, force plates will be placed in the treadmill. To calculate the stress in the bike there will be force sensors in the pedals. The end result will be calculated on a computer simulation that will be attached to the Lab view software and comparisons of the two activities will be completed.

Football Kick (Figure A2)

This idea is based on calculating the velocity that the person kicks with and range of motion that the person is experiencing. The position can be calculated using the sensors placed on the person and ultimately read by the strategically placed cameras. One member of the group will perform the action while the rest of the group monitors and collects all the data. This is designed to be a fun yet very useful lab to calculate the kinematics of the knee. A hypothesis will be formed about what technique will bring ultimate trajectory and distance on the kick.

Versatile Kinematic Forcing Equipment (Figure A3)

This sketch was made in the early part of the concept phase. This proposal is a station that will portray all useful qualitative and quantitative information useful to analysis. Then creates a program that allows the viewer to see all useful data and make decisions about the gate cycle of the patient. This would be focused on comprehensive lab equipment that would be able to be used for several lab procedures. This concept was not considered because of price constraints prior to developing the concept matrix.

Soccer Player Motion Evaluation (Figure A4)

This concept evaluates hip, knee, and ankle motion of a soccer player performing a play and ultimately shooting the ball. This evaluation can determine an effective way to create the best output possible when shooting the ball, determine critical loads on the joint, minimize potential injuries, and to keep performance at its highest level. The lab will consist of 3 stations for hip, knee, and ankle evaluation respectively. The ranges of motion in each action (running, dribbling and shooting) are analyzed and the forces on each joint are calculated.

Boxing (Figure A5)

This idea is to measure the force applied to the punching bag and to get the most efficient force applied. The experiment involves analyzing the joint at the shoulder and the elbow. The height with respect to the floor of the point at which the punch makes contact with the bag (the variable y in Figure A5) is taken into consideration. Kinematic equations can be obtained based on how much the bag moves (the variable x in Figure A5) and the number of cycles it undergoes before it comes to a complete stop.

Concept Discussion

The concept that will be further researched is the running vs. biking concept. After debating the issues and rating the concepts, the running and biking scenarios were the most practical due to a number of factors. The money that is allotted for this laboratory is in the range of $2000-3000, which narrows our possibilities in this area. The design needs to be an enjoyable lab that has a high educational value. Safety was also an important parameter in our selection criteria (Refer the following page for Tables 1 and 2). To further narrow down the focus of the lab, biking was the chosen recreational activity because it fit well into the selection criteria. The concept matrix shown in Tables 1 and 2 show the evaluation of both the running and biking concepts and indicate that focusing solely on the activity of biking was the most optimal concept.

| |Concepts |

| | |

| |Bicycle |Boxing |3 station Soccer |Football Kick |Upper extremity |Running (Reference) |

| | | | | |Shoulder Bench Press | |

|1. Ease in Kinematics Calculations |+ |+ |0 |0 |+ |0 |

|2. Price Logistics |+ |+ |- |+ |+ |0 |

|3. Enjoyment Factor |+ |+ |+ |+ |- |0 |

|4. Educational Value |0 |0 |0 |- |0 |0 |

|5. Versatility |0 |- |+ |+ |- |0 |

|6. Product Safety |+ |- |- |- |- |0 |

|7. Durability |+ |- |0 |0 |+ |0 |

| sum +'s |5 |3 |2 |3 |3 |0 |

| sum 0's |2 |1 |3 |2 |1 |7 |

| sum -'s |0 |3 |2 |2 |3 |0 |

| Net Score |5 |0 |0 |1 |0 |0 |

| Rank |1 |3 |3 |2 |3 |3 |

| Continue |yes |No |Revise |Yes |No |No |

Table 1: Concept Matrix for Preliminary Concepts

Table 2: Concept Matrix

| | |Concepts |

| | | |

|Selection Criteria |  |Bicycle |2 station Soccer |Football Kick |Running (Reference) |

|  |Weight |Rating |Weighted Score |Rating |Weighted Score |

| | Rank |  |  |  |  |

| |Continue |  |  |  |  |

| |

|William Barrett |CAD drawings and animation |

| |Equipment Research |

| |Deriving equations of motion |

| |Calculating joint angles |

|William Castroman |Creating lab manual and procedures |

| |Safety |

| |Background and research |

|Charles Fox |Concept development and significance |

| |Project Management |

| |Deriving kinematic equations |

|Rich Lin |Design specifications |

| |Report and background |

| |Website |

|Ericke Silvestre |Market Research |

| |Creating lab manual and procedure |

| |Developing Safety Procedures |

Following tables (Tables 4 and 5) are detailed timelines of the design stage of the project. The testing and development stage will be executed next semester.

Table 4: General Project Management Timeline/Calendar

| |

|Stage 1: Design | |  |

|Week 1 |Understanding the Problem |Establish goals and mission statement|

|  |  |Meet with Prof. Langrana to discuss |

| | |details of the project |

|  |  |Background research on similar |

| | |experiments. |

|  |  |Discuss possible laboratory options |

|Week 2 |Brainstorming |Begin formulating ideas and |

| | |preliminary designs |

|  |  |Each group member creates a concept |

|  |  |Drawings and sketches of concepts |

|Week 3 |Select Concept and Begin Design |Discuss strengths and weaknesses of |

| | |each design |

|  |  |Narrow down choices based on cost, |

| | |safety and educational value |

|  |  |Select final concept for |

| | |implementation |

|  |  |Delegate group responsibilities |

|  |  |Establish a more focused and specific|

| | |goal for the lab. |

|Week 4 |Design |Background research |

|  |  |Equipment research [exercise bikes] |

|  |  |Begin deriving kinematic equations |

|  |  |CAD Drawings |

|Week 5 |Mid-term Presentation |Prepare report and presentation |

|  |  |Complete preliminary design of the |

| | |lab set-up |

|  |  |Compile all current research |

|  |  |Evaluate performance and current |

| | |project status |

|Week 6 |Design |Equipment research and selection |

| | |[motion capture equipment] |

|  |  |CAD Drawings |

|  |  |Derivations of equations |

|  |  |Create price list of all components |

|Week 7 |Design |Complete the derivations and |

| | |calculations |

|  |  |Finalize design of the set-up |

|  |  |Begin writing lab procedure |

|  |  |Equipment research and selection |

| | |[data collecting instruments and |

| | |software] |

|Week 8 |Selecting Components |Select components and compile price |

| | |list |

|  |  |Re-assess goals, improve and simplify|

| | |design to most efficiently use the |

| | |money allotted in the budget |

|  |  |Continue writing the lab manual and |

| | |procedure |

|  |  |Complete CAD Drawings and Animation |

|Week 9 |Finalization |Begin relating CAD drawings, |

| | |equations, and calculations |

|  |  |Complete the Lab Manual and procedure|

|  |  |Begin writing final project report |

|  |  |Finalize design specifications, |

| | |components, and prices |

|Week 10 |Final Presentation |Complete final project report |

|  |  |Complete website |

|  |  |Create presentation |

In the testing and development stage, additional research will be done in the area of force measurement and current sample calculations will be modified. The various equipment options available to us, such as pressure transducers and force plates, will be analyzed and narrowed down and actual equipment will be acquired.

The testing stage will include actually setting up the hardware and software of the lab to test its functionality. Depending on the results of the tests, the layout and equipment may be modified and the set up of the lab finalized. After the design of the equipment and set up are completed, the focus will turn towards the measuring of the data and implementation of the lab. This includes the setting up of the LabView program for the data input and analysis, procedures, integration of the measuring equipment, and force and kinematics calculations. Further familiarization of the data collection software and equipment will be required.

In order to test the lab procedure and manual, trial runs of the lab will be conducted and suggestions for improvement will be considered.

Model Development

[pic]

Figure 5: A flow chart of the structure of the lab set up – the data collection and transfer process.

The motion of the leg during the bicycle exercise can be modeled as a double pendulum, and the equation of motion can be found as follows (Refer to page 26, Figure 6 for diagram):

T is the kinetic energy

V is the potential energy

L is the Lagrange’s Equation

Velocity of Mass 1 = L1 [pic]1

Velocity of Mass 2 = [(L1 [pic]1)2 + (L2 [pic]2)2 + 2L1 L2 [pic]1 [pic]2 Cos ((2 - (1)]1/2

Kinetic Energy:

➢ T = ½ m1 L1 [pic]12 + ½ m2 [(L1 [pic]1)2 + (L2 (2)2 + 2L1 L2 [pic]1 [pic]2 Cos ((2 - (1)]

By letting the Potential Energy (P.E.) = 0 at the origin, we can find the PE (V) of the system:

➢ V = -m1 g L1 Cos (1 - m2 g (L1 Cos (1 + L2 Cos (2) = - (m1 + m2) g L1 Cos (1 - m2 g L2 Cos (2

To develop the equation of motion for the double pendulum system modeling the leg in the bicycle we take the LaGrangian equation as follows:

➢ L = T – V (Difference between KE and PE energies).

➢ (L / ([pic]1 = m1 L12 [pic]1 + m2 L12 [pic]1 + m2 L1 L2 [pic]2 Cos ((2 - (1)

➢ d/dt((L / ([pic]1) = (m1 + m2)L12 [pic]1 + m2 L1 L2 [pic]2 Cos ((2 - (1) - m2 L1 L2 [pic]2 ([pic]2 - [pic]1) Sin((2 - (1)

➢ (L / ((1 = m2 L1 L2 [pic]1 [pic]2 ((2 - (1) - (m1 + m2) g L1 Sin (1

❖ Equation of motion with some cancellations will end up being:

(m1 + m2) L12 [pic]1 + [m2 L1 L2 Cos ((2 - (1)] [pic]2 – [m2 L1 L2 Sin ((2 - (1)] [pic]12 + (m1 + m2) g L1 Sin (1 = 0

❖ Similarly:

➢ (L / ([pic]2 = m2 L22 [pic]2 + m2 L1 L2 [pic]1 Cos ((2 - (1)

➢ d/dt((L / ([pic]2) = m2 L22 [pic]2 + m2 L1 L2 [pic]1 Cos ((2 - (1) - m2 L1 L2 [pic]1 ([pic]2 - [pic]1) Sin((2 - (1)

➢ (L / ((2 = - m2 L1 L2 [pic]1 [pic]2 Sin((2 - (1) - m2 g L2 Sin (2

❖ Equation of motion with some cancellations will end up being:

m2 L22 [pic]2 + [m2 L1 L2 Cos ((2 - (1) ] [pic]1 + [m2 L1 L2 Sin ((2 - (1) ] [pic]22 + m2 g L2 Sin (2 = (2

(m1 + m2) L12 [pic]1 + [m2 L1 L2 Cos ((2 - (1)] [pic]2 – [m2 L1 L2 Sin ((2 - (1)] [pic]22 + (m1 + m2) g L1 Sin (1 = (1

Figure 6: The knee joint modeled as a double pendulum.

Design Analysis

All plots and charts are located in Appendix D.

In order to calculate the necessary data needed for plotting the knee, hip and pedal angles several steps had to be taken to change raw coordinate points into workable data measurements. Several assumptions include the femur length L1=19”, tibia length L2=16”, pedal length L3=8”, the stationary coordinates of the hip h=(4, 24), and by assuming the pedal was traveling at a constant rate of 60RPM. The center of the coordinate axis is the center of pedal rotation. Θ1 indicates the hip angle, θ2 is the knee angle relative to the upper leg, and θ3= the angle of rotation of the pedal. The actual pedal coordinates (x3, y3) could be calculated by using the formula x3=L3 cosθ3, y3=L3 sinθ3. Using the distance formula on these points and the location of the hip calculates L4. Lengths L1, L2, L4 creates a triangle. Now using trigonometric functions on this triangle will evaluate the knee angle θ2 for the complete cycle. Similar formulas are used to calculated θ1, the Hip angle. The results are displayed in three graphs, Angle Vs. Time, Angular Velocity Vs. Time, and Angular Acceleration Vs. Time.

Design Synthesis

Refer to the complete student Lab Manual in Appendix B.

Final CAD Drawings

Refer to Appendix C

List of Components

The components used for the Human Motion Evaluation lab are mostly mainstream commercially available parts. The only elements requiring customization are the bike pedal and the knee brace. In order to allow for force data collection a small force sensor must be integrated into the bike pedal itself. We are currently hoping to simply core out part of the plastic pedal and insert the sensor from underneath, however a custom pedal might need to be fabricated from a piece of aluminum stock and then fitted to the bike. The knee brace simply needs to have the reflective markers attached at three locations, the joint, and at the top and bottom of the brace.

Table 6: List of components and prices

|Component |Source |Cost |

|Upright Exercise Bike | |$199.99 |

|Knee Brace | |$50.00 |

|Pressure Transducer | |$395.00 |

|Signal Conditioners | |$425.00 |

|CCD Camera | |$290.00 |

|Camera Stand | |$40.00 |

|Reflective Markers | |$20.00 |

|Computer |Dell |$400.00 |

|Data Aquistion Software | |$200.00 |

|Tape Measure | |$29.99 |

|Rubber Floor Mat | |$39.99 |

|Scale |body-fat-scales-n-body-fat- |$52.94 |

|Total: |  |$2,142.91 |

The list of components and prices in Table 6 is compiled for a “worse-case scenario,” a case where all necessary equipment for the lab must be purchased. However, this may not be the case since the engineering department at Rutgers University may already own some equipment they are willing to use for this lab like the computer and digital camcorder.

Component Details:

Exercise bike

The Exercise bike sold by sears is manufactured by ProForm. It’s an upright bike utilizing magnetic resistance instead of belt tension. The handles include EKG monitors your heart rate. The control panel displays your speed, time, distance and calories burned. There is also a water bottle holder, necessary to help prevent fatigue during the experiment.

Weight Scale

The scale being used is the Body Fat Scale TBF 679. This model provides measurements in increments of 2 lbs (1kg) and a maximum capacity of 300lbs (136kg). The scale also provides an easy to read digital readout and a rubberized coating to prevent slipping.

Tape Measure

The Starrett D3416 Digitape 3/4" x 16' Electronic Tape Measure will be used to measure leg lengths and any other necessary measurements. The Tape measure has a digital readout on top to assist in the accuracy of measurement. The tape measure may also be zeroed at any blade length.

CCD Camera

The CCD Camera is being purchased from . The CCD camera features 410,000 / 270,000 Pixels, which is much more sensitive then we will require. There is also Variable gamma controls and includes an easy to use on-screen menu and adjustments. The output is variable up to 75 hertz, 75 frames per second.

Data Acquisition Software

The data acquisition software, OrthoTrak, is from . OrthoTrak is a fully automated, three-dimensional, clinical gait measurement, evaluation and database management system. The OrthoTrak System easily integrates kinematic and kinetic analysis with EMG and force plate data. OrthoTrak allows the clinician to easily record the patient's physical measurement data with the gait report, and quickly compile technical data into simple, easy to read, charts and graphs. OrthoTrak is the only clinical package that allows critical upper body measurements (head, trunk, arms, and shoulder kinematics), which compliment lower body kinetics and kinematics.

Floor Mat

In order to prevent damage to the floor from the bike we are getting an Apache Mills Equipment Mat[pic]. The durable, easy to handle mat protects and reduces stress on the floors and carpets. It is 36 in. wide x 72 in. long x 1/4 in. thick, with a textured, slip resistant surface.

Pressure Transducer

Sensotec manufactures the Pressure Sensors being used in the bike pedal. The Model 13 compression-only subminiature load cell is designed to measure load ranges from 50 grams to 250 lbs.  With subminiature dimensions these units are easily incorporated into systems having limited space. The load cell also features a mV/V output.

Signal Conditioner

In order to read the data from the pressure sensor a signal conditioner is required. We are using a signal conditioner from Sensotec. It features a Panel digital Meter along with a full function signal conditioner. It also has an amplifier and power supply that works with non-amplified mV/V transducers.  It provides shunt calibration, which enables the system to be set up without using an expensive primary stimulus

Camera Stand

The stand is necessary to make sure the CCD is placed at the proper height.

Knee Brace

Reflective Markers

Computer

Safety Features

The Human Motion Evaluation Lab follows a relatively simple procedure. However safety is still a concern. Since the products being used are all commercially available they are already manufactured “safe.” In order to create a safe lab environment some precautions have to be made. To prevent any shaking or slipping of the bike while being operated a rubberized mat was place underneath it. Since the mat is six feet long a portion of it will fall behind the bike, this may provide a slight cushion in the event a student should fall backward off the bike. All cords will be run along the wall or taped to the floor to eliminate any tripping hazards while roaming around lab room. None of the components require a power input so electrocution is not a concern except when initially plugging in the devices. Aside from the precautions already mentioned the only other concern would be that the bike is ridden in the proper fashion. Horseplay or destruction of the devices could cause serious, negligent injuries.

Discussion and Conclusion

From competitive cycling in the likes of world-class cycle champion Lance Armstrong to the common recreational biker, analysis of biking to improve performance and decrease the chance for injury is definitely an issue where analysis is needed. The biomechanics laboratory chosen allows students to get a glimpse of cycling analysis while learning a great deal about how mechanical systems and biology come together. The basic knowledge of the mechanics of the lower body gained from the lab is an excellent basis for further study in biomechanics. This design allows the student to complete a simple analysis that provides for maximum learning capabilities while saving thousands of dollars in expensive equipment. Some ways to further improve the lab is to include automation and varying test procedures. Although many varieties of parameters were suggested, such as changing resistances, speeds and acceleration, not all were incorporated into the lab due to time constraints. Automation makes the process of collecting and processing data more efficient. For example, the current design dictates that in order to collect knee and ankle coordinates, the student needs to do it manually by analyzing 60 different images. This is a tedious job for the student, and having software that automatically collects the points acquired eliminates this tedious process.

Extremely useful results are acquired stemming from the equations of motion of a simple pendulum system. Students are asked to derive these equations of motion in their lab write-up. They are then asked to calculate the total torque in the knee from the derived equations and the raw data from the experiment. Students can observe the applications from the final results and ultimately compare them to the actual results from other experiments.

Another advantage to the analysis proposed is that students will view kinematic results on a screen and on paper. The students are required to make plots of the data collected. This graphical representation will be displayed for the position, angular velocity and acceleration curves over time. These values will be calculated using simple geometric representations discussed in detail earlier in this report.

The disadvantages of this laboratory are that the students will analyze the knee in only two-dimensions, whereas a true to life situation requires a three-dimensional analysis to correctly model the behavior in the knee. However, the two-dimensional case provides similar results, so for the purpose of simplicity, this model suffices. Also human error will come into play because the rider needs to keep up a constant pace to get accurate results, especially when they are performing analysis when a constant speed is required.

Given the constraints there are several limitations that could allow for deviation from the complete analysis. The analysis will only be given over one full 360( cycle where as the reality would be an evaluation over a longer period of time to ensure minimum error.

Our future work includes many simulations to ensure that the laboratory will provide the desired results given the equipment that is used. Future improvements may include an analysis of the three dimensional space to be able to see if there are any incorrect movements in another plane of motion. Also a more accurate torque could be revealed given the higher degree of freedom in calculation. A more complicated depiction of the motion in the leg may be needed to prepare the desired results for the system. Variations in the procedure like a viscous dampening, such as wind, can be an interesting addition for students to see what happens to the torque in the knee in different riding conditions.

References

1. “Report on the American Workforce,” US Department of Labor, August 30, 2001,

2. “Muscle Zone – Leg Muscles and Exercises,” Dec. 12th, 2003,

3. Vaughan, Christopher L., “Biomechanics of Sport,” (1989) CRC Press Inc. pp. 269-309.

4. Redfield, R. and Hull, M. L., “On the relation between join moments and pedaling rates at constant power in bicycling” J. Biomech, 1986.

5. “Lower Body Cycle,” December 6, 2003,

6. “APAS” October 18, 2003,

7. “Comparison of the knee joint load on a recumbent vs. upright bicycle.” Motion Analysis Projects, December 6, 2003,

8. Boyd, T.F., Neptune, R.R., and Hull, M.L. (1997). Pedal and knee loads using a multi-degree-of-freedom pedal platform in cycling. Journal of Biomechanics 30(5): 505-511.

9. “Types of Exercise Bikes” October 30, 2003,

10. Susan J. Hall, “Basic Biomechanics,” Appendix D, Anthropometrics parameters for the human body.

11. Meirovitch, Leonard “Fundamentals of Vibrations,” The McGraw-Hill Company inc. New York, NY 2001

Appendix A – Concept Sketches

Appendix B – Student Lab Manual

Human Motion Evaluation

Biomechanical Engineering Laboratory

Rutgers, The State University of New Jersey

Department of Mechanical & Aerospace Engineering

SAFETY

The Human Motion Evaluation Lab follows a relatively simple procedure. However, safety is still a concern. Since the equipment being used is all commercially available, and already manufactured “safe” no hazards should be present. However, in order to ensure a safe lab environment some precautions have to be made. To prevent any shaking or slipping of the bike while being operated, a rubberized mat was place underneath it. Since the mat is six feet long a portion of it will fall behind the bike, this may provide a slight cushion in the event a student should fall backward off the bike. All cords will be run along the wall or taped to the floor to eliminate any tripping hazards while roaming around lab room. None of the components require a power input, so electrocution is not a concern except when initially plugging in the devices. Another concern would be that the bike is ridden in the proper fashion. Horseplay or destruction of the devices could cause serious, negligent injuries. In addition to the above precautions the following safety procedures must be followed:

• Warm up and perform stretches before starting pedaling exercise.

• Utilize clips to prevent slippage from the pedal.

• No loose clothing or items while performing exercise.

• No sandals.

• Fit check card required using bicycle.

ABSTRACT

Bicycles are ubiquitous machines, used throughout the world for locomotion, exercise, sport, and research. Consequently, an understanding of the biomechanics of cycling should be important to those involved with cyclist and to those interested in general biomechanics.

To better understand the goal of this laboratory experiment, one must first understand that pedaling requires the effective transfer of energy from the lower limbs into the pedal. This energy is transferred into the crankshaft, which drives the chain that accelerates the bike. Effective use of force, through the pedal at the correct point in time of the crank cycle is required to achieve the maximum torque. Force is thought to be applied perpendicular to the pedal crankshaft during the down stroke. However, as it will be seen in this laboratory the foot is not completely perpendicular to the pedal crankshaft during down stroke. Also it will be noted that the crankshaft angle will change and the range of the down stroke where the maximum force is applied will change as well. Since pedaling action is a cyclic activity then the recovery phase (upstroke) of cycling requires efficient use of energy through the inertial forces of pedaling action. Energy can be lost through incorrect pedaling angle resulting in reduced effective force.

Other reasons aside from the objective of this laboratory that may encourage the studying of cycling biomechanics are first of all, the reduction of knee injuries caused by cycling, the use of stationary ergo meters for therapy, and improved performance in cycling competitions.

1. OBJECTIVES

The Human Motion Evaluation Lab will allow all students seeking to obtain the biomechanical option to fully understand pressure distribution and motion of the lower part of the body and its main joints as it applies to real world movements. By cycling on the exercise bike the CCD Camera precisely maps out the motion of the hip, knee, and ankle joint while the pressure transducer measures force on the pedal for the entire cycle to provide a measure for the torque. The objective of this laboratory is to allow students to familiarize themselves with the calculation of human body kinematics in the lower part of the body (Femur, Tibia), and to obtain and interpret force data during a simple biking exercise. The exercises performed on this lab to evaluate human motion on lower extremities such as hip, knee, and ankle joint will give the students a better understanding of how the lower body acts during a bicycling activity. The data obtained will yield information on how the joint angles change having a simple 2-D reference frame.

2. BACKGROUND READING

By referring to the site the student will be able to review pedaling in a seated versus standing cycling and get a better feeling on what really affects the total force applied to the crank shaft. By understanding the differences that take place when pedaling in a seated position versus pedaling in standing position, the student will discover that efficient pedaling requires an effective way to transfer energy from the lower limbs of your body into the pedals of the bicycle. What many may not know, is that the energy transfer to pedaling alone will not give you a better efficiency rate, but the correct point in time of the crank cycle is required as well. This could be seen after performing the laboratory calculation and obtaining torque values for different points in the pedaling cycle. By reading through the site provided, and by referring to books in sports biomechanics, Susan J. Hall, Basic Biomechanics, the students will be able to physically see how different angles give different efficiencies for the same amount of energy produced. This information will also be obtained after performing the report calculations for the laboratory exercise.

3. THEORY

The leg can be modeled as a double pendulum as illustrated on Drawing 1 on the next page. By letting m1 be the knee joint with some degree of freedom, and by letting m2 be the ankle joint we are able to calculate the movement of the knee in a simple 2-D (x, y) reference frame. To make the calculations easier we can assume that the hip joint will be stationary for the purpose of the lab and only focus on movements at the knee and at the ankle. Calculations are simplified by seeing that the movement at the ankle is the same movement following the pedal around a circle. In order to obtain equations of motion and kinematics we will need to solve each of our variables.

The variables on Drawing 1 are defined as the following:

• L1 is the Length of the upper leg (Femur).

• L2 is the Length of the lower leg (Tibia).

• L3 is the Length of the pedal Shaft.

• L4 is the Length of the Hip joint to the ankle joint, sum of L1 + L2.

• (1 is the angle between the normal and the upper leg.

• (2 is the angle between the upper and lower leg.

• X is the angle between L4 and the upper leg.

Drawing 2 is a little more elaborated compared to the previous Drawing 1. In this drawing we see the reference frame showing the different joints under consideration. That is, H represents the position of the hip, K the position of the knee, and P the position of the pedal at any given time capture by the CCD during the pedaling cycle. From here, we can then derive formulas for the different joints and the way they change during the completion of a cycle.

Refer to the following formulas to see how to calculate the torque on the pedal mathematically. Keep these values in mind when comparing with the torque provided by the pressure transducer.

In the following equations:

T is the kinetic energy, V is the potential energy, and L is the Langarian Equation. [pic] is the angular velocity, and [pic]is the angular acceleration.

Velocity of Mass 1 = L1 [pic]1

Velocity of Mass 2 = [(L1 [pic]1)2 + (L2 [pic]2)2 + 2L1 L2 [pic]1 [pic]2 Cos ((2 - (1)]1/2

Kinetic Energy:

➢ T = ½ m1 L1 [pic]12 + ½ m2 [(L1 [pic]1)2 + (L2 (2)2 + 2L1 L2 [pic]1 [pic]2 Cos ((2 - (1)]

By letting the Potential Energy (P.E.) = 0 at the origin, we can find the Potential Energy of the system:

➢ V = -m1 g L1 Cos (1 - m2 g (L1 Cos (1 + L2 Cos (2) = - (m1 + m2) g L1 Cos (1 - m2 g L2 Cos (2

To develop the equation of motion for the double pendulum system modeling the leg in the bicycle we

take the Lagrange of KE and PE as follows:

➢ L = T – V (Difference between KE and PE energies).

➢ (L / ( [pic]1 = m1 L12 [pic]1 + m2 L12 [pic]1 + m2 L1 L2 [pic]2 Cos ((2 - (1)

➢ d/dt((L / ( [pic]1) = (m1 + m2)L12 [pic]1 + m2 L1 L2 [pic]2 Cos ((2 - (1) - m2 L1 L2 [pic]2 ([pic]2 - [pic]1) Sin((2 - (1)

➢ (L / ((1 = m2 L1 L2 [pic]1 [pic]2 ((2 - (1) - (m1 + m2) g L1 Sin (1

❖ Equation of motion for knee joint with some cancellations will end up being:

(m1 + m2) L12 [pic]1 + [m2 L1 L2 Cos ((2 - (1)] [pic]2 – [m2 L1 L2 Sin ((2 - (1)] [pic]12 + (m1 + m2) g L1 Sin (1 = 0

❖ Similarly for ankle joint:

➢ (L / ( [pic]2 = m2 L22 [pic]2 + m2 L1 L2 [pic]1 Cos ((2 - (1)

➢ d/dt((L / ( [pic]2) = m2 L22 [pic]2 + m2 L1 L2 [pic]1 Cos ((2 - (1) - m2 L1 L2 [pic]1 ([pic]2 - [pic]1) Sin((2 - (1)

➢ (L / ((2 = - m2 L1 L2 [pic]1 [pic]2 Sin((2 - (1) - m2 g L2 Sin (2

❖ Finally equation of motion at knee and ankle will end up being:

m2 L22 [pic]2 + [m2 L1 L2 Cos ((2 - (1) ] [pic]1 + [m2 L1 L2 Sin ((2 - (1) ] [pic]22 + m2 g L2 Sin (2 = (2

(m1 + m2) L12 [pic]1 + [m2 L1 L2 Cos ((2 - (1)] [pic]2 – [m2 L1 L2 Sin ((2 - (1)] [pic]22 + (m1 + m2) g L1 Sin (1 = (1

4. EXPERIMENTAL ROOM LAYOUT / (TENTATIVE):

5. LABORATORY EQUIPMENT

The Pro-Form SR20 provides EKG™ grip pulse sensors to help you monitor your heart rate, while the Competitor™ control panel displays your speed, time, distance and calories/fat calories burned. With this machine the student will be able to acquire some of the basic data needed to calculate kinematics equations. Refer to the procedures section to know what to record from this machine.

The Tanita Body Fat Scale TBF 679, provides a user memory, and body fat increments of 0.5%. The weight capacity of the Tanita is of 300 lb (136 kg), and provides an increment of 0.2 lb (0.1 kg). Students are required to measure & record their weight before performing the exercise experiment. Each experiment will vary according to each member’s body weight.

Starrett D3416 Digitape 3/4" x 16' Electronic Tape Measure. It comes equipped with an inches or mm button for instant conversions and also a zero button sets zero reading at any blade position. Students are required to measure & record lengths from the hip joint to the knee joint and onto the ankle joint. Height measures might be helpful during calculations.

The CCD Camera features 410,000 / 270,000 Pixels, which is much more sensitive then many on the current market. There is also Variable gamma controls and includes an easy to use on-screen menu and adjustments. The output is variable up to 75 hertz, 75 frames per second. Camera will capture movements of reflective markers at the hip, knee, and ankle joints.

The data acquisition software, OrthoTrak, is from . OrthoTrak is a fully automated, three-dimensional, clinical gait measurement, evaluation and database management system. The OrthoTrak System easily integrates cinematic and kinetic analysis with EMG and force

plate data. OrthoTrak allows the student to easily record the physical measurement data with the gait report, and quickly compile technical data into simple, easy to read, charts and graphs. Keep in mind that OrthoTrak is the only clinical package that allows critical upper body measurements (head, trunk, arms, and shoulder kinematics), which compliment lower body kinetics and kinematics.

In order to prevent damage to the floor from the bike there will be an Apache Mills Equipment Mat[pic]. The durable, easy to handle mat protects and reduces stress on the floors and carpets. It is 36 in. wide x 72 in. long x 1/4 in. thick, with a textured, slip resistant surface.

Sensotec manufactures the Pressure Sensors being used in the bike pedal. The Model 13 compression-only subminiature load cell is designed to measure load ranges from 50 grams to 250 lbs.  With subminiature dimensions these units are easily incorporated into systems having limited space. The load cell also features a mV/V output.

In order to read the data from the pressure sensor a signal conditioner is required. We are using a signal conditioner from Sensotec. It features a Panel digital Meter along with a full function signal conditioner. It also has an amplifier and power supply that works with non-amplified mV/V transducers.  It provides shunt calibration, which enables the system to be set up without using an expensive primary stimulus.

The Aspire Edge Knee Brace is the top of the line fully functional brace with features that usually cost more. Reflective markers will be placed on the brace rather than the student’s leg to obtain a more accurate signal reading from the CCD Camera.

These reflective markers are simply small pieces of plastic that are attached to the knee brace and used to collect the position data of the knee movement by the CCD Camera.

Camera Stand

The stand is necessary to make sure the CCD is placed at the proper height. A simple camera stand can easily be created and manufactured. Specifications for this piece of equipment are to be determined.

6. PROCEDURE

This laboratory experiment requires that each group member perform his or her own exercise and record his/her output as well as every group member’s output for comparison purposes. Each student will be required to warm up prior to performing exercise and to pedal for approximately 2 minutes. Recording of motion from CCD Camera and Pressure Transducer will start after steady motion has been reached. This would take approximately 30 seconds into the exercise. Enough belt resistance should be present to require students to apply some level of force on the pedal. Force applied to the pedal should be greater than the force provided only by the body weight. The procedures to perform this laboratory exercise is broken in two categories:

a. Motion Capture

Before you start the pedaling exercise the following must be measure:

a. Measure length of Femur, Tibia (L1, L2).

b. Record body weight.

c. Measure student’s height.

d. Place and adjust knee brace on right leg

After measuring the above:

e. Start pedaling until reaching a steady state pedaling motion.

f. Maintain a constant pedaling frequency. This in order to examine changes in joint kinematics parameters in knee and ankle.

g. Pedal for approximately 2 minutes at two different velocities.

b. Data Collection

h. With constant motion into the pedaling cycling start recording motion for little less than 1 minute. Increase or decrease velocity and record again for little less than 1 minute. Each group member should perform the exercise procedure.

i. From exercise bike console record velocities for both scenarios for each member of the group.

j. Save data provided by CCD camera and Pressure Transducer on 3.5 Floppy Disk. Students should have numeric data for Angles, Angular velocity, and Angular Acceleration with respect to time for hip, knee, and pedal angle variation or ankle.

7. REPORT

a. For each setting V1, and V2 provide graphs for angle variation during cycle, angular velocity, and angular acceleration with respect to time. Each graph should include curves for hip, knee, and pedal (ankle) angle variation. Do the same for one of your team members and compare results base on body weight, Femur, or tibia length. Provide discussion on differences and similarities.

b. For both settings show calculations of where maximum Torque on pedal occurs? At what point in the cycle is torque a maximum? What is the magnitude of this Torque applied at the crankshaft? Perform these calculations mathematically from the formulas derived. Do the same steps for one of your group members. Discuss differences and similarities. Compare results for torque with those obtained by the Pressure Transducer. Discuss potential for error and improvements.

Table 1. Anthropometric Parameters of the Human Body.

|SEGMENT LENGHTS |

|SEGMENT |MALES |FEMALES |

|Thigh |23.20 |24.90 |

|Lower Leg |24.70 |25.70 |

|Foot |4.25 |4.25 |

|Segment lengths expressed in percentages of total height. |

|SEGMENT WEIGHTS |

|SEGMENT |MALES |FEMALES |

|Thigh |10.50 |11.75 |

|Lower Leg |4.75 |5.35 |

|Foot |1.43 |1.33 |

|Segment weights expressed in percentages of total body weight. |

|SEGMENTAL CENTER OF GRAVITY LOCATIONS |

|SEGMENT |MALES |FEMALES |

|Thigh |43.3 |42.8 |

|Lower Leg |43.4 |41.9 |

|Foot |50 |50 |

|Segmental center of gravity locations expressed in percentages of segment lengths; measured from the proximal ends of segments. |

Table 2. Data sheet for Human Motion Evaluation

|Time |Velocity (SS) |Body Weight |Length |Length |

|(SS) | | |Hip - Knee |Knee - Ankle |

|Student 1 |V1 | | | | | |

| |V2 | | | | | |

|Student 2 |V1 | | | | | |

| |V2 | | | | | |

|Student 3 |V1 | | | | | |

| |V2 | | | | | |

|Student 4 |V1 | | | | | |

| |V2 | | | | | |

*** SS = Steady State

REFERENCES

• Susan J. Hall, “Basic Biomechanics,” Appendix D, Anthropometrics parameters for the human body.

• Christopher L. Vaughan, “Biomechanics of Sport,” Mechanics of Cycling, pp. 289-313.

• Meirovitch, Leonard “Fundamentals of Vibrations,” The McGraw-Hill Company inc. New York, NY 2001

Appendix C – CAD Drawings

Figure C1: Overhead view of the laboratory set up and layout.

Figure C2: Exercise bike with the camera positioned.

Figure C3: The view of the bike from the CCD camera.

Figure C4: Rider on the exercise bike.

Appendix D – Numerical Analysis, Data and Plots

Figure D1: Plot of Angle Data vs. Time

Figure D2: Plot of Angular Velocity vs. Time

Figure D3: Plot of Angular Acceleration

Data Tables

-----------------------

m1

(2

(1

m2

L1

L2

L4

X

(0,0)

L3

(X3,Y3)

L1

(1

X

m1

Drawing 1: Pendulum Diagram

(X3,Y3)

L3

(0,0)

L4

L2

m2

(2

(1

(2

L4

L2

L1

(3

L3

H = (4, 24)

K=(x2,y2)

(0,0)

Drawing 2: Reference frame

Drawing 3: Apparatus for Bicycle exercise and data collection.

PC

Bicycle Console

[pic]

Pressure Transducer

Exercise Bicycle

CCD Camera

[pic]

Figure 1: Exercise Bike

[pic]

Figure 2: Scale

Figure 3: Tape Measure

[pic]

Figure 4: CCD Camera

Figure 5: Data Acquisition Software

Figure 6: Floor Mat

Figure 7: Pressure

Transducer

Figure 8: Signal

Conditioner

Figure 9: Knee Brace

Figure 10: Reflective Markers

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