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TU-Live Webinar July 31, 2009

3D-MC2 Setup and Calibration

Questions and Answers:

Q. What does IMU stand for?

A: Inertial Measurement Unit

Q. Is the COR measurement inside (provided rotation is centered)?

A: COR, or Center Of Rotation, in the machine builder refers to the center of rotation of the blade TILT (slope) function (not to be confused with blade angle rotation). As shown in the presentation diagram, for 6 way blades it is the center of the dozer’s ball joint mount.  On 4 way blades or U frame blades, the center of blade tilt rotation is off toward the side of the blade opposite the tilt cylinder, and not necessarily identified by any physical mounting point.

Q: Is there a reason you couldn't use 1/2 of total blade width for the COR inside measurement on a six way blade?

A: It is very likely that it will indeed be ½ of the total blade width for a six way blade. However, since we don’t know manufacturing tolerances for welding the ball joint mount to the back of the dozer blade, the best practice would be to pull a tape measure.

Q: How do you know if your mainfall calibration is close enough for slopes?

A: Grade a pass in one direction, and then turn around and grade back over the previous pass. It should match grade. Remember that on steep slopes, you will need to operate slower than on flatter ground. Also, be sure to keep the blade rotated perpendicular to the direction of travel (square blade) as there is no compensation for blade rotation at this time.

Q: Do grousers affect outcome of the main fall calibration?  Is it better to calibrate on dirt or hard surface?

A: The key is to have the main fall match the slope the machine is working on. But since the main fall changes as the blade is raised and lowered, a machine with tall grousers would likely have a different mainfall reading on concrete than on dirt where the grousers were digging in. I would always recommend verifying the main fall calibration in the dirt. Grade a smooth planar surface, and then make a slow pass in manual mode with the cutting edge just brushing the ground. Note the main fall sensor reading while you are moving. It will be jumping around a bit, but you can get an average of what the main fall is reading in that direction. Then turn around and do the same in the opposite direction. The main fall reading should match; for example if you determine an average reading of 1.5% slope one direction, then you should determine an average reading of -1.5% in the opposite direction. If not, you can make small adjustments as needed.

Q: How critical is IMU behind? We have been measuring to the cutting edge, not the wing point.

A: Depending on how far the wing points are from the cutting edge you may experience grade errors when grading on steeper mainfalls.

Q. Are there any symptoms that indicate that we've taken bad measurements - i.e., that we're off?

A: Symptoms from incorrect machine builder measurements can be cutting incorrect grade and/or poor machine performance.

Q: What is the maximum main fall specification for 3D-MC2?

A: We do not have a published specification for the 3D-MC2 system regarding slopes, either main fall or side slopes. In my experience, on a 15% main fall it cuts correctly as long as I operated very slowly.

Q: If I understand correctly, you can only go fast if the machine is grading flat?  How flat?

A: We do not have any operational specifications for 3D-MC2. However in my personal experience, I have found that when grading on typical slopes speed isn't a problem. I had no problems operating fast on main slopes in excess of 8%, and side slopes of 33%. I did have to go slow with a main slope of 15%, and also when on a 50% side slope.

Q: Rarely can you grade without rotating the blade.  How much error is going to be introduced if you wind row to one side or the other?  

A: It is the same with our standard single antenna 3D-MC system; the amount of error depends on the mainfall, cross slope, rotation angle. Getting this issue solved is a very high priority for us. Our engineers are working hard to get a solution.

Q: At what slope is the compass inactive?

A: At this time the compass is not functional. It will be incorporated in a later code revision.

Q: What's the maximum slope for the compass function?

A: At this time the compass is not functional. It will be incorporated in a later code revision. Once released, the operating specifications will be available.

Q: What makes some machines "jumpy"?

A: Since the GPS signal has some “flutter”, it is also normal to have a small amount of “flutter” even with standard 3D-MC. With the more aggressive hydraulic and electronic control performance of 3D-MC2, it is normal to appear a bit more “nervous” than a standard 3D-MC system. As for differences from one machine to another, there are two primary factors involved; 1) The hydraulic performance of the dozer itself and the specific hydraulic interface we are using for that make/model (add a valve, direct electronic control, CAN interface, etc.) 2) The valve offset and gain functions.

As indicated in the webinar, if the valve offsets and gains are set correctly for 3D-MC2, it is normal for the blade to appear a little "nervous" or jumpy when the machine is stopped and in automatic control. The key is to adjust gains so that it cuts good grade in the dirt.

Q: How you identify the failures in the system? Does the software show someone code? Have specific solutions to each fail? And finally, is it easy to fix the failure if the operating system shows it?

A: The system does not display any error codes. If the 3D-MC2 sensor fails you will see an “off line” message on the slope indicator display. The error may be either the sensor, or the cable to the sensor. Having backup parts on hand to swap out makes field support easier and gets your customer up and running quicker.

Q: How do you troubleshoot 3D-MC2?

A. Overall, it is the same as for standard 3D-MC. For problems related to not matching grade, you will need to verify the sensor measurements and calibrations carefully, as well as the normal GPS antenna measurements.

Q: I've worked with a lot of sensors - there are inevitably failures....  How are we doing in that area?  How do we know?

A: The 3D-MC2 system and sensor has proven to be one of the most reliable we have seen upon release. It has been almost bullet proof!

Q: Has a temp range been determined for the GX-60 and the IMU?

A: The temperature specification of the MC2 sensor, GX-60, and MC-R3 is -20oC to +60oC. I do know that we had several beta systems operating in very hot conditions with no problems. You can contact the support department to get Technical Data Sheets on the components which include the operating specifications.

GX-60 TDS; P/N 7011-0140

MC-R3 TDS; P/N 7011-0157

MC2 TDS; P/N 7011-0165

Q: Is there an ETA for the later code revision?

A: The next code revision is scheduled for late fall. However, we don't know the extent of what new features will be included. The primary functions for the new code release will be to include grader, excavator, and standard 3D-MC with the new operating code.

Q: When is the new manual going to be released?

A: Later this fall.

Q: Is the Topcon University Website already active? I just tried it and came up with a '...not found' message

A: The TU Website is not yet active, however we have a TU FTP site where we are placing the webinar recordings and other training information which is currently active and will be until we get the TU Website going. You will find a direct link to the TU ftp site when you receive the next webinar invitation. Or, email Training@ and we can reply with the address.

Q: I entered a little late, what did I miss?

A: You can download a recording of all TU-Live webinars from the TU FTP site. The Friday webinars will be available on the site the Monday following the webinar.

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