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ptownrobotics

Junior Member
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Posts: 5
Reply with quote  #1 
We're having a problem with our programming. When we set our gear shift to the highest speed, the motors turn at different speeds rather then at the same speed, causing the robot to drift. The same thing happens in simulation as well. The display boxes in the first screenshot, my testing build, show that the input values are the same going into the motor block, the only difference being one is negative and another is positive. Yet something is happening with the motor block, causing them to turn at different speeds. The second screenshot is the XY Graph output from the simulation.

 Thank you very much for any help you can give.
   ~ Penelope Robotics

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png scrnshot1.png (70.32 KB, 5 views)
png scrnshot2.png (17.38 KB, 5 views)

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ptownrobotics

Junior Member
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Posts: 5
Reply with quote  #2 
Please close this question, we found out because motors have a max speed of -128 and +127, they were maxing out because of the gain 60 block. 
  Thank you.
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jgraber

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Posts: 156
Reply with quote  #3 
The motor power programming has a max value of +/-127, which has some effect on the actual rotation speed of the motor, but there are many other elements of the system that also contribute to the actual speed;  torque load, CW cs CCW rotation efficiency, MC29 power FET resistance, PTC resistance, etc.
Since you have no closed loop feedback on the actual rotation speed of each motor, it is typical that they don't rotate at the same speed, even given the same input value.
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