Moment of inertia and turning performance

[FrankJ]

The extreme case is "help my robot will not turn" or once you go mechanum you never go back

In the real world: watch the skid steers on a construction site & how they chew up the ground.

[icyplanetnhc]

Originally Posted by Al Skierkiewicz

Haochuan,
The "jumpiness" that teams describe is primarily the torque of your drive train overcoming friction with the floor. As a wheel breaks loose and the RPM jumps up, the result is a mini-wheelie when the tires again grab the carpet. In most cases with high friction tires (four or more wheels) this is the case when turning.

We hypothesized that the jumpiness of our turning is caused by the inherent rocking of the standard West Coast 6WD drivetrains. This rocking causes inconsistent resisting torque to the turning. Each time the robot rocks during a turn, the front or rear wheels would grab the carpet, creating an abrupt but sharp resisting torque to our turning before the robot begins rocking the other way. Each rock seems to amplify the jumpiness and bounce.

However, we noted that some teams are able to create very smooth 6WD drivetrains that are similar in configuration to ours (254's Slipstream, for example). We will analyze some high-speed footage to get a better understanding of why we are suffering from this problem.

[Al Skierkiewicz]

Robots have been doing this for more than the 17 years I have been here and drop wheel drive trains have not been around that long. When you have a lot of torque and friction something has to give somewhere.

[JesseK]

Do a CD search for "Trapezoidal Speed Profile". Also do a CD search for 254's 2011 code, as that was posted as well. They've refined their code to optimize a couple of things. There may also be a difference in turning response with brake versus coast mode on the Jags/Vics.