Monday 17 March 2014

Arm Encoders

Moveit is running nicely but the real arm and simulated arm have a different angle at first I thought it was just calibration  and the lack of rigidity in the system
it ends up it's all of the above and the potentiometers that i use for encoders. The potentiometers are linear types but they are not true linear there is a small variation in the angle to signal which can be up to +/- 6 degrees the start, end and middle being accurate. There is not much point in fussing with calibration with that much error. I have 2 choices magnetic encoders or a look up table for the angles, the encoder will be for a later date so for now I'll use a look up table. For the rigidity and smoothness of operation bearings are the only way to go. Using the fake robot in Rviz shows that a extra joint in the shoulder gives better performance  I  will try and add a shoulder pan joint to Robbie