Thursday, 26 December 2013

Elbow Mod Update

Since the last update I have fixed numerous bugs the navigation errors where due to a damaged encored disc and the arm jitter was due to mismatched names in the Joint state publisher. one of the requirement for ROS MoveIt is a follow joint action server this now works I was ready to start using MoveIt then the elbow worm broke again, the printer not working at this time so I incorporated the elbow mod into the robot.The original idea was to use a MXL belt but the weight and acceleration  cause the belt to slip, after a change to #25 chain and sprocket to operation was better. One side affect of this mod is the arm can droop down which on power on causes a sudden jerk as the arm moves to start position. A simple adjustment to the start position and to place the arm into the tuck position for driving will be required, maybe a spring to hold the weight   will also help.

Tuesday, 3 December 2013

Inmoov arm and ROS MoveIT

This is the start of my efforts to run the Inmoov arm with ROS MoveIT. I have had to make some changes to the inmoov arm. ROS requires feed back and the servos used don't have feed back I tried to attach a wire from the Potentiometer to the adruino but this proved unstable and the servos were weak I replaced the servos with gear motors and a controller board all position readings and angle requests are done via I2C thru a master arduino.

First task is a URDF model  I'm only using 1 arm with only 4 joint to start
launch the model in RVIZ and make sure the model moves as expected the adjust the real robot to match the model (or simulation wont work as expected)

 next task run moveit setup assistant
 " roslaunch moveit_setup_assistant setup_assistant.launch"
I had to run this on the robot not a remote session.  I follow the  tutorial just using the default settings. After saving the configuration file (don’t forget to add the directory to the package path) it's time to test in simulation.

I the launch files generated there is a demo mode launch that and maximize the rviz window. I the motion planning tab go to planning set a start position and a end position(random) then run the arm will move to the new position   cool!

add some obstacles to the scene and see how the arm reacts

to be continued