Thursday, 27 December 2012

Arm Control

Now that we have arm that works it time to start controlling it at first i will only controlling the arm not the hand ( I don’t have enough servo pins in in the adruino and have to wait until  i get a mega). We have a hacked driver that controls the arm joints by publishing a topic to the joint i.e.
rostopic pub -1 /Right_lift_joint/command std_msgs/Float64 -- 0.5
which moves the right shoulder lift joint to 0.5 radians. Radian are a pain to visualize so we have a model in RVIZ so we can see what is happening.
Joining the stl's in freecad only works in windows when I have more time i will add the other arm and add all the parts i think it looks good with the arm transparent seeing all the parts. The driver lacks real feedback  (hobby servos don’t have feedback) this will require another hack, the upside at the moment is feedback is the last commanded position this makes for a simple simulator. I have hacked a action server and i can send a sequence of poses the action server will run 1 pose until its complete (when feedback uses the actual position not the last commanded position) then move to the next.
The printed parts have held up  well with only a few breakages the main problem is PLA is too brittle now that i have the hang off printing ABS I will remake  the parts (the junk box of broken and obsolete parts is growing).
Next  milestone is a video

1 comment:

  1. Hi Peter,
    I posted the shoulder if you finally have too much breakage using rotparts for the shoulder.
    I can't wait to see a video!