Joint Order and Direction

The action and observation structs contain arrays for joint positions, torques, etc. Each entry in these arrays corresponds to one joint of the robot.

Joint Order

On the finger robots, joints for each finger are ordered from the base towards the tip:

For TriFinger robots, the joints of the three fingers (“finger0”, “finger120” and “finger240”) are each ordered as shown above and then concatenated. That is, the joint array is ordered like this:

finger0_joint0, finger0_joint1, finger0_joint2, finger120_joint0, ..., finger240_joint2

See Names of Fingers and Cameras on how the three fingers are mounted for TriFingerPro.

Joint Directions

For “FingerPro” and “FingerEdu” fingers, directions of rotation (i.e. which direction is positive and which is negative) is as depicted in the image above. For “FingerOne”, joint 1 is inverted, the others are the same.

Zero Position

All joints are in zero-position when the finger is pointing straight down: