It's important to note that the arm has 4 collinear joints and the sum of these positions gives the wrist extension distance. The wrist extension is needed when sending [joint trajectory commands](follow_joint_trajectory.md) to the robot. Here is an image of the arm joints for reference:
It's important to note that the arm has 4 prismatic joints and the sum of these positions gives the wrist extension distance. The wrist extension is needed when sending [joint trajectory commands](follow_joint_trajectory.md) to the robot. Here is an image of the arm joints for reference: