Baxter's arms and forward kinematics

Considering Baxter's arms up to the wrist cuff, each arm has seven values that define the rotation angle of each joint. Since the link lengths and joint angles are known, it is possible to calculate the position and orientation of the gripper attached to the wrist. This approach to calculating the pose of the gripper given the configuration of the arm is called forward kinematic analysis.

Fortunately, ROS has programs that allow calculation and publishing of the joint angles given a particular position and orientation of the gripper. The particular topic for Baxter is /robot/joint_states.

Joints and joint state publisher

Baxter has seven joints in each of its two arms and two more joints in its head. The topic /robot/joint_states publishes the current joint states of the head pan (side-to-side) joint and the 14 arm joints. These joint states show position, velocity, and effort values for each of these joints. Joint position values are in radians, velocity...