Baxter's arms
Baxter has seven rotary joints, as shown in the following figure. Each arm is often referred to as a 7-DOF arm, since motion of the arm is controlled by seven actuators (motors), which are capable of independent rotation.
Baxter's 7-DOF arms are described on the Rethink Robotics site at http://sdk.rethinkrobotics.com/wiki/Arms.
The arm joints are named in the following manner:
S0: Shoulder Twist (Roll)
S1: Shoulder Bend (Pitch)
E0: Elbow Twist (Roll)
E1: Elbow Bend (Pitch)
W0: Wrist Twist (Roll)
W1: Wrist Bend (Pitch)
W2: Wrist Twist (Roll)
The designation of the joints as S0, S1, E0, E1, W0, W1, and W2 enables us to define, and even monitor, each of the angles for these joints with respect to the coordinates of the joints. In ROS, the angles are measured in radians. As there are 2π radians in a complete circle, one radian is 360/(2π), or about 57.3 degrees. A 90-degree angle is π/4, or about 0.7854 radians. These conversion values are given because it is often...