To understand the basic of planning a trajectory in joint-space and Cartesian-space, let’s consider a simple 2-DOF robot (mechanism). In this case, as shown in Figure 5.4, we desire to move the robot from point A to point B. The configuration of the robot at point A is shown, with a=20 องศา และ b=30องศา. Suppose it has been calculated that in order for the robot to be at point B, it must be a=40 องศา และ b=80องศา. Also suppose that both joints of the robot can move at the maximum rate of 10 degrees/sec. One way to move the robot from point A to B is to run both joints at their maximum angular velocities. This means that at the end of the second time interval, the lower link of the robot will have finished its motion, while the upper link continues for another three seconds, as shown in Figure 5.4. The trajectory of the end of the robot is also shown. As indicated, the path is irregular, and the distance traveled by the robot’s end are not uniform.