The error is the difference between the desired and actual behavior of the manipulator. In any physical real-time control system, there is always a certain amount of error resulting from modeling error or different types of noise. One of the design parameters is the maximum allowable error. This depends on the nature of the tasks the manipulator is designed to accomplish. For example, in the medical field the amount of error allowed is much less than in a simple laboratory manipulator. The update frequency is the most dominant factor in minimizing the error. It is clear that increasing the update frequency results in decreasing the error. The update frequency, however, is limited by the speed of the machine used to run the system. Khosla performed some experiments to study the effect of changing the control sampling rate on the performance of the manipulator behavior [25] and showed that increasing the update rate decreases the error.