Velocity and Acceleration Estimation by a Nonlinear Filter Based on Sliding Mode and Application to Control System

Proportional-integral-derivative (PID) control commonly used to operate mechanical systems has limited performance accuracy due to the influence of gravity, friction, and joint interaction caused by modeling error. Digital acceleration control is robust against modeling errors and superior to PID control, but the need for positioning, velocity, and acceleration knowledge constrains the development of digital acceleration control. To overcome this limitation, this report introduces the system which estimates the smoothed and differential values using sliding mode system (ESDS). Using ESDS enables digital acceleration control without increasing the number of sensors over that used in PID control. This paper focuses on the influence of gravity because digital acceleration control can, in principle, cancel its influence. This controls mechanical systems appropriately under attitude variations. Results of proposed control are demonstrated using 1-and 2-link manipulators.