A simplified time-delayed disturbance observer for position control of robot manipulators

Disturbance observers (DOB) are used to reject external disturbances as well as inherent internal uncertainties. The time-delayed control method is also a kind of DOB that cancels out uncertainties by delayed information. Relying on a delayed control input may cause the phase delay in the system, and it further leads to the instability of the system. Another problem is to use an acceleration feedback which is so noisy that the performance may be degraded. In this paper, a simplified time-delayed DOB(STD DOB) is introduced to compensate for the weakness of using the acceleration information. To confirm the feasibility of STD DOB, simulation and experimental studies of position control of the two link robot manipulator is performed and evaluated.