Designing H2/ H¥ Controller for Flexible Joint Robot to Remove Instabilities due to Saturation

Mixed H2/H∞ method is proposed to design a controller for flexible joint robots (FJR) considering actuator saturation. By considering the control action in the mixed sensitivity function one can reduce the amplitude of the control action but this may affect all frequencies. A more advanced method based on frequency weighting of the control action contribution in the mixed sensitivity function is considered here which may result in higher bandwidth. But this method is also limited and to get wider bandwidth the H2/H∞ method is proposed. This method is shown to be a very good remedy to remove instabilities caused by actuator saturation.