Numerical Simulations of a Novel Force Controller Serially Combining the Admittance and Impedance Controllers

This paper proposes a novel force controller that serially combines admittance and impedance controllers. The proposed controller is adaptable to an unknown changeable environment in terms of stiffness, and it is able to achieve high control accuracy and stable operation. First, conventional admittance and impedance controllers are recalled, and based on them, a new force controller is designed. Next, the proposed controller is applied to a one DoF system in contact with an external environment in the case where the contact stiffness is changeable, and compare the behavior of the proposed controller with that of the conventional simple admittance and impedance controllers through numerical simulations. Additionally, the proposed controller is applied to a two DoFs system including some nonlinearities, and proposes a design of the desired anisotropic admittance and impedance parameters to the proposed controller. This effectiveness is also demonstrated through numerical simulation results.