This paper stated a problem of dilemma among accuracy, robustness, and noisiness in an impedance control. Additionally, applying Three-degree-of-freedom (Three-DoF) control for the problem is proposed as a solution. By using Three-DoF control, the performance is improved in terms of the noisiness compared with a conventional framework. The effectiveness is verified by preliminary simulations and experiments. As a result, the proposed method improved the accuracy/robustness and noisiness simultaneously.

This paper proposes a Three-degree-of-freedom (Three-DoF) control that is extended from a Two-degree-of-freedom (Two-DoF) control. In a classical Two-DoF control, the command input response and the disturbance suppression characteristics can be determined independently. However, the disturbance suppression characteristic and the noise suppression characteristic have a trade-off relation. Thus, if the disturbance suppression property sets high, the noise suppression property becomes low, and vice versa. In Three-DoF control scheme, command input response, disturbance suppression, and noise suppression property can be determined independently. To realize above capability, the controlled plant is divided by utilizing its linearity and an additional controller is used. In this paper, the control system architecture and the controller design methodology are shown and its effectiveness are validated by position control simulations of a 1DoF DC motor model.

In this paper, a new method of center of mass trajectory planning using the zero-phase low pass filter is proposed. This method is based on a table-cart model which simply describes the relationship between center of mass and zero moment point. Generally, zero moment point should be controlled to realize dynamic motion. This method can easily generate the center of mass trajectory which realizes the desired zero moment point. In our study, this method is applied to wheel-legged locomotion. We will show the result that zero moment point can be sufficiently controlled even if quadruped wheel-legged mobile robot is approximated to a table-cart model. The effectiveness of the idea is validated by simulation and experiment.