Modeling and Control of a Lizard-Inspired Single-Actuated Robot

In this study, trajectory-tracking control for a lizard-inspired single-actuated robot (LISA) is implemented using a novel morphology. A high degree of reproducibility is obtained between the results of kinematic analysis and the behavior of the actual robot. Several 1-degree-of-freedom (DOF)-driven robots have been proposed. However, the application of these robots is severely restricted because of their inherent morphology limitations. LISA is a multilegged robot that can overcome these disadvantages and propel and turn with 1-DOF. In this study, we formulate the kinematics, such as the turning angle and stride length, of LISA. Furthermore, a unique robot coordinate is defined to enable the symmetrical representation of critical robot state quantities. Next, a trajectory-tracking control system based on the proportional-integral-derivative (PID) control is designed, and it is verified by both experiments and numerical simulations. Finally, the results of the experiments and numerical simulations are quantitatively compared according to the root mean square, and the reproducibility of the kinematics analysis and the behavior of the actual system are discussed. This study makes the following contributions: (1) The morphology of LISA facilitates analytical results with only kinematic analysis, which is considerably simpler than dynamics analysis. (2) LISA achieved sufficiently good kinematic performance for the required motions. Experiments revealed that the designed trajectory-tracking control system allows for LISA to appropriately track several types of trajectories.