Motion control of cooperative transportation system by quadruped robots based on vibration model in walking

We propose a cooperative transportation method by quadruped robots with vibration in a 3-dimensional environment. In the case of cooperative transportation by legged robots, we must solve two problems; (1) how to avoid exerting excessive internal force on an object and how to deal with sensed values, the position and orientation of the object with vibration because the body of the robot vibrates in walking; and (2) how to decide its velocity that depends on several parameters such as step, walking cycle, and so on. Considering these problems, we construct the cooperation method of the transporting system with vibration. Our method consists of three aspects; firstly we decide how to suitably distribute the object's degree of freedom (DOF) to two quadruped robots. Secondly how to decide the robot velocity is described. Thirdly we create the vibration model aimed at the periodic gait of a quadruped robot by filtering the ingredient of the robot vibration from sensed values of the object deviation from its normal position on the robot. The created model enables us to estimate the deviation of object on the robot and the vibration parameters of the other robot. Moreover, we propose the step prevention motion of quadruped robot where its velocity is close to zero. The effectiveness of the step prevention motion and gait based on the vibration model is verified by some experiments.