Six-degree-of-freedom Control by Posture Control and Walking Directional Control for Six-legged Robot

We describe a six-degree-of-freedom control method for the posture (body height, and pitch and roll angles), body position (x, y), and yaw angle of a six-legged robot. First, we describe our posture control method using an impedance model while considering actuator dynamics, after which we describe a walking directional control method that utilizes the torque of rotating links and reaction forces of thigh and shank links as control inputs. For the posture control and walking directional control models, we built a Type-1 servo system and designed a linear-quadratic-integral control system that allowed the robot to follow the targeted body posture, body position (x, y), and yaw angle trajectories. Additionally, in response to an observed problem in which the feedback (FB) input for thigh and shank links generated by walking directional control interferes with the FB input for a thigh link generated by posture control, we will explain how the FB control input produced by posture control in our model generates a control input that eliminates the walking directional control interference. The effectiveness of our proposed control method is then examined through simulations using a three-dimensional model of the robot during straight walking and obstacle climbing behavior.