Based on the Foot–Ground Contact Mechanics Model and Velocity Planning Buffer Control

Abstract

In order to reduce the impact of the leg joint motors and body electric devices of a falling robot, active flexible control based on force and velocity is proposed. A velocity planning buffer method based on a virtual model is proposed. We established a mechanical model of leg and ground contact. Then, we controlled the knee joint angular velocity change after the robot contacted the ground to reduce the collision impact force and to protect the robot’s joint motors and body’s internal parts. First, the relationship between contact force and velocity was analyzed through the contact mechanical model between leg and ground, and the target was determined. Then, by planning the velocity of the robot’s thigh and hip joint, the velocity mutation during contact was reduced so that the impact on the robot was reduced. This method can avoid complex accurate physics model building and complex torque signal interference filtering processing, the control process is simple and its effectiveness is verified by ADAMS simulation and experimental verification. The velocity planning buffer strategy was tested in experimental studies which showed that the contact force of the buffer strategy was 0.671 times that of no buffer. Additionally, the contact impact acceleration of velocity planning was 1.5505 g, which was less than the force 1.7 g of virtual model control. The velocity planning buffer strategy was better to protect the robot.