Landing Posture Adjustment and Buffer Performance Analysis of a Cat Robot

A method for the aerial posture adjustment of a cat robot is proposed by imitating the motion of falling cats. The falling process is phased into three periods: righting reflex, pitch attitude adjustment and landing buffer. The kinematic equations of posture adjustment phase and dynamic equations of landing buffer phase are built based on the theorem of moment of momentum and classical impact theory. The method of changing length and swing angle of legs is proposed to adjust the pitch attitude and the relationship between swing angle and pitch angle is got by calculation. The ground reaction forces, the vertical acceleration of the center of mass and the waist joint torque are calculated when the front and rear legs collide with the ground at different heights. The results show that the vertical acceleration of the center of mass and the torque of waist will reduce with the increase of the height difference. Therefore, the cat robot can obtain a suitable landing posture through legs swinging and improve the buffer performance.