闭链多足移动系统足地接触轮廓曲线设计方法

Foot-ground Contact Contour Curve Design Method of Close-chain Multi-legged Mobile System

提出一种闭链多足移动系统的足地接触轮廓曲线设计方法,用于补偿在行走过程中因闭链连杆机构的足端轨迹不可调整而导致的机身垂向位移波动,从而有效提高移动速度并提升驱动效率。首先,针对由曲柄驱动的闭链多足移动系统进行运动特性分析,获得机身垂向位移波动与最大有效步频之间的函数关系,确定机身垂向位移波动幅值为限制移动速度提升的关键因素。其次,采用矢量环路法建立并求解机械腿的运动学模型,基于反转法原理在小腿坐标系下构造与机身固定的虚拟地面,由运动周期内小腿位姿随曲柄相位的连续变化形成虚拟地面直线簇,求解包络线方程得到足地接触轮廓曲线。然后,根据轮廓曲线的补偿相位进行闭链多足移动系统的整机布置设计,并基于ADAMS软件进行垂向位移波动、行走速度和缓坡负重行走的动力学仿真分析。最后,设计制作原理样机并开展平地测速试验和缓坡负重行走试验,验证了应用所提足地接触轮廓曲线设计方法补偿机身垂向位移波动以提升行走速度和驱动效率的可行性。

A foot-ground contact contour curve design method of close-chain multi-legged mobile system is proposed,which is used to compensate the vertical displacement fluctuation caused by the unadjustable leg-end trajectories of the close-chain mechanical legs,and to increase the walking speed and driving efficiency.Firstly,the movement characteristics of the crank driven mobile system is analyzed,and the functional relationship between the maximal effective step frequency and the vertical displacement fluctuation of the body is revealed.The vertical movement fluctuation of the body is identified as a key limitation of the walking speed.Secondly,the mathematical model of the mechanical leg is established and the kinematics is analyzed by solving the vector loop equations.The virtual fixed ground is built in the body reference frame,and with the rotary of the crank,the ground lines cluster in the lower leg reference frame is obtained based on the reversal method.The foot-ground contact contour curve is obtained by solving the envelope formed by the ground line cluster.Thirdly,the quadruped unit and the multi-legged mobile system is designed.The virtual prototype of the mobile system is built in ADAMS,and the vertical displacement fluctuation,the maximal speed and the power consumption are measured from the simulation results.Lastly,an experimental prototype is fabricated and tested.The flat ground walking speed experiment and the slope ground loaded experiment verify the effectiveness of the proposed foot-ground contact contour curve design method to increase the walking speed and driving efficiency.