复杂地形下仿生轮腿式机器人位姿控制研究

Pose Control of Biomimetic Wheel-legged Robots in Complex Terrain

丘陵山地地势复杂、地形多变,农机装备作业环境以倾斜角度较大的斜坡为主,传统农机装备在丘陵山区复杂地形下作业时效率低、稳定性差,甚至会出现侧倾、翻车等现象。本文从仿生机械设计角度出发,提出一种在丘陵山地复杂地形下能够自主实现位姿调平控制的轮腿式机器人平台,提升复杂地形下的作业稳定性和安全性。以昆虫后足为仿生机械设计对象,并结合多连杆机构原理,完成新型变行程轮腿机构及机器人平台的整体架构设计。采用D-H参数法分析了轮腿机构运动学特性,结果显示轮腿式机器人离地间隙最大调整量为574mm,具备较强的越障能力。在空间坐标系上定义轮腿式机器人空间姿态参数,推导得到机身姿态角与轮腿伸缩量之间的空间姿态模型,并设计了基于NSGA-Ⅱ的机身空间姿态逆解算法。基于空间姿态逆解算法构建了轮腿式机器人全向位姿调平位姿控制系统,包含机身调平控制器、“虚腿”补偿控制器和质心高度控制器,在复杂地形下行驶时能够控制轮腿式机器人俯仰角、侧倾角、接地力、质心高度等空间姿态参数,然后通过搭建的轮腿式机器人ADAMS-Matlab联合仿真模型完成了位姿控制系统算法仿真验证。在机器人样机上开展了离地间隙自动调整和机身全向位姿调平试验,试验结果表明,试验样机离地间隙最大调整量为574mm,同时在复杂地形下能够实现机身位姿全向自动调平,调平平均时间约为1.2s,调平平均误差为0.8°,位姿控制响应速度与调平精度能够满足实际工作要求。

The terrain in hilly and mountainous areas is complex and diverse,and the operating environment of agricultural machinery equipment is mainly inclined slopes.Traditional agricultural machinery equipment has low efficiency and poor stability when operating in complex terrain in hilly and mountainous areas,and may even cause serious accidents such as tilting and overturning.A wheel-legged robot platform that can autonomously achieve pose leveling control in complex terrain of hills and mountains was proposed from the perspective of biomimetic mechanical design,improving the stability and safety of operations in complex terrain.Firstly,taking the insect hind foot as the biomimetic mechanical design object,and combining the principle of multi link mechanism,the overall architecture design of the new variable stroke wheel-legged mechanism and robot platform was completed.The kinematics characteristics of the wheel leg mechanism were analyzed by using the D-H parameter method.The results showed that the maximum adjustment of the ground clearance of the wheel-legged robot was 574mm,and it had a strong ability to surmount obstacles.Then the spatial attitude parameters of the wheel-legged robot were defined in the spatial coordinate system,and the spatial attitude model between the fuselage attitude angle and the wheel leg extension was derived.An NSGA-Ⅱbased algorithm for inverse solution of the fuselage spatial attitude was designed.Based on the spatial attitude inverse solution algorithm,an omnidirectional attitude control system for wheel-legged robots was constructed,which included a vehicle body leveling controller,a“virtual leg”compensation controller,and a centroid height controller.It can control the spatial attitude parameters of wheel-legged robots such as pitch angle,roll angle,grounding force,and centroid height when driving in complex terrain.The algorithm simulation verification of the pose control system was completed through the ADAMS-Matlab joint simulation model of the wheel-legged robot.Finally,experiments on automatic adjustment of ground clearance and omnidirectional posture adjustment of the vehicle body were conducted on the robot prototype.The results showed that the maximum adjustment amount of the ground clearance of the test prototype was 574mm,and the omnidirectional automatic leveling of the vehicle body posture could be achieved in complex terrain.The average leveling time was about 1.2s,and the average leveling error was 0.8°.The response speed and leveling accuracy of the posture control could meet the actual work requirements.