摘要
双腿轮式机器人融合了足式与轮式机器人的优势,展现出灵活性和高速高效特性。然而,精确控制这类机器人需要对运动学和动力学模型进行深入研究。此外,欠驱动、强耦合和非线性等控制难点也进一步加剧了机器人运动与自平衡控制的挑战。为应对这一挑战,本文提出一种分布式动力学建模策略,分别对机器人的躯干及腿轮子系统进行了精确建模,保留了机器人的所有动力学特性,并据此设计出以腿轮末端输出力矩为控制目标的力矩解算器。随后,基于该模型创新性地提出一种全身力矩控制框架,旨在实现双腿轮式机器人的运动控制和动态平衡。为进一步提升其运动性能,还规划了多运动模式,并成功地集成到全身力矩控制系统中。在MATLAB环境下搭建了双腿轮式机器人仿真实验平台,设计了两种行走实验方案和3种不同跳跃高度的仿真实验。实验结果表明,行走速度误差小于0.09 m/s,跳跃高度误差控制在0.02 m以内,验证了控制策略的可行性。最后,搭建了腿轮融接型复合结构的双腿轮式机器人,成功开展了机器人多运动模式实验,进一步证实了机器人在运动控制作业中的高精度表现,其躯干高度误差在3.38 mm以内,俯仰角误差不超过0.04 rad。研究结果充分验证了分布式全身动力学建模的精确性以及全身力矩控制系统的有效性,为双腿轮式机器人的运动控制研究提供了新的理论框架和实践指导。
Objective The two-legged wheeled robot is a new type of composite ground mobile robot constituted by designing wheels at the end of the legs of footed robots,which combines the improved maneuverability and flexibility of traditional wheeled mobile platforms and footed robotic structures and has enhanced application scenarios and research value.However,the motion control of the two-legged wheeled robot is highly dependent on an accurate dynamics model.At the same time,it has control difficulties such as underdrive,strong coupling,and nonlinearity.These challenges lead to difficulties in achieving effective motion control and self-balancing of the robot.Therefore,proposing an efficient method for the motion control of a two-legged wheeled robot is of great practical significance.Methods This study adopts the idea of a distributed model to establish the dynamics model of the leg-wheel and torso subsystems and address the issue with the huge structure of the overall dynamics model of the two-legged wheeled robot,which is not conducive to characterization and the construction of the controller.These models retain all the dynamics characteristics of the robot and connect them to the inter-module motion/force transfer relationship to complete the whole-body dynamics with the wheel-leg-torso interaction force as the end output force model.Thereafter,the joint moment solver,with the end output force as the task space,is constructed based on this model.It includes feed-forward compensation of the rod inertia force caused by the initial state quantity performed by the observation signal.Then,a distributed control framework with torso position as the task space is proposed to plan the torso joint force and joint moment hierarchically,and the walking motion control architecture based on the whole-body moment is constructed.Based on this walking motion control architecture,an adaptive planning method for the longitudinal trajectory of the torso in jumping motion is proposed,giving the torso the longitudinal velocity required for jumping by planning the longitudinal motion of the torso.To ensure the smoothness of the velocity and acceleration of the jumping motion trajectory,a cubic polynomial is utilized to plan the torso height trajectory of the jumping support phase,the torso height trajectory of the jumping airborne phase is obtained by integrating the velocities,and the variation of its torso height trajectory is presented.Furthermore,the control method of the airborne phase based on the virtual model and the momentum moment theorem is proposed when the torso reaches the jumping speed by controlling the contraction of the legs to detach from the contact between the wheel and the ground and enter into the free-fall state,and the whole jumping process is presented.Finally,the effectiveness of the whole-body moment control system is proved through simulation experiments as well as prototype tests.Results and Discussions A simulation experiment platform is developed using MATLAB to demonstrate the feasibility of the distributed dynamics modeling and whole-body moment control framework for the two-legged wheeled robot.Two walking experiment scenarios,including straightline and circular motions,are established,along with three jumping simulation experiments at different heights.The velocity following the curve for straight-line motion is shown,with a maximum error of no more than 0.09 m/s.The pitch angle and height following curves of the robot are displayed,indicating height errors ranging from−0.011 m to 0.002 m and pitch angle errors from−0.001 rad to 0.006 rad.For circular motion,the velocity following the curve is displayed with a maximum error of 0.071 m/s.The pitch angle and height following curves for circular motion indicate a maximum height error of 8.633 mm and a maximum pitch angle error of 0.006 rad.The jumping heights are 0.55 m,0.50 m,and 0.45 m,where the jumping results show a maximum jumping height error of no more than 0.02 m,confirming the feasibility of the distributed dynamics modeling and whole-body moment control framework proposed in this study.A prototype of the two-legged wheeled robot is developed,and multiple motion mode experiments are conducted.The pitch angle and height following curves for the prototype indicate a trunk height error of no more than 3.38 mm and a pitch angle error of no more than 0.04 rad.Finally,by comparing and analyzing the simulation experiment results and prototype experiments,it is found that coordinated wheel and leg movements can achieve higher motion following accuracy while maintaining dynamic balance based on the trunk as the task space.This confirms the correctness of the distributed dynamics modeling and whole-body moment control framework proposed in this study,providing an effective reference for the study of motion control of two-legged wheeled robots.Conclusions This study proposes a distributed whole-body dynamics modeling method to establish the dynamics models of the torso subsystem and the leg-wheel subsystem and realize the complete mapping of the robot's individual joint moments to the end output force to preserve the dynamic characteristics of the two-legged wheeled robot.A whole-body moment control framework is proposed based on the distributed whole-body dynamics model to achieve motion control and dynamic balance targeting the two-legged wheeled robot with the characteristics of instability,strong coupling,and nonlinearity.A multi-motion mode planning method is proposed based on the whole-body moment control framework to improve the motion performance of the two-legged wheeled robot.Finally,a simulation experiment platform is built to carry out the simulation experiments of jumping and walking motion modes to verify the feasibility of the whole-body moment control system based on the distributed dynamics model.A prototype of a two-legged wheeled robot based on synchronous belt-driven tandem legs and a carbon fiber plate frame is developed and tested in multiple motion modes to prove the correctness of the distributed dynamics model and the whole-body moment control framework of the two-legged wheeled robot.
作者
余坼操
马心知
朱学军
杨旭东
赖惠鸽
杨爱迪
YU Checao;MA Xinzhi;ZHU Xuejun;YANG Xudong;LAI Huige;YANG Aidi(School of Mechanical Eng.,Ningxia Univ.,Yinchuan 750021,China;Anhui Feidi Aviation Technol.Co.,Ltd.,Hefei 230026,China)
出处
《工程科学与技术》
EI
CAS
CSCD
北大核心
2024年第5期156-167,共12页
Advanced Engineering Sciences
基金
国家自然科学基金项目(51765056)
宁夏大学研究生创新项目(CXXM202418)。
关键词
双腿轮式机器人
分布式模型
力矩控制
运动控制
two-legged wheeled robot
distributed modelling
torque control
motion control
作者简介
余坼操(2001-),男,硕士生.研究方向:机电系统智能控制.E-mail:2311482756@qq.com;通信作者:朱学军,教授,E-mail:zhxj@nxu.edu.cn。
