【作者】 王刚；

【导师】 张立勋；

【作者基本信息】 哈尔滨工程大学 ， 机械电子工程， 2011， 博士

【摘要】 针对仿蟹机器人复杂地貌行走时需要解决的步行足冲击力、机体稳定性差等技术问题,在机器人步行足轨迹规划、步态方法及柔顺控制等方面开展了理论与实验研究工作。提出了仿蟹机器人结构方案,包括：模块化关节、扁形弹性足尖结构、步行足以及躯体结构等。并从正运动学和逆运动学两方面对仿蟹机器人步行足以及机体的运动性能进行了分析和仿真。根据仿蟹机器人步行足关节角度的约束,利用搜索法求解步行足以及整机的可达工作空间。研究了仿蟹机器人步行足末端轨迹规划问题,采用三次样条曲线对仿蟹机器人步行足末端轨迹进行了规划。提出了自适应轨迹规划原理和轨迹库的基本建立方法与其调用机制。建立了虚拟样机系统的控制系统和仿真模型,对仿蟹机器人在复杂地形情况行走进行仿真分析,证明了仿蟹机器人较强的复杂地形适应能力。通过分析生物螃蟹的运动特点,对仿蟹机器人步行足的步序关系及步态参数进行了规划研究,提出了一种步态规划方法。依据静稳态条件,将机器人步行足依z字形分组,通过调节组内先后摆动的两步行足间的相位因子调整步序,并提出交错等相位波形步态。建立了步态参数方程,计算了步行足占空比,利用能耗比分析了相位因子与占空比变化对步态能量损耗的影响。步态仿真分析表明,随着占空比增大,能耗比值呈线性增加趋势,当占空比等于0.454,相位因子等于0.25时,躯体可以获得较高的移动速度和较好的运动稳定性,运动能量损耗最小。与双四足步态相比,机器人具有良好的行走稳定性和较低的能耗比。提出了仿蟹机器人的柔顺控制方法。分析了步行足与环境的接触模型,采用基于位置阻抗的柔顺控制方法,建立了机器人控制策略仿真模型。仿真结果表明采用柔顺控制的机器人在行走过程中的冲击力得到了抑制,步行足末端受力能够迅速稳定,无波动现象,说明该控制方法适用于机器人的行走控制。同时,由于处于摆动相与支撑相的步行足受到的外部环境干扰不同,特别是力信号的差异对控制的影响,将模糊控制器应用到步行足单关节的位置控制中,并进行了仿真分析与实验研究。结果表明模糊控制对力参数的变化具有较强的鲁棒性,适合作关节位置控制系统的控制器。研制仿蟹机器人实验样机,构建了测量实验平台,对仿蟹机器人复杂地形的运动性能进行了实验研究,为仿蟹机器人的深入研究奠定了基础。利用dSPACE实时仿真系统进行了仿蟹机器人步态实验,并对仿蟹机器人实验样机进行了平面运动和斜坡运动的测试。通过不同速度下的交错等相位波形步态与双四足步态的对比实验,验证了交错等相位波形步态的可行性,实验结果表明交错等相位波形步态在运动过程中,速度变化平稳,重心波动小,具有良好的运动稳定性。通过引入柔顺控制策略解决了仿蟹机器人行走时步行足冲击力的问题,消除了冲击力对步行足的影响。通过柔顺控制实验,对系统刚度变化进行了测试,实验结果表明,在该控制策略的作用下,机器人具有良好的柔顺性,在步行足受到冲击力时能够产生良好的缓冲作用。仿蟹机器人在行走过程中具有较高的运动稳定性,其冗余肢体结构使其能在复杂环境中仍保持稳定状态,即使个别关节出现故障仍然可以完成作业,具有较强的地形适应性。更多还原

【Abstract】 Theroy analysis and experimental study have been developed in this paper aiming at solving the leg impact and body stability problem during walking on the uneven terrains.The structure schemes of the crablike robot including modularization joints, elastic toe, walking legs and body structure are proposed. And the motion performance of the leg and body has been studied and simulated by forward kinematics and inverse kinematics. Based on joint angle constraints of walking leg, the reachable workspaces of the leg and body are worked out using searching method.The trajectory problem of the leg is studied and the tip trajectory is planned using cubic spline curve. An adaptive trajectory planning strategy and trajectroy database are put forward as well as the calling mechanism of database. The simulation which is made for testing the motion on the uneven terrain proves that the crablike robot has favorable environmental adaptability.The pace order and gait’s parameters of the crablike robot are planned based on the analysis of crab’s motion traits and a new gait planning method is put forward. According to the statistic stability, the walking legs have been distributed along Z-form and the alternating equal-phase wave gait is proposed after considering the effect of variable phase factor of the successive legs within a tetrapod group. The paper establishs the gait’s parameter function, calculates the duty factors of the legs and analyzes the changing effects of duty factor and phase factor using energy comsumption ratio. The results of gait’s simulation show that the energy comsumption ratio increases linearly with the duty factor. When the duty factor is 0.454, the phase factor is equal to 0.25 and the robot can walk with better moving stability and lower energy comsumption ratio than the double tetrapod one.The compliance control method of the crablike robot is proposed in this paper. Based on position impedance control method, the simulation model of control is established through analyzing the contact model between legs and environment. The simulation results indicate that the impact force is restrained during walking by using compliance control without leg fluctuation. That means the compliance control method is suitable for the walking control of the robot. Because the environment impacts on the transferring legs and supporting legs are different, especially the effect of different force signal, the fuzzy controlor is applied to the position control of a single joint and the simulation is carried out. The simulation results show that the fuzzy controler has strong robustness for the variation of force and is suitable for the controler of joint’s position control. And the compliance control of the robot is realized in the paper.The experimental platform for the crablike prototype is developed and the experiments of the motion performance on the complex terrain have been made sufficiently for the deep study. Gaits’experiments using real-time simulation system dSPACE and moving tests on flat groud and slope are carried out. Through the contrast experiments between alternating equal-phase wave gait and double tetrapod gait, the feasibility of the alternating equal-phase wave gait is proved. The results show that the velocity of alternating equal-phase wave gait changed smoothly with small fluction of gravity centre and the robot can receive favorable gait stability.The influence of the leg’s impact force is eliminated by using control strategy. Through compliance control experiment, the variation of system stiffness is tested. And the compliance control tests show that the robot can receive nice compliance performance and this method can provide a good buffer effect when the legs are subject to the impact force.The robot has high motion stability with stronge terrain adaptation. The crablike robot can also keep stable in complex environment because of its redundant structure and complete the operation even if some joints’are disabled.更多还原