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可重构轮手一体机器人群体构形动力学建模及运动规划研究
其他题名Dynamics Modeling and Motion Planning of the Group Configurations of Reconfigurable Wheel-Manipulator Robots
胡亚南1,2
导师马书根 ; 王越超
分类号TP242
关键词可重构机器人 轮手一体机器人 动力学 运动性能 运动规划
索取号TP242/H53/2016
页数118页
学位专业机械电子工程
学位名称博士
2016-05-25
学位授予单位中国科学院沈阳自动化研究所
学位授予地点沈阳
作者部门机器人学研究室
摘要可重构机器人对不同环境的适应性归功于其能够根据环境信息和自身的运动特性选择合适的构形以及相应的运动方式。然而可重构机器人丰富多样的构形、模块间复杂的耦合关系以及机器人与环境间复杂的交互作用为其控制和运动规划带来了困难。作为机器人运动特性的数学描述,动力学模型联系着机器人与环境的交互作用,其影响贯穿了构形的选择、构形的变换和构形的运动等各方面。因此本文以动力学为基础对可重构机器人的运动规划展开深入的研究,主要包括如下几方面的内容:1.轮手一体机器人群体构形的通用动力学建模作为一种可重构机器人,轮手一体机器人潜在的群体构形形式多样,而且不同构形与环境的接触约束也不同,单独针对特定环境中的特定构形建立动力学模型不仅耗费时间和存储空间,从控制的角度也不利于控制器设计和运动规划。所以提出一种通用的动力学模型对其进行统一描述。通过在结构形态、运动特点和约束及接触方式等方面进行类比,借鉴多指灵巧手中的抓持建模方法,建立了轮手一体机器人群体构形的通用动力学模型。借鉴微分几何中局部坐标的思想,采用李代数坐标对单模块的构型进行局部描述,得到动力学模型不含奇异点。采用定义在速度空间的广义关节模型对约束和接触进行描述,使模型兼容任意的时变约束类型。通过群体构形实例对模型的生成过程进行说明,并通过数值仿真对比对模型的正确性和通用性进行了验证。2.轮手一体机器人群体构形的运动性能分析轮手一体机器人在复杂环境中运动时将面临多种地形和地面特性,论文基于动力学模型对轮手一体机器人的典型群体构形在斜坡、台阶和沟壑地形中的运动性能进行分析,并为运动规划中的构形选择提供依据。在斜坡爬行性能分析中,首先提出了轮手一体机器人履带的简化受力模型,并基于静力学模型将极限爬坡能力的问题转化为非线性优化问题,进而得到了构形在不同摩擦系数下的最大爬坡角度;在台阶越障性能分析中,对影响单模块越障过程的运动参数进行了分析讨论。由于越障时机器人的重心升高造成容易倾翻,对越障时的稳定性进行分析并得到机器人的稳定越障参数范围。通过对典型群体构形越障过程的动力学仿真得到其能够越障的环境参数。基于抓持约束方程提出并分析了新的越障构形,通过对其越障过程进行逆动力学计算,得到了机器人手臂关节的控制量。在沟壑通过性能分析中,将运动分为爬行通过和翻转通过,并从几何和受力角度计算得到每种运动方式下能通过的沟壑参数范围。3.轮手一体机器人群体构形的运动规划方法研究可重构机器人的运动规划既需要考虑环境的机器人运动的影响,还要考虑构形变形带来的影响。为实现这一目标,提出融合轮手一体机器人构形变换的运动规划方法。使用具有层次结构的动态图对机器人群体的构形和不同构形间的转换进行表示。用图层表示机器人离散的构形空间,将机器人的运动分解为状态空间中的移动和构形空间中的变换,并使构形的选择与运动轨迹生成解耦,降低搜索空间的规模。根据机器人的分解运动类型,将运动规划分为移动规划和重构规划,避免同时处理带来的复杂约束。针对移动规划,提出将反馈运动规划与采样法相结合的启发式采样法,提高了搜索效率和生成解的质量。针对重构规划,通过对鲁棒控制下的机器人动力学的稳定性进行分析,提出基于简化模型的能量次优重构规划方法。通过仿真实例对运动规划方法的有效性进行验证,结果证明提出的方法能够根据环境特征和机器人群体构形的运动性能选择最优的群体构形并生成满足动力学约束的次优运动轨迹。
其他摘要The adaptability of reconfigurable robots to different environments is due to the fact that they can choose the suitable configuration and the corresponding type of motion based on environmental information and their own motion characteristics. However, because of the variety of the configurations, the complex coupling relations between modules and the complicated interactions between the robots and the environments, the control and motion planning of reconfigurable robots are difficult. As a mathematical description of the motion characteristics of a robot, the dynamics relates the interactions between the robot and the environment, which influence the choice of configuration, the transformation of configurations and the motion of configuration. Therefore, this thesis performs a thorough study on the motion planning method of the reconfigurable robots based on the dynamics of the robots. Aiming at the problems in the dynamics and motion planning of the reconfigurable robots, the following studies are performed. Firstly, the dynamic model of the group configurations of the wheel-manipulator robots is established. The wheel-manipulator robot, as a reconfigurable robot, can form many different types of group configurations, in which the constraints are different. It needs more effort and storage space to establish each specfic group configuration in the specfic environment. Therefore, we propose a general dynamic model to describe these factors in a unified way. By drawing the analogy in terms of the structural morphology, motion characteristics and the contact constraints, the general dynamic model of the group configuration of the wheel-manipulator robot is established by using the techniques from the modeling of grasping of multifingered hand. Based on the idea of local coordinates from differential geometry, the configuration of a module is described by the Lie algebra coordinates locally, which makes the dynamic model free from singularities. By using the general joint model defined on the velocity space to describe the contact and constraints, the dynamic model can be used to handle various time-varying constraints. The generation of the dynamic model is demonstrated by an example, and the validity and generality are verified by numerical simulations. Secondly, the motion of the group configurations of the wheel-manipulator robots is analyzed. Many terrain shapes and features may be encountered when the robots are moving in the complex environments. This thesis analyzes the motion capabilities of the typical group configurations of this robot in the slope, step and trench environments, which provides a basis for the configuration determination in the motion planning. In the slope-climbing analysis, the simplified force model of the track is proposed. The problem of limit climbing ability is transformed into an nonlinear optimization problem. The maximum angle of the slope that the robot can climb in different friction coefficient are then derived. In the analysis of step-obstacle negotiation, the motion parameters that influence the obstacle negotiation process of a single module are analyzed and discussed. Because the gravity center of the robot increases when negotiating a step-obstacle, the robot may lose stability and tip over. Thus, the stability is analyzed, and the range of obstacle parameters that the robot can negotiate is obtained. The parameters that the typical group configurations can negotiate are obtained by dynamical simulations. Based on the grasp constraint equations, new group configurations that are more capable of negotiating obstacles are proposed, and the inverse dynamics is performed to derive the control signals of the arms’ joints. In the analysis of trench-crossing, the motion of the robot is classified into cross by climbing and cross by rotating. The parameters range that each type can cross are obtained from the aspects of geometry and force conditions. Thirdly, the motion planning for the group configurations of the wheel-manipulator robot is studied. The motion planning of reconfigurable robots not only has to take the influence of environment to motion into consideration, but also the influence of the transformation of configurations. To achieve this, a motion planning method incorporating the configuration transformation of wheel-manipulator robots is proposed. By using the dynamic graph with layered structure to describe the group configurations and their transformations, the discrete configuration space is expressed in layers, and the motions of the robots are separated into locomotion in the state space and transformation in the configuration space. The choice of configurations and the generation of trajectories are decoupled to reduce the size of the compound search space. The motion planning is further separated into locomotion planning and reconfiguration planning based on the motion types of the robot, which can avoid to handle the complex constraints when planning at the same time. In locomotion planning, a heuristic method combining the feedback motion planning method and the sampling-based method is proposed that can promote efficiency and increase the quality of the trajectory. In reconfiguration planning, an energy suboptimal reconfiguration method is proposed based on the analysis of the stability of the dynamics of the robot under robust control. The effectiveness of the motion planning method is demonstrated by an example. The result shows that the proposed method can choose the optimal configuration for each terrain, and the obtained energy-suboptimal trajectories satisfy the dynamics of the robots.
语种中文
产权排序1
文献类型学位论文
条目标识符http://ir.sia.cn/handle/173321/19678
专题机器人学研究室
作者单位1.中国科学院沈阳自动化研究所
2.中国科学院大学
推荐引用方式
GB/T 7714
胡亚南. 可重构轮手一体机器人群体构形动力学建模及运动规划研究[D]. 沈阳. 中国科学院沈阳自动化研究所,2016.
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