空间机器人动力学参数辨识及其软件设计

硕 士 研 究 生： 夏丹 导 师： 李瑰贤 教授 申 请 学 位： 工学硕士 学 科 、 专 业： 机械设计及理论 所 在 单 位： 机电工程学院 答 辩 日 期： 2009 年 6 月 29 日 授 予 学 位 单 位： 哈尔滨工业大学
Classified Index: TP24 U.D.C.: 510.80
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哈尔滨工业大学fied the result by least square method. At last, the paper also utilizes GUI in MATLAB to program software for the problem of identification for two-joint and six-joint space robots, fulfill the interface display of input-output of parameters identification, then expresses the identification effect in figures visually, enhanced the interaction of interface. Keywords space robots, dynamics parameter identification, least square method, genetic algorithm, software programming
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哈尔滨工业大学工学硕士学位论文
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Dissertation for the Master Degree in Engineering
DYNAMIC PARAMETERS IDENTIFICATION AND THE SOFTWARE DESIGN OF SPACE ROBOT
Candidate: Supervisor: Academic Degree Applied for: Specialty: Affiliation： Date of Oral Examination:
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哈尔滨工业大学工学硕士学位论文
Abstract
For a space robot there are some errors between its nominal dynamic parameters and real dynamic ones because of some factors of machining and assembly. However, path planning for the space robot is different from that on the ground, since the dynamic parameters exist in its generalized Jacobian matrix, the calculated trajectory will deviate from the really desired one, which will cause some pose errors of the end-effectors. In order to make space robots get higher Precision when space robots execute space task, the identification of dynamics parameter shows more important. However, because of the microgravity environment, some methods which use the principle of gravity balance fail to unitize. Furthermore, some sensors use to measure acceleration and driving moment in space robots have lower signal-to-noise ratio. How to study on the economic and feasible method for identification of dynamics parameters in the space task for space robots is the difficulty points in the area. At the same time, that is the research purpose of my paper. In the research, the system of space robots only need to assemble angular and base displacement sensor and angular velocity sensor, not to assemble base force/Torque Sensor and acceleration sensors, moreover, the paper use the method which base on the conservation of angular momentum, finish the identification process by the deviation value of flywheel angular momentum, simplified the space robot system, economized the cost. First of all, according to the conservation of angular momentum equation, it obtain the error model, according to cubic polynomial interpolation, it plan the Trajectory of base and angular., then identified the two – joint space robot model by least square method and genetic algorithm. Based on the theory, the paper research on the identification problem of sixjoint step by step. In least square method, the paper contrast the curve of flywheel angular momentum in the direction of roll, pitch and yaw, at the same time, the paper identifies the problem by genetic algorithm, in the process of identification, it appeared the early maturity phenomenon, induce the process of optimization terminated in advance, expected goals cannot be achieved, because of this reason, the paper improves the genetic algorithm by the method of small section method, elites to keep the tactics, big mutation operation. After the improvement of genetic algorithm, comparing the identification result from least square method, genetic algorithm appeared the superiority when parameter matrix is more complex. The paper also studies on the identification of unknown object captured by the space
硕士学位论文
空间机器人动力学参数辨识及其 软件设计
DYNAMIC PARAMETERS IDENTIFICATION AND THE SOFTWARE DESIGN OF SPACE ROBOT
夏丹
2009 年 6 月
国内图书分类号：TP24 国际图书分类号：510.80
工学硕士学位论文
空间机器人动力学参数辨识及其软件设计
哈尔滨工业大学工学硕士学位论文
摘
要
由于加工、装配误差以及在轨燃料消耗等原因，空间机器人名义动力学参 数与实际动力学参数相比存在一定的误差，而空间机器人路径规划和地面机器 人不同，其广义雅克比矩阵包含动力学参数，从而使计算轨迹偏离所要求的路 径，所以必须对动力学参数进行辨识，另一方面，为了提高控制精度，也需要 精确的动力学参数。因此，动力学参数辨识尤为重要。然而，在空间微重力环 境下，某些利用重力平衡原理的辨识方法无法应用；此外，用于测量空间机器 人关节加速度和驱动力矩的传感器，信噪比也较低。因而，在考虑空间机器人 的实际工作状态的情况下，研究一种经济、可行的动力学参数辨识方法，一直 是该领域的研究难点，同时也是本文研究的目的所在。 本文采用基于角动量守恒的动力学参数辨识方法，通过测量安装在基座上 的反作用力飞轮的角动量，并与利用系统名义动力学参数所计算的飞轮角动量 相比较来完成辨识过程。依据此种方法，空间机器人系统仅需安装常规的关节 角位移和角速度传感器、基座角位移和角速度传感器，而无需增加额外的传感 器，因而，简化了空间机器人系统，节约了研制成本。 首先，本文根据角动量守恒方程式建立动力学参数辨识的误差模型。以此 为基础，利用三次多项式插值法规划基座以及各关节的轨迹，实现对空间机器 人系统的激励。根据激励的结果，分别用最小二乘法和遗传算法对两关节空间 机器人模型进行动力学参数辨识仿真。 在上述研究基础上，进而讨论复杂的六自由度空间机器人动力学参数辨识 问题。类似地，用上述两种算法分别实现对空间机器人动力学参数辨识。然 而，在辨识中发现采用传统遗传算法容易产生 “早熟 ”现象，导致寻优过程过早 结束，达不到理想的辨识精度。有鉴于此，本文采用小区间生成法、精英保留 策略和大变异操作对原有遗传算法进行改进，并将动力学参数仿真的结果与最 小二乘法的辨识结果相对比，发现在参数矩阵复杂的情况下，遗传算法表现出 明显的优越性。本文还采用最小二乘法针对被捕获的未知物体的动力学参数进 行辨识。 最后，本文利用 matlab 的 GUI 对两关节以及六关节机器人动力学参数辨 识问题进行软件设计，实现了参数辨识输入和输出的界面显示，从而以图形方 式直观地表达了辨识效果，增强了可交互性。 关键词 空间机器人；动力学参数辨识；最小二乘法；遗传算法；软件编制