機器人雙指抓取接觸分析

Contact force analysis on two-fingered robot grasping

陳俊儒(Jiun-Ru Chen)

指導教授 ： 劉昭華

淡江大學/工學院/機械與機電工程學系碩士班/碩士(2011年)

https://doi.org/10.6846/TKU.2011.00333

摘要

本論文提出兩指抓取圓球之逆向動力學的力量分析程序，亦即在物體的線性加速度及角加速度皆已知的情況，求出手指的挾持力。由於剛體模型會造成不確定性，本研究建議加入彈性變形，利用赫式接觸之力與位移關係式、相容方程式、以及運動方程式合併解題。本文針對二指抓取彈性球體時的情況，從事以下兩種情況的逆向動力分析:第一，針對物體的線性加速度及角加速度為已知，且兩指間的相對位移向量亦為已知的情況，求得挾持力的數值解。由於運動方程式具一階不確定性，這表示可選取一個抓取力當作主要變數，而其他的抓取力都表示成這個力的函數，因此數值程序僅包含單一未知數，可快速求出接觸力。第二，針對特定的線性加速度及角加速度，若兩指間的夾緊方向亦為已知，本文可求出手指不會滑動所需的最低夾緊量、以及這時的接觸力，而且是以閉合解呈現。

關鍵字

二指抓取 ； 接觸力分析 ； 夾緊位移量

並列摘要

In this thesis a procedure for inverse dynamics analysis of two-fingered grasping of a sphere is proposed. Contact forces may be found for given linear and angular accelerations of a spherical body. Elastic force-displacement relations predicted by Hertz contact theory are used to remove the indeterminancy produced by rigid body model. Two types of inverse dynamics analysis are performed for two-fingered grasping of a sphere. Firstly, as linear and angular accelerations, as well as the relative displacement vector of the finger tips, are given, grasping forces may be obtained by a numerical procedure. In this procedure one degree of indeterminancy produced by the equations of motion are utilized. Specifically, one particular contact force may be chosen as the principal unknown, and all other contact forces are expressed in terms of this force. The numerical procedure is hence very efficient since it contains only one principal unknown. Secondly, for given linear and angular accelerations, if the relative grasping direction of the two fingers is also known, then the closed form solution for the minimum tightening displacement for sliding not to occur can be obtained.

並列關鍵字

Two-fingered grasping ； Contact force analysis ； tightening displacement

參考文獻

[32] 成怡，機械手臂抓取接觸力分析，淡江大學機械與機電工

International Conference on Robotics and Automation,

p 396-401, 1988.

795-800, 2004.

Grasp-based Visual Servoing for Gripper-to-object