闭链弓形五连杆翻滚机构越障性能研究

发布时间：2018-02-08 19:46

本文关键词： 闭链弓形五连杆质心运动学模型越障能力匀速爬坡运动规划　出处：《武汉纺织大学》2017年硕士论文　论文类型：学位论文

【摘要】：本论文针对在非结构环境下提出了具有圆弧外轮廓的闭链弓形五连杆机构。闭链弓形五连杆由五个相同的弓形杆件模块首尾串联而成,通过配重法使每个弓形杆件模块质量mi相等且质心位置处于相邻模块关节连线的中点。当五个关节角均为108o时,闭链弓形五连杆的外轮廓为圆形,质心与形心重合。单根杆件触地时,依靠质心偏置产生的重力矩机构能够实现平面准静态滚动。为了便于分析与表达,通常将障碍物地形简化为斜坡、台阶、连续台阶、凸台、沟道等具有典型特征的地形,本文选择台阶和斜坡障碍物地形考查闭链弓形五连杆运动性能。首先对闭链弓形五连杆的准静态翻滚过程进行研究,进行准静态翻滚运动学分析;分析越障过程中的运动约束和几何约束,建立闭链弓形五连杆机构的最大越障分析模型,利用数值算法获得了最大越障高度随接触角和关节圆半径的变化曲线。根据质心可行域边界曲线内凹的特点,依照行程最短策略采用切线法来规划越障过程中系统质心运动路径,进而利用运动学逆解得到主动关节轨迹,通过受力关系解算出了准静态越障过程最大静摩擦系数的变化曲线。其次,建立系统爬坡受力分析模型,并在主动关节角爬坡约束下求解出爬坡的坡度表达式,利用数值算法获得了坡度最大与翻滚角的曲线图,通过受力关系解算出了最大静摩擦系数的变化曲线。对恒定质心偏距匀速爬坡进行运动规划,进而解算主动关节轨迹。最后,通过样机实验验证了越障和爬坡过程的分析结果的正确性。闭链弓形五连杆准静态平面翻滚过程的质心运动学模型的建立与求解为研究准静态越障过程和恒定质心爬坡过程提供了理论基础。
[Abstract]:In this paper, a closed chain arched five-bar mechanism with outer arc profile is proposed under unstructured environment. The closed chain arched five-bar is composed of five modules of the same arched bar, the first and the last of which are connected in series. The mass mi of each module is equal and the center of mass is at the midpoint of the connection between the adjacent joints. When the angle of the five joints is 108o, the outer contour of the five-bar is circular. When a single member touches the ground, the weight moment mechanism produced by the deflection of the center of mass can realize the plane quasi-static rolling. For the sake of analysis and expression, the obstacle terrain is usually simplified as slope, step, continuous step, convex platform. In this paper, the terrain with typical characteristics, such as channel, is chosen to examine the kinematic performance of the closed chain arch five-bar. Firstly, the quasi-static rolling process of the closed chain arch five-bar is studied, and the quasi-static rolling kinematics analysis is carried out. The kinematic and geometric constraints in the process of obstacle surmounting are analyzed, and the maximum obstacle analysis model of the closed chain arched five-bar mechanism is established. The curve of maximum obstacle height with contact angle and radius of joint circle is obtained by numerical method. According to the concave characteristic of boundary curve in the feasible region of centroid of mass, According to the shortest stroke strategy, the tangent method is used to plan the motion path of the center of mass in the process of obstacle crossing, and then the trajectory of the active joint is obtained by using the inverse kinematics solution. The variation curve of maximum static friction coefficient during quasi-static obstacle surmounting process is calculated by the solution of force relation. Secondly, the analysis model of system climbing force is established, and the slope expression of climbing slope is obtained under the constraint of active joint angle. The curve of maximum slope and roll angle is obtained by using numerical algorithm, and the variation curve of maximum static friction coefficient is calculated by force relation solution. The motion planning of constant centroid deviation and constant velocity climbing is carried out, and then the trajectory of active joint is calculated. The correctness of the analysis results of obstacle surmounting and climbing process is verified by prototype experiment. The kinematics model of centroid in the quasi static plane rolling process of closed chain bow is established and solved for the study of quasi static obstacle surmounting process and constant mass. The core climbing process provides the theoretical basis.
【学位授予单位】：武汉纺织大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP242

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