【作者】 李占贤；

【导师】 黄田；

【作者基本信息】 天津大学 ， 机械制造及其自动化， 2004， 博士

【摘要】 本文研究了一种可实现二平动自由度并联机构的概念设计、尺度综合、伺服电机参数预估、控制器参数整定、运动学标定等关键技术,开发了一台可充电电池质量高速自动分拣机械手产品化样机,取得了如下创造性成果: 利用平行四边形的性质,提出一种具有我国自主知识产权,可实现二平动自由度的全铰接并联机构---Diamond 机构。该机构因采用转动副,伺服电机安装在机架上,故制造成本低,且利于实现高速运动。将该机构与一单自由度进给机构串接可构成三平动自由度混联机械手,因此特别适用于在一个平面内需要高速运动,而在与该平面正交方向需要长(短)距步进或缓进的场合。提出了一种全域综合性能指标。该指标兼顾了雅克比矩阵条件数全域均值和波动量间的矛盾,同时通过引入传力特性、工作空间/机构体积比、以及工程可行性等一系列约束条件,进而实现了机构尺度的最优综合。提出一种确定伺服进给电机参数的方法。该方法借助奇异值分解原理,建立了关节变量上界与单位操作变量间的映射关系,进而可快速预估出伺服电机参数。提出一种对固定增益PID调节器进行参数整定的有效方法。该方法采用CHR扰动抑制算法整定速度环参数,并根据电控与机械子系统匹配原则,实现位置环增益整定。上述方法与速度前馈功能,有效地提高了机械手的速度、轨迹精度和运动稳定性。提出一种首先辨识主动臂回零转角误差,而后再辨识其它几何参数误差的分层递阶运动学标定方法。理论与工程实践证明,该方法具有很强的鲁棒性。基于上述研究成果,建造出一台可充电电池质量高速自动分拣机。样机具有结构简单、制造成本低、生产率高等优点。手爪最高速度可达4 .5m/s,最大加速度达60 m/s2,点—点定位精度达0 .05mm。另台样机已经出口英国Warwick 大学,用于科研与教学。更多还原

【Abstract】 This dissertation is focused upon the development of a complete theoretical package in terms of the conceptual design,dimensional optimization synthesis,servomotor parameters estimation,control parameters setting and kinematic calibration of a novel 2-DOF translational parallel robot for rapid pick-and-place operations. As a result, a prototype machine for automatic sorting of rechargeable batteries has been developed. The following creative works have been completed. Utilizing the properties of parallelograms, a 2-DOF revolute-jointed translational parallel robot patented with the name Diamond has been proposed. The light-weight component design and the base-mounted actuator arrangement allow the robot to achieve very high velocity and acceleration. This device can also be integrated with a 1-DOF feed mechanism, enabling a 3-DOF translational hybrid robot to be created. The integration is particularly useful for transporting workpieces at very high speed in a plane together with a relatively slow or step-by-step long distance motion in the direction normal to that plane. It has been found that the mean value of condition number of the Jacobian matrix is not suitable for evaluating the kinematic performance of the parallel mechanisms driven by external actuators. A global and comprehensive cost function is proposed by considering both the mean value and fluctuation of the condition number of Jacobian matrix. Meanwhile, a set of appropriate constraints has been considered in terms of the force transmission behavior, the workspace/machine volume ratio, and the feasibility in practical implementation. With the aid of the principle of virtual work, the dynamic model of the robot has been formulated. An approach to estimate the servomotor parameters is proposed using the singular value decomposition technique, resulting in the mapping function between the maximum value of joint variables and the unit operation variables. This makes it possible to the upper bounds of the servomotor parameters to be estimated in an effective manner. These parameters include the moment of inertia, the maximum speed, torque, and power. A method for the fixed-parameter PID controller tuning is proposed by taking into account of the nonlinearity and structural stiffness. The method can be implemented by two steps, (1) Tune the PID parameters of the velocity control loop by the CHR method, and (2) Tune the position control gain according to the matching principle of the dynamic characteristics of the control and mechanical subsystems. It has also been shown that the velocity tracking error can be dramatically reduced by using the feedforward control strategy. An effective kinematic calibration approach has been presented by taking the initial position of the reference point of the moving platform as the origin of the calibration frame. The method can be implemented by identifying the home errors of the active proximal links in the first place and followed by identifying the rest geometrical errors. The above outcomes have been used for the development of a prototype machine for automatic sorting of rechargeable batteries. It has been shown that the device is of simple structure, low cost, and high productivity. The gripper velocity is up to 4.5m/sec and the acceleration to 60m/sec2. The point-to-point positioning accuracy is 0.05mm. Another prototype has been developed for the University of Warwick in the UK for teaching and research.更多还原