选矸机器人高速并联机构伺服驱动选型研究

Study on selection of the servo drive motor for gangue sorting robot′s high-speed parallel mechanism

为了实现煤矸的高效分选,基于选矸机器人结构及工作原理,在建立并联机构位移、速度、加速度、转矩、等效转动惯量数学模型和选矸运动轨迹规划的基础上,提出了一种用于煤矸分选的三自由度串并混联机器人的伺服电机选型方法:计算分析了选矸过程中机器人主动关节速度、转矩、等效转动惯量和功率的变化分布;针对速度、转矩、等效转动惯量随机构位形改变连续变化的问题,提出根据最大瞬时功率初步选取伺服电机,然后参考关节最大转速和电机允许最大转速选取减速器减速比,结合电机转矩特性曲线进行功能校验的伺服电机选型方法;指出在设计过程中应尽量选取大速比减速器,以减小电机负载惯量比,降低惯量波动干扰,提高系统控制响应速度和运行稳定性。测试和应用结果表明:设计开发的选矸机器人作业周期为1s,横向选矸推力达25kg。该机器人发挥并联机构可实现高速、高刚度的结构特性,结合串联机构工作空间大、结构简单的优势,适于高效煤矸分选,且已成功应用于多条选煤生产线的中、大块矸石分选,长期连续工作运行稳定。研究为机器人伺服驱动系统设计提供了有益的参考。

For effecting high-efficiency separation of coal and gangue,a study is made on the method for selection of the 3-degree-of-freedom servo motor-driven system of the series-parallel gangue sorting robot,based on the robot′s structure and working principle,as well as the mathematic model for displacement,speed,acceleration,torque,and equivalent inertia of the parallel mechanism,and the planning for the gangue sorting motion trajectory.Whereas,the changes and distribution of robot′s active joint velocity,torque,equivalent inertia and power during sorting process are calculated and analyzed.To address the issues regarding the variations of velocity,torque and equivalent inertia accordingly with the changes of configuration of the mechanism,the method for preliminary selecting the servo motor according to instantaneous power,and by reference to the gear′s reduction ratio determined by maximum joint speed and allowable motor speed,and the motor′s function verified by its torque characteristic curve,is proposed.It is pointed out that during the design process,a reducer with a large reduction ration should preferably be selected whenever possible for reducing motor′s load inertia ration and in-terference induced by inertia fluctuation, and enhancing system′s control response speed and operating stability. Results of testing and application show that the developed robot operates with a cyclic time of one second and its capable of imparting to a piece of gangue a lateral thrust force of up to 25 kg. By virtue of the advantages of the parallel mechanism, such as high sorting speed, simple and rigid structure, and large working space, the robot is particularly suitable for making high-efficiency sorting of gangue from coal, and has been incorporated into a number of coal cleaning systems for removal of large pieces of gangue. Practice shows it can work continuously in a stable manner. The work made in the paper may serve as a reference for the design of gangue sorting robot′s servo system.