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针对微创手术机器人通常采用的独立PD控制或基于重力补偿的PD控制,都必须预先设定好相应的PD常数,不能随刀具所受有效外载荷而进行自适应调节,从而影响了机器人的定位精度的问题。提出了一种基于计算力矩的控制模型,在拉格朗日动力学模型基础上引进控制量使机器人系统线性化,并且将静力学分析结果作为反馈信号,完成外载荷作用下的轨迹精确控制。在Matlab软件中建立机器人物理模型及控制模型,仿真比较了重力补偿PD控制与基于计算力矩控制所得刀具末端的位置偏差,证实了该模型具有良好的自适应能力。仿真结果也表明该方法的定位精度能够达到0.4 mm以上。
For the independent PD control or gravity-compensated PD control usually used in minimally invasive surgical robots, the corresponding PD constants must be preset and can not be adjusted adaptively with the effective external load on the tool, thus affecting the positioning of the robot Accuracy problems. A control model based on computational torque was proposed. Based on the Lagrangian kinetic model, the control volume was introduced to linearize the robot system. The static analysis results were used as the feedback signal to complete the trajectory precise control under the external load. The robot physics model and control model are established in Matlab software. The gravity compensation PD control and the position deviation of tool tip based on the calculation of moment control are simulated and compared, and the model has good self-adaptability. Simulation results also show that the method can achieve the positioning accuracy of 0.4 mm or more.