基于计算力矩的微创手术机器人控制

Minimally Invasive Surgical Robot Control Based on Computing Torque

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。

Minimally invasive surgical robots are usually controlled by the method of independent PD or the PD model based on gravitycompensation. However, both of ways require setting the constants of PD in advance, and the constants can＇ t change adaptively with the external load which operation tool endures. So the positioning accuracy of robots is influenced. According to the problem, a control model based on computing torque was proposed. One control variable was introduced to linearize the system of robot based on lagrange dynamics model, and the results of static analysis were used as feedback signal. Thus the precision control of trajectory under the external load was carried out. The physical model and control model were built in matlab software and then simulation was made. The position deviation with PD control based on gravity compensation and that with the control model based on computing torque were compared through the results of simulation. What＇s more, the favorable adaptive ability of the control model was confirmed and the experimental results also indicated that the positioning accuracy could reach 0. 4 mm.