External Force/Torque Estimation on a Dexterous Parallel Robotic Surgical Instrument Wrist
External Force/Torque Estimation on a Dexterous Parallel Robotic Surgical Instrument Wrist
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DOI：
10.1109/iros.2018.8594326
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
Nural Yilmaz;Merve Bazman;U. Tumerdem
中科院分区：
文献类型：
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作者：
Nural Yilmaz;Merve Bazman;U. Tumerdem
针对机器人手术器械中的刚性连杆并联腕机构，提出了一种新的无传感器力估计算法。该方法利用新的反作用力观测器（RFOB）在关节空间，这是修改后的干扰观测器（DOB）结合神经网络（NN）的逆动力学计算，估计外力作用在电机上。通过使用机器人雅可比矩阵实现笛卡尔空间中的外力/扭矩估计。该算法适用于任何可反向驱动的刚性连杆手腕机构，而不需要力传感器。在本文中，该方法实现了一种新的3度的自由度（DOF）并联机器人手术手腕机构，设计用于高灵巧性（±90度俯仰-偏航旋转，推力运动）和力/扭矩估计。腕关节由3个刚性推拉杆和3个直线电机驱动。在刚性传动和高反向驱动能力的情况下，可以利用所提出的方法从电机位置读数实现外力/扭矩估计。在所制造的仪器原型上进行了几次实验，结果验证了腕部和估计方法的功效，其中俯仰轴上的RMS力/扭矩估计误差值为0.0024 Nm，偏航轴上的RMS力/扭矩估计误差值为0.0043 Nm，推力轴上的RMS力/扭矩估计误差值为0.1866 N。
This paper describes a novel sensorless force estimation algorithm for the rigid link parallel wrist mechanism of a robotic surgical instrument. The method utilizes novel reaction force observers (RFOB) in joint space, which are modified disturbance observers (DOB) combined with Neural Networks (NN) for inverse dynamics calculations, to estimate external forces acting on the motors. External force/torque estimation in Cartesian space is achieved by the use of the robot Jacobian. The proposed algorithm is applicable to any back-drivable rigid-link wrist mechanism without the need for force sensors. In this paper, the method is implemented on a novel 3 degree-of-freedom (DOF) parallel robotic surgical wrist mechanism that is designed for high dexterity (±90 degrees pitch-yaw rotations, thrust motion) and force/torque estimation. The wrist is actuated extracorporally with 3 rigid push-pull rods and 3 linear motors. With a rigid transmission and high back-drivability, external force/torque estimation can be achieved from the motor position readings utilizing the proposed method. Several experiments were performed on the manufactured prototype of the instrument and results validate the efficacy of the wrist and estimation method with RMS force/torque estimation error values of 0.0024 Nm in pitch axis, 0.0043 Nm in yaw axis and 0.1866 N in thrust axis.