The kinematic model parameter deviation is the main factor affecting the positioning accuracy of neurosurgical robots. To obtain more realistic kinematic model parameters, this paper proposes an automatic parameters identification and accuracy evaluation method. First, an identification equation contains all robot kinematics parameter was established. Second, a multiple-pivot strategy was proposed to find the relationship between end-effector and tracking marker. Then, the relative distance error and the inverse kinematic coincidence error were designed to evaluate the identification accuracy. Finally, an automatic robot parameter identification and accuracy evaluation system were developed. We tested our method on both laboratory prototypes and real neurosurgical robots. The results show that this method can realize the neurosurgical robot kinematics model parameters identification and evaluation stably and quickly. Using the identified parameters to control the robot can reduce the robot relative distance error by 33.96% and the inverse kinematics consistency error by 67.30%.
运动学模型参数偏差是影响神经外科手术机器人精度的主要因素。为获得更精确的模型参数,本文提出一种自动参数辨识及评价方法,首先基于运动学回路法建立全套神经外科手术机器人运动学参数辨识方程;并设计多次摇尖策略匹配末端工具与测量靶标坐标系;同时提出相对距离误差和逆解重合误差用于辨识精度评价;最后构建自动化参数辨识和精度评价系统并用于实验室原型机和实际神经外科手术机器人参数辨识实验。研究结果表明,本方法可以稳定自动地实现运动学模型参数辨识和评价,使用辨识后参数控制机器人可将相对距离误差平均降低 33.96%,逆解重合误差平均降低 67.30%。.
Keywords: absolute positioning accuracy; parameter calibration; robotic arm; stereotactic.