In context
In 2024, robot-assisted minimally invasive surgery continued to expand, yet accurate control of cable-driven instruments remained challenging because end-effector sensors cannot withstand repeated sterilization. This prompted research into sensorless position estimation and hysteresis modeling.
What was reported
Engineers at Zhejiang Sci-Tech University analyzed the hysteretic behavior of wire rope drives in minimally invasive surgical instruments and proposed an improved Preisach model. The model accounts for cable flexibility, friction, and gear backlash, which cause the end-effector angle to deviate from the motor angle, especially during direction reversals.
To reduce computational complexity, the classical Preisach model was modified by grouping similar relay operators into shared operators with variable thresholds but constant width τ. This significantly cut the number of operators while preserving the linear input-output relationship outside the hysteresis zone.
Model parameters were identified using the multi-objective genetic algorithm NSGA-II, based on data from a single-joint wire rope test platform. Validation showed a maximum error of less than 1°. The method outperformed linear regression, random forest, and neural networks in accuracy, stability, and overfitting resistance.
Why it mattered
This work offered a practical, low-computational solution for sensorless motion compensation in cable-driven surgical tools, potentially improving control precision and hand-eye coordination in robotic surgery without compromising instrument durability.
“The proposed algorithm demonstrates the best comprehensive index, exhibiting high precision, stable results, and low overfitting.”
Source: 《机器人》期刊 (robot.sia.cn) · Published 2024-11-15 · “基于Preisach模型的微创手术器械钢丝绳驱动滞回特性分析与建模”