Minimally invasive surgical robotic systems established the foundation for precise and refined surgery, and the intelligentization of robotic systems is an important direction for future development. Among the methods of intelligentization, microinstrument external force sensing is an open and challenging research area. Force sensing information is used not only to ensure that surgeons apply the appropriate amount of force but also to prevent unintentional tissue damage. Because a microinstrument is a compact and small-sized construction, indirect force sensing method instead of the integration of sensors into the microinstrument is used, yielding better biocompatibility, sterilizability and monetary cost savings. This paper focuses on microinstrument-tissue contact force sensing, and the microinstrument used is a three degrees of freedom cable-driven manipulator. A contact force estimation strategy based on the differences in cable tension is established with consideration of the kinematics, dynamics and friction of the manipulator. A principle prototype of a surgical microinstrument force measurement system is developed, and then zero-drift, hysteresis and force loading experiments are studied. Based on the experimental data of the force loading experiments, the relationship between cable tension and contact forces is established by using a bidirectional long short-term memory plus multilayer perceptron network. The results show that the L2 cost of the network in the training set converges to 0.006 and that the RMSE of the network in the testing set converges to 0.053, and the network can meet the measurement requirements without overfitting. Therefore, the indirect force estimation method is a viable method of measuring forces of cable-driven microinstrument and can be used to integrate force sensing information into surgical robotic systems to improve the operability of surgical robots.

中文翻译：

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使用BLSTM–MLP网络基于电缆张力的微仪器接触力传感

微创手术机器人系统为精确和精细的手术奠定了基础，而机器人系统的智能化是未来发展的重要方向。在智能化方法中，微仪器外力传感是一个开放且具有挑战性的研究领域。力感应信息不仅用于确保外科医生施加适当的力，而且还可以防止意外的组织损伤。因为微仪器是紧凑且小巧的结构，所以使用间接力感测方法而不是将传感器集成到微仪器中，从而产生了更好的生物相容性，可灭菌性并节省了金钱。本文着重介绍微器械与组织的接触力传感，所用的微型仪器是一个三自由度的电缆驱动机械手。考虑机械手的运动学，动力学和摩擦力，建立了基于电缆张力差异的接触力估算策略。研制了一种手术用微仪器测力系统的原理样机，然后研究了零漂移，磁滞现象和力加载实验。根据力加载实验的实验数据，通过使用双向长短期记忆加多层感知器网络，建立电缆张力和接触力之间的关系。结果表明，训练集中网络的L2成本收敛到0.006，测试集中网络的RMSE收敛到0.053，网络可以满足测量要求而不会过度安装。因此，间接力估计方法是一种测量电缆驱动的微仪器的力的可行方法，可用于将力感测信息集成到手术机器人系统中，以提高手术机器人的可操作性。