Design Of Resonant Tactile Sensor Measurement System Based On Double Closed-loop Control

With the development of robot technology,robots are expected to be widely used in the medical field.Tactile sensing technology is one of the key technologies for medical robots.Currently,research on tactile sensing technology mainly focuses on contact force measurement,while the development of soft tissue hardness measurement technology is seriously lagging behind.This phenomenon greatly limits the application of robots in the medical industry,and there is an urgent need for medical robots to improve their tactile sensing capabilities.In response to this need,this paper presents a tactile sensor system for medical robots,which significantly enhances the potential for medical robots to perform tasks such as simulating palpation,sensing during minimally invasive surgery,and monitoring during radiofrequency ablation surgery.The specific research work is as follows:1.A tactile sensor measurement system based on the resonance principle applied to medical robots is designed,which can measure soft tissue hardness and contact force simultaneously;This system can simultaneously measure soft tissue hardness and contact force.The equivalent circuit model of the sensor system was established based on the principle of electromechanical equivalence,and the correctness of the equivalent circuit model was verified using ABAQUS finite element simulation software.The feasibility of the hardness measurement scheme was theoretically analyzed and demonstrated using the equivalent circuit model.The corresponding relationship between soft tissue hardness and the frequency shift of the system resonance was simulated using the finite element model of the tactile sensor system,and the corresponding curve was drawn.The simulation results show that the designed tactile sensor system has good hardness discrimination ability within the range of human soft tissue hardness.2.The drive measurement module is the core component of the tactile sensor system.The current common practice is to design the drive and measurement modules separately,with the drive circuit using open-loop or single closed-loop drive,and the measurement module mainly using frequency tracking circuits based on phase-locked loops.However,this scheme has a complex structure that is not conducive to miniaturization and has low measurement accuracy.To address this issue,this paper proposes a double closed-loop drive measurement module that combines a stable amplitude control loop with a frequency tracking loop.The mathematical model of the drive measurement module was established using Simulink software in MATLAB,and simulation calculations were performed using this mathematical model.The simulation results show that the module has a high level of control accuracy.3.Based on the design scheme,a physical tactile sensor system was constructed,and a human-machine interaction platform for the tactile sensor measurement system was designed using Lab VIEW software.The contact force and hardness measurement curves of the tactile sensor system were calibrated using a silicone model sample to simulate biological soft tissue,and the hardness of silicone samples within the range of biological tissue hardness was measured.The measurement results showed that the sensor system met the expected design requirements and could effectively identify the hardness of biological soft tissue while perceiving contact force.