Soft Robot Heart-tracking System For Surgery

With the development of robot science and technology,soft robot has became more and more popular.Soft robots are made of flexible and elastic materials.Compared with traditional rigid robots,soft robots have the advantages of deformation ability,movement ability and safety.Meanwhile,in the medical field,the research on surgical robots has become a hot topic.Therefore,in this paper,we designed a robot system that can perform surgery with the beating heart.The difficulty of the heart tracking system of soft surgery robot is that the modeling of soft robot is more complicated,because the soft robot arm will deform under the influence of gravity,so the traditional rigid robot modeling method cannot accurately calculate the pose of soft surgery robot,thus affecting the control precision.At the same time,the movement of the heart is constantly changing,making it difficult to track.The soft robot in this research is made of silica gel and is driven by cables.it is inspired by the way the tentacles contract.The robot is embedded with four driving cables,which are connected with the ring at the end of the soft robot.The length of the cable can be changed by the steering gear,thus causing deformation of the soft robot.In this paper,a soft robot system for heart tracking is designed,which can make use of the deformability of soft robot to track the movement of target points on the heart surface when the heart is beating during heart surgery.Compared with the rigid arm,the deformation of the soft arm is not only related to joint variables,but also affected by gravity.The use of the traditional constant curvature model will lead to the imprecision of the soft arm model,thus affecting the accuracy of control.In order to solve this problem,the effect of gravity is taken into account in the modeling of soft arms in this paper.Based on the Cossrat beam theory,the force deformation model of soft arms is established,so that the deformation and terminal pose of soft arms under the influence of gravity can be calculated more accurately.On this basis,the embedded binocular camera at the end of the soft arm can calculate the coordinates of the target point on the heart surface in the camera coordinate system,and then the three-dimensional position of the target point on the heart surface in the soft robot base coordinate system can be calculated through the force deformation model to obtain the heart motion information.In order to solve the problem of the change of heartbeat frequency,this paper models the coordinates of the target points on the heart surface according to the collected data,so as to predict the movement of the target points in the future time domain,which serves as the expected trajectory of the track tracking.At the same time,the parameters of the heartbeat model are updated in real time with the operation of the system,so that the tracking system can adapt to the changes of the heartbeat frequency.Finally,a model predictive control system is designed to control the desired track of the soft robot,and the simulation and experiment show that the algorithm can reduce the tracking error and adapt to the change of the heart beat pattern.