| In recent years,with the rapid development of science and technology,irregular lifestyles have caused more and more people to suffer from cardiovascular and cerebrovascular diseases.Due to the deficiencies of traditional surgical treatment,such as radiation damage,large postoperative wound,and slow recovery efficiency,the distinct characteristics of minimally invasive surgery enable it to overcome the above short comings.Hence,minimally invasive surgery has become a hot spot in the medical community.The combination of minimally invasive surgery and robotic technology is already a mainstream development trend in the medical community and has broad development prospects.Treating the cardiovascular and cerebrovascular diseases by using the vascular robot is a new attempt.With the assistance of vascular robot,it can greatly reduce the harm caused by traditional surgery.Therefore,the exploration of vascular robot has gradually evolved into an important research direction in the medical community.This article selects the vascular robot as the research object,which has a spiral tail structure and possesses decent dynamic performance.In order to precisely describe the various motion modes of the vascular robot,such as translation,rotation,and pitching,the kinematics and dynamics models of the vascular robot are established.Under the effect of the gravity,the vascular robot will have the motions of sink and drift.An apparent weight compensator is constructed to offset this influence.Based on the developed models and designed compensator,the sliding mode and adaptive sliding mode controllers are proposed,respectively,and the stabilities of these controllers are guaranteed via the stability theory.By conducting comparative simulations,the constructed control approaches have superior ability to meet the working requirements of the vascular robot.In view of the coupling effect between the attitude and trajectory of the vascular robot,the dual quaternion algorithm is adopted to depict the attitude and trajectory simultaneously,so as to establish the kinematics and dynamics models of the integrated attitude and trajectory for the vascular robot.Compared with other motion description methods,modeling the vascular robot via the dual quaternion algorithm can reduce the difficulty of data operations,and the mathematical description of developed models are clearer and more explicit.In the actual situation,the vascular robot will sink owing to the interference of the apparent weight,which is usually neglected in the conventional control methods.Based on the above problems,an apparent weight compensator is designed to offset the known interference by tilting the attitude of the vascular robot up to a certain angle.Therefore,the accuracy,reliability and safety of the precise control for vascular robot can be improved to some extent.Then,the sliding mode variable structure controller is designed to control the attitude and trajectory motions of the vascular robot simultaneously.According to the Lyapunov stability theorem,the system stability of the constructed controller is proved.Linear and curved vascular trajectories are utilized to verify the effectiveness of the controller.Taking into account that in practical operation,the vascular robot is influenced by the real-time denaturing pulsating fluid environment,as well as the difference of various parameters of human blood,the model parameters of the vascular robot have unpredictable variability and uncertainty.In addition,the chattering phenomenon that exists in the sliding mode variable structure controller will degrade its control performance.To deal with these problems,an adaptive sliding mode controller is designed by combining the merits of adaptive control and sliding mode control.The stability of this controller is demonstrated by the Lyapunov function,and linear and curved vascular trajectories are used to confirm the control performance. |
