Geometric Control Theory For The Puncture Of Steering Flexible Needle

As minimally invasive techniques involved in clinical medical treatment,needle puncture is widespread in many procedures,including percutaneous procedures requiring therapy delivery to or sample removal from a specific location.When flexible needle with a bevel tip pushes through soft tissue,the asymmetry of the tip causes the needle to bend,and could reach the target which the traditional needle can not reach.So the research of path planning of flexible needle is significant for accurate puncture.In this thesis,the path planning and the adaptive output feedback tracking control are discussed for the flexible needle.Firstly,under the assumption of rigid tissue,the path planning of flexible needle in 2D and 3D environment with obstacles are discussed.In 2D,to choose the tangent from initial point to target point,and calculate the coordinates of the tangents,then the circular arcs passing through initial point?the tangent point and target point is the feasible path,and the shortest arc is the optimal path.In 3D,based on the Rapidly-exploring Random Trees(RRTs)method,a set of feasible paths are found,then an optimal path which could avoid obstacles by minimizing the optimization criterion is given.Simulation results show that both of the two path planning methods could find the optimal paths,which illustrate the effectiveness of the path planning methods.Secondly,the flexible needle can be feedback linearized via a transformation of state and input coordinates.While subjected to parametric uncertainty,the system is transformed to adaptive tracking form by a filtered transformation.The adaptive output feedback tracking controller is designed to track time-varying reference output signals,which realize the tracking between flexible needle and the target point.