Study On The System Of The Robot-Assisted Flexible Needle Insertion Into Soft Tissue

In recent years, the incidence rate of cancer rapidly increased because of the factors such like continuously serious environment pollution, heavy working burdens on individuals, low immunity problems from sub-health, etc. Therefore,minimally invasive interventional treatments are widely applied to living cancer therapy, in that the treatments are much stronger at targeting, causing lower trauma,without toxic side-effect, safer and more reliable. The insertion is one of the most widely used surgical techniques in the clinical medicine area. Traditional insertions operations are completed by using rigid needle linear motion. But the path is limited,and the target location errors happen with rigid needle natural deformation, which means that the treatments effects are heavily influenced. In order to solve this problem,the flexible needle insertion is proposed by the researchers. Compared with rigid needle insertion, flexible needle accomplished insertion by using the curvilinear motion. It can deform itself to avoid obstacles like skeleton, blood vessels and the other organs of human body. As a result, the target positions can be reached flexibly and precisely.The paper discuss the issue that use robot to help the flexible needle insert into soft tissue. Path planning of the flexible needle insertion is focused with cooperation between humans and robots, based on the demand of clinical medicine. The robotassisted system for the flexible needle insertion into soft tissue is established. So the doctor can easily increase the controlling and implementation ability to the insertion path by combining the empirical adaptability of human with the precise control of robot.And the problem that people are difficult in controlling flexible needle insertion can be solved. What's more, the system also solves the bad adaptive for the autonomous robot.Meanwhile, the paper offers the theoretical basis and basic method for the clinical application of robotic assisted flexible needle insertion technique is created.Firstly, the kinematical model for robot-assisted flexible needle insertion into soft tissue is built. And the principle and the motion characteristics of flexible needle insertion is considered as continuous arcs with variable radiuses based on the unicycle model. The results for the insertion experiments of simulating flexible needle in soft tissue show that the model is accurate and advisable, and it can also help to lay a foundation for the planning path of the flexible needle.Secondly, the algorithm of the path planning has made thorough research to the robot-assisted flexible needle insertion into soft tissue based on the application of clinical medicine. The path planning algorithm for flexible needle insertion into softtissue is summarized briefly. It mainly analyzes the basic theory and characteristics of the path planning algorithm based on Rapidly-exploring Random Tree(RRT). Aiming at solving the problem that traditional RRT algorithm does not consider the kinematical model of flexible needle insertion system, the path searched is not optimal, and it does not relate to the study of the insertion environment. So the improved Rapidly-exploring Random Tree(RRT) is proposed. The process and characteristic of improved RRT algorithm is described in detail. Then the experimental study is carried out in view of the path planned for the flexible needle by MATLAB.After that, the prototype of the robot-assisted flexible needle insertion system is developed. The overall plan and the specific structure of the insertion mechanism for the robot- assisted flexible needle insertion system are designed. And the design of lower computer control system is analyzed. It provides an experimental platform for the experiment of the robot-assisted flexible needle insertion.Finally, the experimental study is carried out based on the theory cited above. The model is made to simulate the soft tissues of the body. Then the experiment for simulating the flexible needle insertion is made, in order to validate the path planned by the robot of the flexible needle insertion into soft tissue. The experimental data and figure are collected and sorted. The experiment results and the error causes are analysed.