Model Based Deformable Object Manipulation Path Planning and Position Control

Abstract

<p>A deformable object is a body that can undergo an alteration in shape and dimension as a result of external interactions. This characteristic makes deformable object handling considerably more difficult than handling rigid objects, which allow for the independent control of object grasping and manipulation. In the case of a deformable object, the grasping and manipulation interfere with one another, since a large enough force on the object may change its shape and location. One solution to this problem is the use of deformable object models. Models can provide an insight to the behavior of a deformable object subjected to various interactions with its environment. Lately, the use of deformable object models has received much attention from the industrial and medical communities.<br /><br />This thesis addresses the use of a deformable object model, developed using the mesh free Reproducing Kernel Particle Method RKPM, to aid in the accurate control of soft object manipulation path planning procedures and target stabilization during needle insertion procedures. Also, the deformable object is used as a part of an integrated system to control the manipulation of a physical object, using a robotic tool under position feedback from a stereoscopic camera.<br /><br />The results present a comparison between two different integration methods used to solve the deformable object model; The Gaussian Quadrature and a more efficient method referred to as the Collocated method, which is explained in Chapter 3. In both cases, the accuracy values of the results were comparable. A preliminary study was successfully completed using a coarse and refined object model to show a virtual concept of the physical system prior to its development. Using markers to dictate the performance of a physical object corresponding to the simulated object, experimental results were attained for a planar deformable object. Successful path following tasks were accomplished using the physical deformable object.<br /><br />Further, the target stabilization method proved to be successful in reducing the movement of a target with respect to the insertion direction of the needle in the tissue. The static paddle approach used the criteria of choosing the optimal paddle based on the highest reduction in target lateral movement, which showed to be case specific. The dynamic paddle approach was formulated to reposition the target back to its original position and was more robust to object characteristic changes.</p>