Achieving commutation control of an MRI-powered robot actuator

Actuators that are powered, imaged, and controlled by magnetic resonance (MR) scanners could inexpensively provide wireless control of MR-guided robots. Similar to traditional electric motors, the MR scanner acts as the stator and generates propulsive torques on an actuator rotor containing one or more ferrous particles. Generating maximum motor torque while avoiding instabilities and slippage requires closed-loop control of the electromagnetic field gradients, i.e., commutation. Accurately estimating the position and velocity of the rotor is essential for high-speed control, which is a challenge due to the low refresh rate and high latency associated with MR signal acquisition. This paper proposes and demonstrates a method for closed-loop commutation based on interleaving pulse sequences for rotor imaging and rotor propulsion. This approach is shown to increase motor torque and velocity, eliminate rotor slip, and enable regulation of rotor angle. Experiments with a closed-loop MR imaging actuator produced a maximum force of 9.4 N

Study of Needle Insertion Parameters of Human Body Tissue for Surgical Operations

The thesis introduces the study on needle insertion during the laboratory experiment. The percutaneous needle insertion is performed several times in day to day life. Manually placement of needle in the tissue may cause damage inside the body sothe thesis presents the existing methodology of needle insertion and researched methodology in our laboratory. It shows the proper way of needle placement and which parameters are necessary to keep in mind when perform the needle insertion. It deals with the proper way of needle insertion, minimise the deflection of needle inside the tissue and gives an idea of reduction in deformation of tissue. The test procedures and experimental setup provide an understanding on the mechanics of needle placement and the design improvement of insertion instruments.The experimental analysis optimize the results of operative parameters of needle when it insert in the tissue like needle translation motion during the insertion, needle rotational motion during insertion, angle of needle insertion and force acting on the needle when it inserted in the tissue. The optimize results provide a brief knowledge for the surgeons about the needle behaviour during the insertion in soft tissue so surgeons are pre imagined the situations by which they would going through during the operation. The model enhances the quality of insertion by presenting the optimize model for parameters of needle insertion. In most of the insertion operations accuracy and precision is important parameters which must be kept in mind by the surgeons when they performed the insertion of needle inside the tissue so this is study is relevant for them to get the accuracy and precision in work. The aim of this research is to present standard methodology for needle insertion which can be possible by experimental analysis of needle insertion in laborator