Advanced Strategies for Robot Manipulators

Amongst the robotic systems, robot manipulators have proven themselves to be of increasing importance and are widely adopted to substitute for human in repetitive and/or hazardous tasks. Modern manipulators are designed complicatedly and need to do more precise, crucial and critical tasks. So, the simple traditional control methods cannot be efficient, and advanced control strategies with considering special constraints are needed to establish. In spite of the fact that groundbreaking researches have been carried out in this realm until now, there are still many novel aspects which have to be explored

Robotics-Assisted Needle Steering for Percutaneous Interventions: Modeling and Experiments

Needle insertion and guidance plays an important role in medical procedures such as brachytherapy and biopsy. Flexible needles have the potential to facilitate precise targeting and avoid collisions during medical interventions while reducing trauma to the patient and post-puncture issues. Nevertheless, error introduced during guidance degrades the effectiveness of the planned therapy or diagnosis. Although steering using flexible bevel-tip needles provides great mobility and dexterity, a major barrier is the complexity of needle-tissue interaction that does not lend itself to intuitive control. To overcome this problem, a robotic system can be employed to perform trajectory planning and tracking by manipulation of the needle base. This research project focuses on a control-theoretic approach and draws on the rich literature from control and systems theory to model needle-tissue interaction and needle flexion and then design a robotics-based strategy for needle insertion/steering. The resulting solutions will directly benefit a wide range of needle-based interventions. The outcome of this computer-assisted approach will not only enable us to perform efficient preoperative trajectory planning, but will also provide more insight into needle-tissue interaction that will be helpful in developing advanced intraoperative algorithms for needle steering. Experimental validation of the proposed methodologies was carried out on a state of-the-art 5-DOF robotic system designed and constructed in-house primarily for prostate brachytherapy. The system is equipped with a Nano43 6-DOF force/torque sensor (ATI Industrial Automation) to measure forces and torques acting on the needle shaft. In our setup, an Aurora electromagnetic tracker (Northern Digital Inc.) is the sensing device used for measuring needle deflection. A multi-threaded application for control, sensor readings, data logging and communication over the ethernet was developed using Microsoft Visual C 2005, MATLAB 2007 and the QuaRC Toolbox (Quanser Inc.). Various artificial phantoms were developed so as to create a realistic medium in terms of elasticity and insertion force ranges; however, they simulated a uniform environment without exhibiting complexities of organic tissues. Experiments were also conducted on beef liver and fresh chicken breast, beef, and ham, to investigate the behavior of a variety biological tissues

Design and control of a multi-axis micro-electro-mechanical system array for coordinated micro-manipulation

Micro-electro-mechanical system design and implementation is a field that has received much attention over the past few decades. These robotic systems with features on the micro-scale have an unparalleled opportunity to change the way scientists interact with and understand micro and nano-scale phenomenon. Their capabilities allow experimentation that cannot be achieved with standard macro-scale equipment. Potential applications range from observing biological processes in living cells, to smart materials that automatically detect microcracks. So far, however, only a few truly successful applications have been realized. One of the most elusive goals in MEMS design is creating a system capable of coordinated motion tasks. This task requires an innovative approach to mechanism design and control. In this work a novel micro-positioning stage is presented that is intended to be implemented in a very large scale array. The stages are actuated by custom optimized electro-thermal-compliant micro-actuators intended for high force applications. These actuators, in combination with mechanical amplification, enable a high degree of mobility which allows a large work area. Furthermore the stage itself has a small foot print to allow a high density of actuators to interact in the common workspace. Control of the stages is realized using vision feedback with Kalman Filtering for high-speed intersample estimation. An iterative learning controller is then used for high precision tracking. This approach gives a high degree of accuracy that is nearly as good as the resolution of the measurement system, and at frequencies that approach the bandwidth of the system --Abstract, page iii