A passivity based control methodology for flexible joint robots with application to a simplified shuttle RMS arm

The main goal is to develop a general theory for the control of flexible robots, including flexible joint robots, flexible link robots, rigid bodies with flexible appendages, etc. As part of the validation, the theory is applied to the control law development for a test example which consists of a three-link arm modeled after the shoulder yaw joint of the space shuttle remote manipulator system (RMS). The performance of the closed loop control system is then compared with the performance of the existing RMS controller to demonstrate the effectiveness of the proposed approach. The theoretical foundation of this new approach to the control of flexible robots is presented and its efficacy is demonstrated through simulation results on the three-link test arm

Sampled data analysis of a computer-controlled manipulator

A comprehensive sampled data analysis of a computer-controlled manipulator is presented in terms of root loci for gain selection and transient responses to step input functions. All parameter values and their derivations where applicable were tabulated. The analysis, while quite specific, uses normalized gain parameters, which allows the results to be applied to any similar system regardless of individual hardware parameter values

Haptics-Enabled Teleoperation for Robotics-Assisted Minimally Invasive Surgery

The lack of force feedback (haptics) in robotic surgery can be considered to be a safety risk leading to accidental tissue damage and puncturing of blood vessels due to excessive forces being applied to tissue and vessels or causing inefficient control over the instruments because of insufficient applied force. This project focuses on providing a satisfactory solution for introducing haptic feedback in robotics-assisted minimally invasive surgical (RAMIS) systems. The research addresses several key issues associated with the incorporation of haptics in a master-slave (teleoperated) robotic environment for minimally invasive surgery (MIS). In this project, we designed a haptics-enabled dual-arm (two masters - two slaves) robotic MIS testbed to investigate and validate various single-arm as well as dual-arm teleoperation scenarios. The most important feature of this setup is the capability of providing haptic feedback in all 7 degrees of freedom (DOF) required for RAMIS (3 translations, 3 rotations and pinch motion of the laparoscopic tool). The setup also enables the evaluation of the effect of replacing haptic feedback by other sensory cues such as visual representation of haptic information (sensory substitution) and the hypothesis that surgical outcomes may be improved by substituting or augmenting haptic feedback by such sensory cues

Modelling and control of a robotic manipulator subject to base disturbances

This thesis presents the modelling and control of a high gear ratio robotic manipulator mounted on a heavier moving base which is subject to base disturbances. The manipulator motion is assumed not to affect the base motion. The problem of a robotic manipulator on a non-inertial base can be applied to operation on sea vessels or all-terrain vehicles, where the base motion is unknown and cannot be used as a feed-forward signal to the model. A dynamic model is derived for the PA10-6CE manipulator with the assumption of a fixed base and the model terms are analysed numerically when comparing the simulation and experimental results. Based on the obtained results a set of model based controllers is compared to a basic proportional and derivative type controller to evaluate the trajectory tracking gains and trade-offs. The dynamic model is extended to the case of a manipulator on a moving base and numerical comparisons of simulation and experimental results are used to verify the model validity and the significance of the various model terms. From the results of this study a set of model based controllers is obtained. A novel adaptive scheme is then proposed for compensation of an unknown and varying gravity acceleration vector acting on the manipulator base. Controllers based on using an additional sensor output are compared with static and adaptive gravity controllers and the latter proved to be superior in terms of trajectory tracking performance