Richard Hurteau

Laparoscopic surgery assisted by a robotic cameraman: concept and experimental results

Laparoscopic surgery is a new type of approach involving the use of a laparoscopic camera and special instruments which are inserted into the abdominal cavity through the abdominal wall. Over the last five years, a variety of complex abdominal surgical interventions have been developed and are now performed according to the minimally invasive surgery principle. In this article, a surgical procedure for a laparoscopic cholecystectomy (gallbladder removal) is presented that involves a robotic assistant. The robot manipulates the laparoscope and provides the video image as it moves into the abdominal cavity. The robot acts as a cameraman and replaces the surgical assistant. The concept of a robotic assistant is presented and the various modifications made to the robot are described. A motion control strategy permits easy teleoperation of the robot. Surgical interventions have been successfully performed, first on animals and then on 8 patients.<<ETX>>

Friction and Stick-Slip in Robots: Simulation and Experimentation

This paper proposes an algorithm for joint friction in robotmanipulator simulations. The model includes an appropriaterepresentation of the behaviour at low speed and, especially, thestick-slip process. The concept of the model is introduced through twosimple examples. The method is then extended to more complex multibodysystems and, in particular, to robot manipulators. It is furthersynthesized into a numerical algorithm for computer simulations. Thealgorithm is experimentally validated using a two-degrees-of-freedomplanar robot moving in the vertical plane. Free motions resulting fromknown initial conditions were successfully reproduced.

Optical guidance system for underground mine vehicles

In underground mines, the operation of loading, hauling, and dumping the ore is a repetitive task, performed by LHD (load-haul-dump) vehicles. The operators of these vehicles are subjected to high levels of noise and vibration, and are exposed to hazardous situations. To improve the safety of operators and their productivity, an optical guidance system adapted to the hostile environment of underground mines has been developed. The physical guideline consists of a high-efficiency optical reflector, and is installed on the back of a mine drift to resist corrosion and frequent blasting. An optical guideline detector, consisting of a camera and an artificial vision system, is used to measure the deviation of the vehicle from the guideline. The performance of the system is analyzed by simulated and by experimental test on a small-scale electric vehicle. Field tests have shown that the optical guidance system has the capability to guide vehicles in a mining environment.<<ETX>>

Path tracking control of tracked vehicles

A path tracking control algorithm for tracked surface drilling machines is presented. The general dynamic model of such vehicle is simulated including track-soil interactions. The controller is based on feedback linearization of the equations with feedforward friction compensation. It linearizes the complex force-slip relationship to relate the states of the system to the inputs. The controller based on simplified models is applied to the detailed simulated model of the vehicle. The result is an accurate control of the lateral offset and forward velocity error along a path.

Experimental stabilization of tractor and tractor-trailer like vehicles

An experimental study of recently proposed algorithms for the stabilization of autonomous vehicles (articulated and non-articulated) is carried out. The idea is to investigate extent by which experimental behavior is in agreement with convergence, stability and robustness properties that are predicted by theory and simulation tests. The study has been conducted using a test bench made of the ensemble of a modified version of a commercial mobile robot and of a modified version of the accompanying commercial software environment. The algorithms under consideration are based on exact input-output linearization, Lyapunov theory and fuzzy logic. Stabilization is ensured via a sequence of forward and reverse path-tracking maneuvers.

Laser scanning system for inspecting large underwater hydroelectric structures

A novel robotic laser scanning system for the inspection of large underwater hydroelectric structures is proposed. This system has been developed at the Hydro Quebec Research Institute and consists of a laser camera mounted on a 2-D Cartesian manipulator. Mechanical, electronic, and software design aspects; overall operational modalities; and proof of concept results are presented. We evaluated the performances of the system in the course of laboratory experiments and inspection trials carried out under normal operating conditions at the site of three of Hydro Quebecs hydroelectric dams.

Microprocessor-based adaptive control of a crane system

This paper describes the design and implementation of a microprocessor-based adaptive controller for a crane system. A description of the experimental crane system is given and the mathematical model is presented. The adaptive controller is made of a state regulator bloc and a gain tuning module. The adjustment of the regulator gains as a function of the parameters value is made by means of a modified pole placement criterion. Performance improvments of the adaptive controller over an invariant controller, advantages and residual difficulties of sucha strategy are discussed on the basis of simulated experiments.

A Real-Time Computer Control Demonstrator for Use in a University Control Laboratory

An angular position servosystem made of a dc servomotor controlled by a TM990 microcomputer is described. The objective is to offer a control laboratory demonstrator for the study of a number of questions concerning computer control theory and practice. The control strategy uses state feedback and can be chosen to be either of the Kalman regulator type or of the bang-bang relay type; the parameters of these strategies such as gain, threshold, quantization levels, and sampling frequency can be selected via appropriate teletype commands. The evaluation of the state can be made in three different ways: a direct position and speed measurement, a direct measurement of the position followed by the computation of the derivative to obtain the speed, and the use of a Kalman-Bucy observer. The computer program is written in Basic.

Computed torque control of robots without joint velocity measurements

We present a robot motion controller that does not require velocity measurements. This controller combines an observer with the computed torque method. The stability of the resulting scheme is shown. The computational simplicity of the scheme is one of its advantages. Experimental results are presented to illustrate the performance of the scheme when measurement noise is present.

COOPERATIVE ROBOTIC SYSTEM USING DISTRIBUTED DECISION MECHANISMS WITH DELIBERATIVE CENTRAL SUPERVISOR

Cooperative multi-robot systems with distributed decision mechanisms and distributed sensing may be the source of decisional conflicts which can lead to severe performance deterioration. A deliberative central supervisor is a simple approach to correct any incoherent decisions in the system. Given an application, the supervisor can be an autonomous software agent or a human-machine interface. Using Hierarchical Decision Machines (HDM) as distributed decision mechanisms, the decision supervision can use simple matrix representations of decisional data. The resulting architecture has been tested on a fully autonomous team of soccer-playing robots and results indicate that it is well adapted for, but not restricted to, the specific needs of autonomous multi-robot systems with real-time distributed sensing and decision taking.