Bertrand Tondu

A Seven-degrees-of-freedom Robot-arm Driven by Pneumatic Artificial Muscles for Humanoid Robots

Braided pneumatic artificial muscles, and in particular the better known type with a double helical braid usually called the McKibben muscle, seem to be at present the best means for motorizing robot-arms with artificial muscles. Their ability to develop high maximum force associated with lightness and a compact cylindrical shape, as well as their analogical behavior with natural skeletal muscle were very well emphasized in the 1980s by the development of the Bridgestone “soft robot” actuated by “rubbertuators”. Recent publications have presented ways for modeling McKibben artificial muscle as well as controlling its highly non-linear dynamic behavior. However, fewer studies have concentrated on analyzing the integration of artificial muscles with robot-arm architectures since the first Bridgestone prototypes were designed. In this paper we present the design of a 7R anthropomorphic robot-arm entirely actuated by antagonistic McKibben artificial muscle pairs. The validation of the robot-arm architecture was performed in a teleoperation mode.

The McKibben muscle and its use in actuating robot‐arms showing similarities with human arm behaviour

Describes the McKibben muscle and its major properties. Outlines the analogy between this artificial muscle and the skeletal muscle. Describes the actuator composed of two McKibben muscles set into antagonism based on the model of the biceps‐triceps system, and explains its natural compliance in analogy with our joint litheness. Reports some control experiments developed on a two d.o.f. robot actuated by McKibben muscles which emphasize the ability of these robot‐arms to move in contact with their environment as well as moving loads of high ratio to the robot’s own weight. Also outlines control difficulties and accuracy limitations and discusses applications.

TER: A System for Robotic Tele-echography

The quality of ultrasound based diagnosis highly depends on the operators skills. Some healthcare centres may not have the required medical experts on hand when needed and therefore may not benefit from highly specialized ultrasound examinations. The aim of this project is to provide a reliable solution in order to perform expert ultrasound examinations in distant geographical areas and for the largest population possible. TER is a telerobotic system designed and developed by a French consortium composed of universities, hospitals and industrial companies. One originality of TER is the development of a compliant slave robot actuated by muscles. This slave robot is teleoperated by an expert clinician who remotely performs the exam. In this paper, we present the architecture of TER and describe its components.

Experiments with the TER Tele-echography Robot

This paper presents a master-slave system applied to the remote diagnosis from echographic data. The motion of the master manipulator is remotely controlled by a physician and reproduced by a slave robot carrying the echographic probe. The contact force between the probe and the patient is fed back to operator allowing him to have a haptic virtual environment. The innovation of this haptic control is to preserve medical expert propioception and gesture feelings, which are necessary to synchronize the ultrasound images with the motion made by the medical doctor. The slave robot is a cable-driven manipulator using pneumatic artificial muscle actuators to control the motion of the ultrasound probe. In this paper we present the architecture and the performances of the slave robot and the first experiments of the master-slave remote echography system for examinations of pregnant women.

Modelling of the shoulder complex and application the design of upper extremities for humanoid robots

The classic industrial robot-arm does not need a shoulder in the anatomical sense: it is merely placed on a rotating trunk. The recent development of humanoid robots in which two arms must move laterally to a frame-trunk raises the question of integrating anthropomorphic shoulders. A rigorous analysis of the mobility of the so-called human shoulder complex is necessary in the design of robot shoulders. A kinematic model of the shoulder complex is discussed and its mobility derived. The consideration of a simple clavicle-based equivalent kinematic model has lead to highlight a serial nine d.o.f. anthropomorphic robot structure. By considering a fundamental kinematic model of a robot-arm including a clavicle-like link, it is shown how the elbow singularity can be limited to a restrictive zone of the reachable volume

Adaptive fuzzy nonsingular terminal sliding mode controller for robot manipulator actuated by pneumatic artificial muscles

In this paper, we deal with the robust control of robot manipulator actuated by pneumatic artificial muscles. The control consists on the combination of the nonsingular terminal sliding mode which is based on the time delay estimation method and an adaptive fuzzy logic system based on the gradient descends algorithm. First, the nonsingular terminal sliding mode control approach was presented and the stability of the system in closed loop was analyzed using Lyapunov stability theorem. Second, adaptive fuzzy logic scheme is proposed for reducing the chattering effect. Third, in order to proof the efficiency and the superiority of the proposed approach, this last is experimented and compared to nonsingular terminal sliding mode controller and to fuzzy nonsingular terminal sliding mode controller under 2-DOF robot manipulator actuated by pneumatic artificial muscles.

Robust stabilization and tracking for robotic manipulators with artificial muscles

The robustness of a dynamical sliding mode control strategy with respect to unmatched perturbation inputs and modelling errors is examined for robotic manipulators equipped with an arrangement of antagonistic artificial muscles, acting as actuators. Differential flatness, which in the case of single-input manipulators coincides with exact linearizability of the system, is exploited to obtain a discontinuous feedback control strategy. The approach naturally allows for the introduction of a first order servovalve-artificial muscle actuator model for sliding mode controller design purposes.

Comparison of two significant development methods applied to the design of real-time robot controllers

This paper presents the principal functionalities of robot-manipulator controllers and a comparative study of two development methods for real-time systems applied to this controller. The selected techniques are SART and the unified method associated to UML, because they represent two classical types of modelling techniques: structured design with functional decomposition and object-oriented methodology. We analyse seven design issues associated to the robot controller development process and its utilisation comparing these two methods.

Practical design of real time VSS applied for flexibal robot

In robust control, variable structure system (VSS) theory is appreciated to design control under heavy uncertainties. In this paper authors present controlling a flexible robot arm driven by pneumatic artificial rubber muscles (Parms) with direct transmission. The sliding modes control (SMC) is a special case of VSS. Usually in the SMC, the equivalent control is associated with high frequency control to reduce chattering. Amongst the latter, those applied are the twisting and the super twisting algorithms, which belong to the 2-high order sliding control set. In this paper we focus on the relevance of such an equivalent control based on truly uncertain model. Also It will be shown the effect of a noised sensor signal on the control performances, the use of an additional discontinuous term, which increases performance and stability. Experimental results are presented and discussed.

Biologically inspired sensory motor control of a 2-link robotic arm actuated by McKibben muscles

This study focuses on biomimetic sensory motor control of a robotic arm. We have developed a command circuit that was mathematically deduced from physical and mathematical constraints describing the function of cerebellar pathways. The control circuit contains an internal predictive model of the direct biomechanical function of the limb placed in a closed loop, so that the circuit computes an approximate inverse function. The structure of the model resembles the anatomic connectivity of the cerebellar pathways. In this paper, we present an application of this model to the control of a 2-link robotic arm actuated by four single-joint McKibben muscles and report the results obtained by simulation and real-time learning of 2 degrees of freedom pointing movements.