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Accueil > Evénements > Archive des séminaires Ampère > Séminaires Ampère 2010

09/12/2010 : Séminaire du Département MIS : Minh-Quyen

par Laurent Krähenbühl - publié le

Le 09/12 à 15h à l’ INSA St Exupéry : M.Minh-Quyen, doctorant (2008-2011), donnera un séminaire intitulé :

Development of haptic interfaces for teleoperation system using pneumatic actuators

Résumé :

One of the thesis objectives is to investigate the possibility to use electro-pneumatic actuators in a teleoperation haptic device. Pneumatic systems have recently become more popular due to their advantages of high mass-to-force ratio, inert to magnetic field, cleanliness, easiness in compliance control and recent breakthroughs in valve technology. Instead of using classical proportional servovalves for the mass flow rate control, fast-switching on/off valves were chosen due to their low cost and small size. The purpose is to show that a good transparency in bilateral control can be obtained with these cheap components. The traditional method for controlling systems with solenoid valves is to use Pulse Width Modulation (PWM) to control the output mass flow rate of a solenoid valve. A main disadvantages of such a control is the chattering phenomenon due to the high frequency switching of the valve in steady state. The chattering problems can reduce drastically the valve’s lifetime and generate noises which may be disturbing for some applications. To overcome the PWM’s disadvantages and to efficiently control the switching on/off valves, we present a new control method, which is based on hybrid control theory. For this strategy, a control vector, depending on the number of possible configurations for the solenoid valves, is defined. The hybrid control has been successfully implemented in experiments on a one-degree-of-freedom master/slave telemanipulator. In experiments, it was observed that with the four-channel bilateral teleoperation control architecture employing this hybrid control algorithms, satisfactory force and position tracking between the master and the slave is obtained under both freemotion and contact-motion conditions.

The results are encouraging for future applications of hybrid control to multi-DOF, pneumatically-driven teleoperation systems. While the proposed hybrid control is based on a one-step-ahead prediction of pressures in the pneumatic chambers, an aspect of future work is to extend the control law to involve a multi-step prediction in order to improve the tracking performance. Finally, some nonlinear control strategies for pneumatic actuators with solenoid valves were developed but have not been implemented in teleoperation systems yet. This represents an alternative research path to be investigated.