12-04-2012, 03:54 PM
DEVELOPMENT OF A HYDRAULIC MASTER-SLAVE SYSTEM FOR TELEROBOTICS
[attachment=20011]
INTRODUCTION
In a teleoperated manipulation system, the operator needs not only a visual representation but
also a haptic representation of a system existing in a remote place. Those devices of haptic
display, at present, have problems, such as insufficiencies in the display functions and complications
in their constitutions.
A NEW DRIVING METHOD OF HYDRAULIC SERVO-SYSTEM BY
MEANS OF A FORCE SENSOR
In order to produce a haptic display applicable to hydraulic servo-systems, we must solve a
problem called back-drivability, in which an actuator in a hydraulic servo-system cannot be
operated freely by means of a manual force. The problem is caused mainly by the operating
principle of the servo-valve. Due to this problem, the operator has such difficulty that he is
unable to drive the system manually, by operating, for example, a cylinder or a servo-valve.
Hydraulic System with Haptic Display
Dealing with the system in Fig. 2, we investigate experimentally the function of the haptic
display. In this experiment, a load-force for feeding back to the operator needs to be produced
in the system. For this purpose, the system in Fig. 2 was rearranged into the one shown in
Fig. 3. In the new system, a spring of stiffness k was set to the cylinder for simulating a loadforce.
This spring is not actual but virtual, provided by means of a computer program. In the
equilibrium state of the system, the mass-load is located at a distance of 10 mm from the
spring-end.
Master-slave Hydraulic System with Haptic Display
To realize a teleoperated manipulation system as shown in Fig. 1, it is necessary to constitute
a master-slave system, in which the master and the slave correspond, respectively, to a haptic
display and an actuating manipulator. In this section we therefore discuss a master-slave
hydraulic system equipped with the new haptic display proposed.
CONCLUSIONS
In the first place, for the use of hydraulic servo-systems, we proposed in this study a hapticdisplay
device. The function of the haptic display in this device is generated in terms of a
control algorithm through a force sensor. The proposed device was applied to a one-DOF
hydraulic system and tested to confirm its applicability. It was verified in the experiment that
the operator of the system was able to drive a piston manually with ease. Furthermore, the
operator was able to feel sensitively the reaction forces caused by virtual load-springs.
[attachment=20011]
INTRODUCTION
In a teleoperated manipulation system, the operator needs not only a visual representation but
also a haptic representation of a system existing in a remote place. Those devices of haptic
display, at present, have problems, such as insufficiencies in the display functions and complications
in their constitutions.
A NEW DRIVING METHOD OF HYDRAULIC SERVO-SYSTEM BY
MEANS OF A FORCE SENSOR
In order to produce a haptic display applicable to hydraulic servo-systems, we must solve a
problem called back-drivability, in which an actuator in a hydraulic servo-system cannot be
operated freely by means of a manual force. The problem is caused mainly by the operating
principle of the servo-valve. Due to this problem, the operator has such difficulty that he is
unable to drive the system manually, by operating, for example, a cylinder or a servo-valve.
Hydraulic System with Haptic Display
Dealing with the system in Fig. 2, we investigate experimentally the function of the haptic
display. In this experiment, a load-force for feeding back to the operator needs to be produced
in the system. For this purpose, the system in Fig. 2 was rearranged into the one shown in
Fig. 3. In the new system, a spring of stiffness k was set to the cylinder for simulating a loadforce.
This spring is not actual but virtual, provided by means of a computer program. In the
equilibrium state of the system, the mass-load is located at a distance of 10 mm from the
spring-end.
Master-slave Hydraulic System with Haptic Display
To realize a teleoperated manipulation system as shown in Fig. 1, it is necessary to constitute
a master-slave system, in which the master and the slave correspond, respectively, to a haptic
display and an actuating manipulator. In this section we therefore discuss a master-slave
hydraulic system equipped with the new haptic display proposed.
CONCLUSIONS
In the first place, for the use of hydraulic servo-systems, we proposed in this study a hapticdisplay
device. The function of the haptic display in this device is generated in terms of a
control algorithm through a force sensor. The proposed device was applied to a one-DOF
hydraulic system and tested to confirm its applicability. It was verified in the experiment that
the operator of the system was able to drive a piston manually with ease. Furthermore, the
operator was able to feel sensitively the reaction forces caused by virtual load-springs.