Abstract
Model-mediated teleoperation (MMT) employs an environment model at the master side to compute feedback output to the master at a faster rate. This approach improves system stability in the presence of time delay. MMT, however, does not generally perform well if the employed model is not accurate. The model mismatch is unavoidable when the environment is unknown in advance or varies. This paper proposes MMT employing an adaptive model. The proposed method adaptively moves the reference point of the employed model, whereas the previous MMTs used reference points fixed to the surface of objects in the environment. This can make system stability independent of the time delay. Experiments show that the proposed method improves stability compared to the previous MMTs when there are model mismatches. User studies are conducted to compare the operator’s performance in two tasks, control of force exerted to objects in the environment, and discrimination of object stiffness. The result shows that the error in the forces applied to objects in the environment significantly decreases in the proposed method. Errors in forces rendered to the master are also improved by at least 20.2%. The experiment result also shows that subjects can discriminate up to 40.9% smaller differences in the stiffness than the previous MMT under the same time delay.
Highlights
Bilateral teleoperation with haptic feedback has often been investigated for two practical tasks
This paper proposes an Model-mediated teleoperation (MMT) method which can solve the stability problem without adjusting the stiffness rendered to the operator, in contrast to the previous MMTs that adjust the rendered stiffness to stabilize the system
Stability of the master-slave control system becomes independent of the time delay between the t d =1ms 60 t d =100ms 60
Summary
Bilateral teleoperation with haptic feedback has often been investigated for two practical tasks. The first is to control forces applied to objects. Robotic surgery often requires knot-tying after suturing [1]. Too much pulling force on the suturing string can break the fine suture or damage the soft tissue. The knot cannot be held firmly if the pulling force is too weak. Haptic feedback can be used for handling fragile objects such as soft tissues [2] and explosive ordnances [3]. A surgeon can distinguish normal healthy tissues from indurated tissues through haptic sensation [4]. The surgeon can estimate boundaries of the abnormal tissue. This paper aims to improve performance of these two teleoperation tasks
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