This paper discusses a haptic control strategy that can switch between position and rate control on the fly. When manipulating a remote device through teleoperation it is often desirable to complete tasks in position mode. This is because the slave is mimicking the motion of the master device (i.e. the human operator). Pure position control breaks down if the slave is a non holonomic device such as a forklift truck, earth moving vehicle or a skid-steer loader and the master has a holonomic robot with a finite workspace. In order to drive around, the forward motion must be controlled in rate mode when the device is move over long distances. Horizontal motion of the vehicle is also used to manipulate the end effector. Since tasks done by end effector are often done in a small region it is desirable to be able to switch into position mode in order to complete tasks with the end effector. Experimental results are presented using a PHANTOM as the haptic display and a Hydraulically Actuate Lifter (HAL) as a remote manipulator. These results show how a position/rate controller would behave in unconstrained motion, in the presence of virtual constraints and while picking up a load with the end effector.

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