A means of automatically reproducing operator demonstrated excavation trajectories has been developed
for the automation of repetitive digging tasks and the teleoperation of remote machines. The dynamic adjustment of backhoe end-effector impedance, according to a variable impedance-control strategy, has been proposed for this purpose. This strategy matches machine end-point and environment impedances by means of a new, generalised duality principle which enables simultaneous position and force control over varying environment characteristics, by observing a specified compromise between position and force trajectory errors.
A virtual excavation environment has been designed and implemented to provide an inexpensive, safe, flexible, yet realistic platform for the development and evaluation of such automation and control strategies. The simulator comprises a mechanical impedance model of the excavator manipulator,
a model for the synthesis of bucket-ground interaction forces, as well as graphical and haptic interfaces for both visual and force feedback. Experimental results show that task demonstration and playback within a virtual excavation environment
results in appropriate trajectory tracking throughout a digging motion which encounters
environment impedances ranging from free motion to hard contact.Applied Science, Faculty ofElectrical and Computer Engineering, Department ofGraduat
