Force Sensor by Driving Hydraulic Cylinders: Identification of Inertial Parameters and Tests

Force feedback sensors are useful for the planning of robotic digging trajectories. In particular, when combined with force-control algorithms it becomes possible to sense buried objects and to determine the weight of excavated materials. The proposed force sensor system makes use of hydraulic cylinder pressure and thereby measures machine force indirectly. Successful implementation of such an approach will eliminate the need for expensive, direct-force sensors. Measurements of pressures in candidate cylinders were compared with laboratory-measured stroke and force. To measure force in every position and during the motion of a backhoe, kinematic, static and dynamic inertial parameters of the bucket, arm and other links have to be considered. From these data a friction model of the hydraulic cylinders can be developed. The present work involves the determination of these friction parameters for an excavator arm using position measures of the bucket and boom, cylinder pressures and the attitude of the excavator boom. Combined, these represent the “dynamic tare” of system. The work includes a practical approach to filtering regression matrix to do not measure accelerations. The methods allows one to carry out inertial parameters for a full machine, in order to verified design and drawning of costruction machine or to use as input for simulation of machine dynamics.