AUTOMATIC-CONTROL OF UNDERGROUND VEHICLES AT HIGH-SPEED

Automatic driving al high speed of an underground truck was tested al Brunswick mine in September 1995. Modifications to the truck included: a remote interface to control actuators, front and back video cameras to follow a roof mounted optical guide and proportional hydraulic con trols on the steering. The mathematical model of the hydraulic system was adjusted using least square regression. The steering data, used in calculating the regression parameters, were acquired from the moving truck. The automatic steering control used three measured variables. l ateral deviation, angular deviation and steering angle. lateral deviat ions are obtained using the cameras, which are in continuous view of t he guide, while steering angles are acquired from an extensiometer pla ced at the articulation point of the vehicle. Gain scheduling was used to compensate for vehicle speed and available hydraulic flow Non-line ar characteristics of the modeled hydraulic system were offset using o pen loop compensation. Speeds up to 23 km/h in forward direction and 1 3 km/h in reverse were achieved during continuous testing along one of the mine's production drifts. Proportional steering was essential in achieving high speeds, as it enabled more precise positioning of the v ehicle's steering direction while reducing the abuses on cylinder and cylinder pins via diminished oscillations about the optical guide at h igh speeds.