pab Ltd study drive principles on steep terrain (ATV)

• extremely low centre-of-gravity
• very tight turning circle
• very precise low speed control
• maximal traction
• complete software drive, joystick input ("drive by wire")
• designed for a maximum inclination of terrain: 45°
• modular chassis, width 1.4m , length 2.5m, wheelbase 1.2m

• aim of project: gather experience in control- and drive-algorithms for 4x4 vehicle in steep terrain with full traction control
• work area: grass surface with an inclination between 25° and 45°
• optimise tilt-safety around any axis by design
• maximise traction while leaving grass surface mostly intact
• all-digital differential control

• distributed four-wheel drive with active speed control, CAN bus controlled for maximum traction
• diesel engine made by Hatz with custom oil sump for continuous operation up to 45° tilt
• computer adjustable, variable displacement axial piston pump made by Bosch for high efficiency
• hydraulic driven radial piston wheel motors for efficiency and fine control at very low RPM
• steering angle ± 45° , twist angle ± 20° for maneuvers in tight space
• Linux based control for reliability
• second, redundant break system (dead-man-switch)
• optional remote control (although much less fun)

• wheel-based preferred over track-based
• steering concept: articulated-frame steering preferred
• test of geometric parameters by simulation and physical models
  (version dubbed k5 since it had been the 5th version during preliminary planning)
• hydraulic preferred over electric drives (well- that is open to discussion now)
• hydraulic motors with high efficiency at lowest RPM
• electronics for low speed control of hydraulic flow
• including extra set-up to test low-speed, variable load control of hydraulic motors
• in-service use of vehicle to gain practical experience for drive techniques on inclined slopes
• identify key optimisations for next generation

ATV development at pab advanced technologies Ltd
Peter Apian-Bennewitz, email: atv@pab.eu