Stewart Platform Simulator

Motivated by an interest in improving the operator interface of heavy hydraulic machines used in the forest industry, such as excavators, log-loaders and feller-bunchers, the UBC motion simulator was developed for research in (i) training of heavy equipment operators for hazardous jobs, (ii) control and human-factors studies for teleoperation from movable bases, and (iii) studies in virtual environments.

Picture Instead of taking the conventional approach of duplicating the machine cab environment by placing a heavy replica on a large hydraulic motion platform, as done in flight simulators and other heavy equipment simulators, this simulator carries only the operator sitting in a chair. The ``in cab'' feel will be provided by using computer or remote-camera generated stereo video images in a display helmet, computer generated motion cues and sound effects.
An inverted, ceiling-mounted Stewart platform design enables the use of narrower hydraulic cylinders than required with floor-mounted designs, and significantly reduces hydraulic flow requirements and hence the cost.

The UBC Stewart platform simulator uses six 1.5 inch bore, 54 inch stroke hydraulic actuators each controlled in a three-way configuration. The jacks are anchored by roller-bearing U-joints in 120 degree symmetric configurations on the base and platform. Each cylinder is capable of forces in excess of 4000 N at a 1 m/s speed, and over 8000 N at zero rod speed. Based on the cylinder performance, the predicted platform acceleration with a payload of 250 Kg is of +- 1g, +- 400 degrees/s/s, at speeds exceeding +-1 m/s and +- 30 degrees/s.

Design details can be found in [Salcudean et al '94] and [Peter Drexel's M.A.Sc. thesis]. [Research support provided by NSERC, IRIS/PRECARN and the BC ASI]