Development of a simulator for a powered wheelchair and practical use for a person with physical and mental disabilities.

Independent mobility is an important factor in determining the quality of life. The powered wheelchair is a significant device in ensuring independent mobility for persons with severe disabilities. The adaptation of wheelchairs to persons with severe disabilities, however, is very difficult and takes a long time because many trials are needed. The purpose of this study is to support this complex situation.This paper describes development and practical use of a simulator for a powered wheelchair. The simulator has two computer screens and a moving platform. The screens show computer graphics of a virtual driving course, which includes traffic signs, a railroad crossing, a pathway with a curb from the roadway, a roadway with a cross slope, rough surfaces with bricks, slopes, and a cross slope. Some pedestrians and some bicycles come along on some of the path- and roadways. The platform is connected to six linear servo actuators that work by electric power. The actuators generate accelerations and decelerations similar to those of a real powered wheelchair.This system has a mathematical model of a powered wheelchair in the computer. Since it is driven by torque of the right and left drive wheels, it gets slower on an uphill slope and faster on a downhill slope. The model also turns downhill on a cross slope.Fifteen subjects, including two powered wheelchair users, drove the simulator. Results of this evaluation revealed that drivers of the simulator had virtual experiences that were quite similar in many ways to driving a powered wheelchair. The subjects, however, felt it more difficult to operate the simulator than to drive a real powered wheelchair. This was caused by the absence of a side view. Another problem was motion sickness, which was experienced by about half of the subjects. Caution about motion sickness is needed during the first trial of this simulator.A person with physical and mental disabilities tried the simulator in order to learn operation of a powered wheelchair. He lacked comprehension, concentration, and motivation. The first trial, of operating only one switch for driving the simulator, showed that he could understand the system and concentrate his attention on the operation. The next trial, requiring operation of two switches for driving, showed that he could not stop when a risk of collision arose. At this stage, we didn’t think he could drive the powered wheelchair. The last trial, controlling direction using head movement, however, showed he turned the wheelchair along the line on the road. This was a surprising result. These evaluations revealed that he could drive a powered wheelchair if it compensated for safety by itself.The simulator is effective in determining if a person with very severe disability can drive a powered wheelchair. This attempt will extend independent mobility of persons who have been regarded as unable to drive powered wheelchairs.