POWER WHEELCHAIR RANGE TESTING AND ENERGY-CONSUMPTION DURING FATIGUE TESTING

The range of a power wheelchair depends on many factors including: bat tery type, battery state, wheelchair/rider weight, terrain, the effici ency of the drive train, and driving behavior. The purpose of this stu dy was to evaluate the feasibility of three methods of estimating powe r wheelchair range. Another significant purpose was to compare the cur rent draw on pavement to current draw on an International Standards Or ganization (ISO) Double Drum tester at one m/sec. Tests were performed on seven different power wheelchairs unloaded, and loaded with an ISO 100 kg test dummy. Each chair was configured according to the manufac turer's specifications, and tires were properly inflated. Experienced test technicians were used for the tennis court tests, and treadmill t ests. An ISO 100 kg test dummy was used for the ISO Double Drum test. Energy consumption was measured over a distance of 1500 m for each of the three test conditions. The rolling surface was level in all cases. Repeated measure analysis of variance (ANOVA) revealed a significant difference (p=0.0001) between the predicted range at maximum speed for the three tests. Post hoc analysis demonstrated a significant differe nce (p<0.01) in estimated range at maximum speed between the Double Dr um test and the treadmill test, as well as between the Double Drum tes t and the tennis court test. Our results indicate no significant diffe rence (p>0.05) between the predicted range at maximal speed between th e treadmill and tennis court tests. A simple relationship does not exi st between the results of range testing with the Double Drum tester an d the tennis court. An alternative would be to permit the use of a tre admill for range testing as simple relationships between all pertinent treadmill and tennis court range data were found. For the Double Drum tester used, the current demand is higher than under normal usage. Th is presents a problem as current is related to load torque in a power wheelchair. Hence, the Double Drum tester friction must be reduced. Th e predicted range for the tennis court test at maximum speed ranges fr om a low of 23.6 km to a high of 57.7 km. The range of the power wheel chair can be improved by the use of wet lead acid batteries in place o f gel lead acid batteries.