A pilot study of the reliability of the dynamic mode of one BTE Work Simulator

This paper presents the results of a study of the reliability of the manual dynamic mode of one BTE Work Simulator. The study was part of an effort to develop a simple method of calibrating the BTE Work Simulator as an evaluation instrument. Weights attached to a 12-in nylon cylinder rotated the shaft of the exercise head against resistance generated by the Work Simulator. A timing device recorded drop times for one complete revolution of the nylon cylinder. The timing device consisted of a digital clock, a photo detector circuit, and a switching circuit. The photo detector recorded one revolution of the cylinder, and the switching circuit started and stopped the clock. Drop times were recorded as fixed weights attached to the nylon cylinder were allowed to drop. The test was repeated a number of times at each combination of weight and exercise level. A minimum of 40 tests were recorded with 4.96-, 10-, 15-, 25-, 30-, and 40-lb weights. This provided accurate measurement of the performance of the Work Simulator in the dynamic mode. Fluctuation in resistance caused drop times for any given weight to vary from -47% to +183.7% from the mean. In some cases the resistance fluctuation was sufficient to either prevent the weight from dropping or stop the weight before the cylinder had rotated one revolution. Resistance variation in the dynamic mode of the BTE Work Simulator was found to produce inconsistent performance. Testing that includes other Work Simulators is in progress.