Abstract/Summary

A one degree of freedom experimental test bed is used to investigate the effects of elastic vibration in haptic devices. Strong angular vibration occurs at the motor rotor due to elastic deformation in the shaft. These vibrations occur due to large discontinuities in the virtual environment such as stiff contact which is common in haptics. Also looked at was the effect of these vibrations on stability and control. It was found that the vibrations may negatively affect the stability of the haptic device by introducing large measurement errors to the controller. The experiments investigated using different types of damping in controller feedback. Adding damping to the system whilst these elastic vibrations are present can successfully damp the system, but also tend to increase the magnitude of vibrations sometimes resulting in greater instability. Finally, a second non co-located encoder was used to try to eliminate measurement error from the system due to vibration. It was found that by simply placing the encoder closer to the link where the angle is being measured, error due to rotational flex in the shaft is eliminated. This yielded the greatest improvement in controller performance, nearly eliminating the presence of the vibrations and their effects.