Abstract
This paper discusses the influence of spatial characteristics of objects on a surface following control system equipped with an ultrasonic orientation sensor, and proposes a method to evaluate the performances of the control system by spatial frequency response.
The sensor measures the orientation by the phase difference of reflected echoes and is applied to the control system to maintain the hand orientation perpendicular to the objective surface.
The measuring algorithm of the sensor is based on the mirror property of sound reflection from a plate with an infinite area. However, actual object for surface following task has uneven surface. The unevenness causes significant errors on the measured orientation. Consequently, the control system using the sensor is also influenced by surface characteristics of the objects.
The characteristics are expressed by spatial frequency response. The method using the frequency response is very usefull for evaluation of the performances of the control system, such as the ability to follow the curved surface and the ability to reduce the influence of small irregularities on the surface.
