In recent years, there has been an increasing usage of joystick as a cursor control device. Specifically in an ultrasonic diagnosis machine, joystick is a major control device in an ultrasonic image processing.
The relation between control device movement and controlled element movement has been recognized as a factor in the design of operator machine interfaces. It can be defined as control display gain or control display ratio, one being the reciprocal of the other.
This study proposes the optimal ratio of joystick which balances the advantages of a relatively high gain in reducing the time to finish the image processing task against the advantages of a relatively low gain in making the correct movements on to target.
