METHOD OF CONTROLLING A MOTOR DRIVEN SYSTEM, APPARATUS FOR CONTROLLING A MOTOR DRIVEN SYSTEM AND A MOTOR DRIVEN SYSTEM CONTROLLED IN ACCORDANCE WITH THE DISCLOSED METHOD

摘要

Actuators are used to move a variety of objects to desired positions. It is generally desirable that they can do this quickly without exhibiting overshoot or ringing. Some actuators are required to respond very quickly and examples of these are voice coil drivers used to move lenses in autofocus cameras provided in everyday devices such as smart phones and tablets. A rapid two step controller scheme had already been disclosed by Analog Devices Inc. Whilst the scheme works well, it can only be used reliably if the resonant frequency of the actuator is known to within 2 or 3%. The inventors have discovered that the resonant frequency of an actuator unexpectedly changes as a function of position. This disclosure provides ways of modifying the control scheme to cope with changes in resonant frequency.

主权项

1. A method of driving a motor driven mechanical system from a first position to a second position, the method comprising:
i) calculating a change in a drive signal to move the mechanical system from the first position to the second position; ii) dividing the change in the drive signal into a plurality of drive steps so as to form at least a first intermediate drive signal value and a final drive signal value; iii) applying the first intermediate drive signal value for a time tu, and then applying the final drive signal value; wherein the time tu is a variable.