Apparatus for controlling the movement of a movable element.

摘要

Apparatus is disclosed for controlling the movement of a movable element (20 or 22) between an initial starting position and a final stopping position. The apparatus comprises drive means (34 or 36) coupled to the movable element and responsive to motor drive signals for moving the movable element (20 or 22) along a predefined path between the starting and stopping positions. The apparatus generates an actual velocity signal indicative of the actual speed of movement of the movable element, a position signal indicative of the distance remaining to travel by the movable element toward the desired stopping position and first and second command velocity signals respectvely indicative of the minimum and maximum desired velocity levels for such particular distance remaining to travel. A controller (26) is responsive to the position signal for comparing the actual velocity signal with each of the first and second command velocity signals when the value of the position signal indicates the movable element has greater than a predetermined distance to travel, and for issuing the motor drive signals in response to such comparison for application to the drive means (34 or 36) to cause (a) the acceleration of the movable element (20 or 22) by the drive means when the comparison indicates the actual velocity of the movable element is less than the minimum desired velocity, (b) the coasting of the movable element when the comparison indicates the actual velocity of the movable element is more than the minimum desired velocity and less than the maximum desired velocity, and (c) the deceleration of the movable element by the drive means when the comparison indicates the actual velocity of the movable element exceeds the maximum desired velocity.