Apparatus and method for fine positioning a vehicle at a storage bin in an automatic storage and retrieval system

摘要

An automatic storage and retrieval system including a storage bin, having a mechanism for positioning a vehicle at the storage bin including a rough positioning mechanism with an encoder having a rotatable member which rotates through an arc less than a complete revolution in response to movement of the vehicle and generates a signal with a different value at each of various member positions which correspond to respective vehicle rough position zones. A control device receives the signal and selectively causes the vehicle to move to a rough position zone at the storage bin. A fine positioning mechanism repositions the vehicle within a particular position zone after rough positioning and utilizes a light source and photoelectric sensor mounted on the vehicle for detecting a target mounted in a fixed relation with respect to the storage bin. The control mechanism receives an electrical signal generated by the photoelectric sensor and causes the vehicle to stop at the fine position location at the storage bin. A high-low positioning device selectively lowers and raises a carriage including a retrieval apparatus such as a fork assembly within the bin. A method is provided to utilize the automatic storage and retrieval system including rough and fine positioning of a vehicle relative to a storage bin and high-low positioning within the bin.