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

• US 4,428,708 A
• Filed: 12/31/1980
• Issued: 01/31/1984
• Est. Priority Date: 12/31/1980
• Status: Expired due to Fees

• Current Assignee: Mid-West Conveyor Company, Inc.
• Original Assignee: Mid-West Conveyor Company, Inc.
• Inventors: Burt, Harold S.
• Primary Examiner(s): Reeves, Robert B.
• Assistant Examiner(s): WACYRA, EDWARD MICHAEL
• Application Number:
  US06/221,792
• Time in Patent Office: 1,126 Days
• Field of Search: 414/273, 414/275, 414/277, 414/279, 414/281, 414/282, 364/478, 364/444, 318/592, 318/594, 318/601, 318/602, 340/680, 340/686
• US Class Current: 414/275
• CPC Class Codes: B65G 1/0421 with control for stacker crane operations

Abstract

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.

Claims

1. A system for positioning a carriage movably mounted on a vehicle at a predetermined storage bin in one of a bin high position and a bin low position, which comprises:

(a) energy source means and energy sensing means mounted on one of said carriage and said vehicle;

(b) a discrete energy reflective bin high target mounted on the other of said carriage and said vehicle;

(c) a discrete energy reflective bin low target mounted on said other of said carriage and said vehicle;

(d) a discrete energy reflective bin safe target mounted on said other of said carriage and said vehicle;

(e) said carriage having a laterally extendable fork;

(f) said energy sensing means being adapted to receive energy from said energy source means reflected by said targets;

(g) control means operably connected to said energy sensing means for causing said carriage to move to one of said bin high and said bin low positions and for stopping said carriage in one of said bin high and said bin low positions at said predetermined storage bin upon said energy sensing means being actuated by energy reflected from a respective one of said bin high and said bin low targets;

(h) said control means preventing vertical movement of said carriage with said fork thereof laterally extended except when said energy sensing means receives energy from said energy source reflected from said bin safe target.

2. The system according to claim 1 which includes:

(a) said bin safe target having an upper portion and a lower portion;

(b) said bin high target being mounted adjacent said bin safe target upper portion; and

(c) said bin low target being mounted adjacent said bin safe target lower portion.

3. The system according to claim 1 which includes:

(a) said carriage positioning system comprising a fine positioning system; and

(b) a carriage rough positioning system including distance measuring means for determining a distance traveled by said carriage from a start address to one of a bin high rough position zone including said bin high position and a bin low rough position zone including said bin low position.

4. The system according to claim 3 which includes:

(a) said distance measuring means comprising an encoder operably connected to said carriage and to said control means.

5. A system for fine positioning a carriage movably mounted on a vehicle at a predetermined one of a plurality of storage bins in one of a bin high position and a bin low position, which comprises:

(a) a light source mounted on said carriage;

(b) a bin high photoelectric sensor mounted on said carriage;

(c) a bin low photoelectric sensor mounted on said carriage;

(d) a bin safe photoelectric sensor mounted on said carriage;

(e) a plurality of discrete light reflective bin high targets mounted on said vehicle adjacent a path of movement of said bin high photoelectric sensor;

(f) a plurality of discrete light reflective bin low targets mounted on said vehicle adjacent a path of movement of said bin low photoelectric sensor;

(g) a plurality of discrete light reflective bin safe targets mounted on said vehicle adjacent a path of movement of said bin safe photoelectric sensor;

(h) said carriage having a laterally extendable fork; and

(i) control means operably connected to said photoelectric sensors for causing said carriage to move to one of said bin high and said bin low positions and for stopping said carriage in one of said bin high and said bin low positions at said predetermined storage bin;

(j) said control means preventing vertical movement of said carriage with said fork thereof laterally extended except when said bin safe photoelectric sensor receives light reflected from one of said bin safe targets.

6. In an automated warehouse having a storage rack with a plurality of storage bins arranged in vertical columns and horizontal rows, a system for positioning a carriage vertically movably mounted on a horizontally movable vehicle at a predetermined storage bin in one of a bin high position and a bin low position, which comprises:

(a) a horizontal positioning system including;

(1) a light source mounted on said vehicle;

(2) a photoelectric sensor mounted on said vehicle; and

(3) a plurality of light reflective targets mounted adjacent a path of movement of said photoelectric sensor mounted on said vehicle;

(b) a vertical positioning system including;

(1) a light source mounted on said carriage;

(2) a bin high photoelectric sensor mounted on said carriage;

(3) a bin low photoelectric sensor mounted on said carriage;

(4) a bin safe photoelectric sensor mounted on said carriage;

(5) a plurality of discrete light reflective bin high targets mounted on said vehicle adjacent a path of movement of said bin high photoelectric sensor;

(6) a plurality of discrete light reflective bin low targets mounted on said vehicle adjacent a path of movement of said bin low photoelectric sensor; and

(7) a plurality of discrete light reflective bin safe targets mounted on said vehicle adjacent a path of movement of said bin safe photoelectric sensor;

(c) said carriage having a lateraly extendable fork; and

(d) control means operably connected to said photoelectric sensors for causing said vehicle to move to a horizontal position adjacent a respective column containing said predetermined storage bin and for causing said carriage to move to one of said bin high and said bin low positions at said predetermined storage bin;

(e) said control means preventing vertical movement of said carriage with said fork thereof laterally extended except when said bin safe photoelectric sensor receives light reflected from one of said bin safe targets.

7. A positioning method whereby a vehicle located at a start address is positioned at a fine position location within a rough position zone including a destination address, which comprises the steps of:

(a) generating a signal having a first non-ambiguous binary value corresponding to said start address;

(b) communicating said signal having said first value to control means for said vehicle;

(c) receiving in said control means a second nonambiguous binary value corresponding to said destination address;

(d) comparing in said control means said first and second values;

(e) expanding said second value to a range of nonambiguous binary values corresponding to said rough position zone;

(f) causing with said control means said vehicle to travel from said start address to said rough position zone;

(g) generating a signal having a value within said range;

(h) communicating said signal having said value within said range to said control means whereby said vehicle is designated as being located in said rough position zone;

(i) projecting energy from energy source means mounted on said vehicle;

(j) reflecting said energy with an energy reflective target when said vehicle is in said fine position location;

(k) sensing said reflected energy with energy sensing means mounted on said vehicle;

(l) generating with said energy sensing means a signal in response to sensing said reflected energy;

(m) communicating said signal from said energy sensing means to said control means; and

(n) causing with said control means said vehicle to stop at said fine position location.

8. A positioning method whereby a carriage located at a start address is positioned at a fine position location in one of a bin high rough position zone and a bin low rough position zone at a destination address, which comprises the steps of:

(a) generating a signal having a first non-ambiguous binary value corresponding to said start address;

(b) communicating said signal having said first value to control means for said carriage;

(c) receiving in said control means a second non-ambiguous binary value corresponding to said destination address;

(d) comparing in said control means said first and second values;

(e) determining if a load is present on said carriage;

(f) biasing said second value to a bin high non-ambiguous binary value corresponding to said bin high rough position zone if a load is present on said carriage;

(g) biasing said second value to a bin low non-ambiguous binary value corresponding to said bin low rough position zone if a load is not present on said carriage;

(h) causing with said control means said carriage to move to one of said bin high and said bin low rough position zones to which said biased second value corresponds;

(i) generating a signal having said biased second value;

(j) communicating said signal having said biased second value to said control means whereby said vehicle is designated as being located in said one of said bin high and said bin low rough position zones;

(k) projecting energy from energy source means mounted on said carriage;

(l) reflecting said energy when said carriage is in said fine position location;

(m) sensing said energy with energy sensing means mounted on said carriage;

(n) generating with said energy sensing means a signal in response to sensing said reflected energy;

(o) communicating said signal from said energy sensing means to said control means; and

(p) causing with said control means said carriage to stop at said fine position location.

9. A positioning method whereby a vehicle located at a horizontal start address is positioned at a horizontal fine position location within a horizontal rough position zone including a horizontal destination address and a carriage vertically movably mounted on the vehicle and located at a vertical start address is positioned at a vertical fine position location within one of a bin high rough position zone and a bin low rough position zone at a vertical destination address, which comprises the steps of:

(a) generating a signal having a first non-ambiguous binary value corresponding to said horizontal start address;

(b) communicating said signal having said first value to control means for said vehicle;

(c) receiving in said control means a second non-ambiguous binary value corresponding to said horizontal destination address;

(d) comparing in said control means said first and second values;

(e) expanding said second value to a range of non-ambiguous binary values corresponding to said horizontal rough position zone;

(f) causing with said control means said vehicle to travel from said horizontal start address to said horizontal rough position zone;

(g) generating a signal having a value within said range;

(h) communicating said signal having said value within said range to said control means whereby said vehicle is designated as being located in said horizontal rough position zone;

(i) projecting energy from energy source means mounted on said vehicle;

(j) reflecting said energy with an energy reflective target when said vehicle is in said horizontal fine position location;

(k) sensing said reflected energy with energy sensing means mounted on said vehicle;

(l) generating with said energy sensing means a signal in response to sensing said reflected energy;

(m) communicating said signal from said energy sensing means to said control means;

(n) causing with said control means said vehicle to stop at said horizontal fine position location;

(o) generating a signal having a first non-ambiguous binary value corresponding to said vertical start address;

(p) communicating said signal having said first value to control means for said carriage;

(q) receiving in said control means a second non-ambiguous binary value corresponding to said vertical destination address;

(r) comparing in said control means said first and second values;

(s) determining if a load is present on said carriage;

(t) biasing said second value to a bin high non-ambiguous binary value corresponding to said bin high rough position zone if a load is present on said carriage;

(u) biasing said second value to a bin low non-ambiguous binary value corresponding to said bin low rough position zone if a load is not present on said carriage;

(v) causing with said control means said carriage to move to one of said bin high and bin low rough position zones to which said biased second value corresponds;

(w) generating a signal having said biased second value;

(x) communicating said signal having said biased second value to said control means whereby said vehicle is designated as being located in said one of said bin high and said bin low rough position zones;

(y) projecting energy from energy source means mounted on said carriage;

(z) reflecting said energy when said carriage is in said fine position location;

(aa) sensing said energy with said energy sensing means mounted on said carriage;

(bb) generating with said energy sensing means a signal in response to sensing said reflected energy;

(cc) communicating said signal from said energy sensing means to said control means; and

(dd) causing with said control means said carriage to stop at said fine position location.