Method for docking an autonomous mobile unit with the use of a light beam

• US 6,278,917 B1
• Filed: 05/12/2000
• Issued: 08/21/2001
• Est. Priority Date: 09/01/1997
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Zillich, Michael, Bauer, Rudolf
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): To, Tuan C
• Application Number:
  US09/486,752
• Time in Patent Office: 466 Days
• Field of Search: 701/23, 364/424.01, 364/424.02, 364/513, 180/167, 180/169, 358/103, 318/587
• US Class Current: 701/23
• CPC Class Codes: G05D 1/0225 involving docking at a fixed facility, e.g. base station or loading bay parking aids B62D15/027
• CPC Class Codes: G05D 1/0236 in combination with a laser lasers per se H01S
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• CPC Class Codes: G05D 1/0255 using acoustic signals, e.g. ultra-sonic singals sonar systems designed for anti-collision purposes G01S15/93
• CPC Class Codes: G05D 1/0272 comprising means for registering the travel distance, e.g. revolutions of wheels measuring distance traversed on the ground by vehicles, e.g. using odometers G01C22/00

Abstract

The invention includes a method for docking autonomous mobile units. Travel maneuvers are specified with which constricted space conditions can be taken into consideration. Further, different motion paths are recited that are to be sequentially traversed in order to locate a guide beam and in order to be able to dock reliably and dependably at a docking device. Preferably, a slot-shaped guide beam residing perpendicular to a travel surface of the unit is provided, and position-sensitive detectors for this guide beam are present on the unit, these being arranged parallel to the travel surface of the unit. The exact rotation (beta) of the unit relative to the docking device can be identified on the basis of the guide beam and the detectors, whereby the unit knows its approximate configuration in the space on the basis of ultrasound and odometry measurements. The invention can particularly be utilized in household robots or industrial robots.

Claims

1. A method for docking positioning of an autonomous mobile unit at a docking device using a guide beam, comprising the steps of:

a) prescribing destination coordinates and a rotated attitude of the docking device in a world coordinate system at commencement of travel of the autonomous mobile unit thereby affording the autonomous mobile unit information concerning alignment with the guide beam and position and rotated attitude of the autonomous mobile unit;

b) self-orienting of the autonomous mobile unit in surroundings of the autonomous mobile unit using at least one distance-measuring sensor, with which the autonomous mobile unit measures a distance to an obstacle in the surroundings, and odometry, with which the autonomous mobile unit measures a path distance traversed since the commencement of travel, and wherein the autonomous mobile unit calculates coordinates of the autonomous mobile unit in the world coordinate system and positional uncertainty of the autonomous mobile unit based on at least one of the measurements of distance to an obstacle and the traversed path distance;

c) moving the autonomous mobile unit to a starting position for a docking event wherein the autonomous mobile unit aligns with respect to the rotated attitude of the autonomous mobile unit such that a detector for detecting the guide beam and the guide beam can interact; and

d) moving the autonomous mobile unit in the direction of the destination coordinates when the detector does not detect the guide beam in order to seek the guide beam wherein the movement of the autonomous mobile unit in the direction of the destination coordinates in conjunction with the detector for detecting the guide beam is used for docking positioning of the autonomous mobile unit.

2. The method according to claim 1, wherein the autonomous mobile unit travels one of forward and in reverse to the starting position.

3. The method according to claim 1, wherein a position of the autonomous mobile unit is redetermined relative to the guide beam after detecting the guide beam based on a known position of the autonomous mobile unit in combination with the detector in order to minimize the positional uncertainty transversely relative to the guide beam.

4. The method according to claim 1, wherein the autonomous mobile unit moves such that the autonomous mobile unit crosses the guide beam a plurality of times when the detector is seeking to detect the guide beam.

5. The method according to claim 4, wherein the of autonomous mobile unit moves in a meander-like search path.

6. The method according to claim 5, wherein turning maneuvers for moving in the meander-like search path change with a distance of the autonomous mobile unit from a suspected position of the guide beam.

7. The method according to claim 4, wherein the autonomous mobile unit seeks the guide beam by first moving toward the docking device and crossing a suspected course of the guide beam, then moving a distance parallel to the suspected course of the guide beam, and subsequently crossing the guide beam in the direction of the docking device.

8. The method according to claim 3, wherein the autonomous mobile unit moves along a zig-zag-shaped search path that lies transverse relative to a suspected course of the guide beam, by moving forward and in reverse without turning maneuvers.

9. The method according to claim 1, wherein when the autonomous mobile unit detects the guide beam, the autonomous mobile unit follows the guide beam to the docking device through use of the detector.

10. The method according to claim 1, wherein the autonomous mobile unit is moved to approach the starting position by at lease one of, rotating into a starting rotated attitude and rotating and then moving toward the starting position when at least one of spatial conditions and three-wheel kinematics of the autonomous mobile unit preclude one of the starting position and the starting rotated attitude to be reached through solely forward, or reverse travel and steering.