Process for preparing an area plan having a cellular structure and comprising a unit moving automatically and positioned in said area using sensors based on wave reflection

• US 6,205,380 B1
• Filed: 12/18/1998
• Issued: 03/20/2001
• Est. Priority Date: 07/02/1996
• Status: Expired due to Fees

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: Wienkop, Uwe, Bauer, Rudolf
• Primary Examiner(s): Cuchlinski, Jr., William A.
• Assistant Examiner(s): PIPALA, EDWARD J
• Application Number:
  US09/202,531
• Time in Patent Office: 823 Days
• Field of Search: 701/1, 701/23, 701/25, 701/300, 318/568.1, 318/568.16, 318/587, 180/167, 180/169, 901/1
• US Class Current: 701/23
• CPC Class Codes: G05D 1/0221 involving a learning process
• 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 1/0274 using mapping information stored in a memory device navigation using map-matching G01C21/30

Abstract

The entry and the deletion of the degree of occupancy values in cellularly structured environment maps of autonomous mobile units is improved with the method. Dependent on the measuring directions of ultrasound sensors, different sectors in which the degrees of occupancy value are separately incremented are defined for each cell of the cellularly structured environment map. This has the advantage that an obstacle measured by different sensors only leads to an incrementation or a de-incrementation of the occupancy degree of a respective cell when this measurement ensued from the same measuring direction with respect to the cellularly structured environment map. Dynamic objects in the measurement area of the autonomous mobile unit can thus be more quickly deleted from the map and timeout measurements that have arisen due to reflections of echos do not lead to really existing objects being deleted from the map.

Claims

1. A method for producing a cellularly structured environment map of a self-propelled mobile unit which orients itself in an environment using sensors based on wave reflection, comprising the steps of:

determining a distance of the sensor from an environmental object a position of the object as undefined location on a circular arc segment of a circle by at least one sensor with the sensor as center of the circle and the distance as radius, the circular arc segment being limited by a measuring area of the sensor;

determining an alignment of the sensor with respect to the cellularly structured environment map as a measuring beam;

dividing a cell of the environment map into at least two sensor alignment areas as sectors and determining an occupancy degree of the cell as a function of the alignment of the sensor; and

determining an overall occupancy degree of the cell from the occupancy degrees of the sectors of the cell.

2. The method according to claim 1,

wherein a blind zone in measuring direction of at least one sensor is prescribed dependent on a measuring imprecision of the sensor, said blind zone adjoining the sensor; and

wherein the occupancy degree of the sector of a cell of the environment map that is located within the blind zone is not modified.

3. The method according to claim 1,

wherein at least one maximum sensor range is prescribed dependent on a running time criterion for a maximum running time between an emitted measuring pulse and a received signal echo;

and

wherein the occupancy degree of the sector of a cell of the environment map that is located outside the sensor range is not modified.

4. The method according to claim 1, wherein dependent on a measuring interval, the occupancy degree of a respective sector of at least one cell that is located on the measuring beam that proceeds at symmetry axis of a conical wave front from the sensor to the environmental object is negatively incremented.

5. The method according to claim 1, wherein the occupancy degree of the sector of a cell that is located on the circular arc segment is positively incremented.

6. The method according to claim 1, wherein a maximum occupancy degree is prescribed per cell, the maximum occupancy degree not being allowed to be exceeded given an additive linkage of all occupancy degrees stored per cell for sectors.

7. The method according to claim 1, wherein an increment with which the occupancy degree is incremented is dependent on the distance of the environmental object.

8. The method according to claim 7, wherein the increment for a relatively small distance is selected greater than the increment for a relatively great distance.

9. The method according to claim 1, wherein an increment with which the occupancy is incremented is dependent on a moving speed of the self-propelled mobile unit.

10. The method according to claim 9, wherein the increment is selected greater for a relatively high travel speed than for a low travel speed.

11. The method according to claim 1,

wherein an exact position of a coordinate reference point of a coordinate system underlying the cellularly structured environment map within an originating cell of the environment is employed as an intrinsic position of the self-propelled mobile unit at the point in time of a measurement;

and

wherein an exact alignment and position of the sensor relative to the coordinate system is determined for a respective measurement based on the intrinsic position of the unit and the location of the unit, and on a position of the sensor at the unit.

12. The method according to claim 1, wherein cells of different sizes are employed for producing the environment map.