Navigational control system for an autonomous vehicle

• US 5,111,401 A
• Filed: 05/19/1990
• Issued: 05/05/1992
• Est. Priority Date: 05/19/1990
• Status: Expired due to Fees

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: the united states of america as represented by the secretary of the navy
• Inventors: Everett, Hobart R. Jr., Gilbreath, Gary A., Laird, Robin T.
• Primary Examiner(s): Black, Thomas G.
• Application Number:
  US07/531,483
• Time in Patent Office: 717 Days
• Field of Search: 364/424.02, 364/443, 180/167-169, 318/568.12
• US Class Current: 701/24
• CPC Class Codes: G05D 1/0242 using non-visible light signals, e.g. IR or UV signals
• CPC Class Codes: G05D 1/0246 using a video camera in combination with image processing means
• 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

A navigational control system directs an autonomous vehicle to travel along a floor from a first location to a destination within an environment, and includes a propulsion module having a processor that receives navigation control signals for directing the motion of the module and provides position signals. At least one reflective, encoded stripe is applied to the floor of the environment. If stripe detecting means, mounted to the module, detects the stripe, recognition signals are provided. Ranging means mounted to the module measures the range between the vehicle and any object within a predetermined distance of the vehicle. A host computer determine an initial path for the vehicle to follow in order to reach the destination; provides the navigation control signals to the processor; receives data from the processor for determining an estimated dead-reckoning position of the vehicle; and receives the recognition signals for directing the vehicle to follow the stripe if any of the coordinates of the stripe are coincident with the coordinates of the initial path. The position estimation of the vehicle is updated by the host computer as the vehicles travels along the initial path. The updated position is functionally related to the coordinates of the detected region of the stripe and to the estimated dead-reckoning position. If the ranging means measures an obstruction blocking the initial path, the module is directed to avoid the obstruction.

Claims

1. A navigational control system for directing an autonomous vehicle to travel along a generally planar surface, such as a floor, from a first location to a destination within an operating environment, comprising:

an autonomous vehicle including a self-propelled and steerable propulsion module providing position signals corresponding to a dead-reckoning determination of a position and bearing of said module with respect to a reference position;

at least one long, narrow guidepath stripe applied to said surface of said environment to define a desired pathway having predetermined coordinates along which said module may be selectively guided, said guidepath stripe encoded with a plurality of displacement markers positioned at predetermined intervals along the length of said guidepath stripe, said markers having predetermined coordinates;

stripe detecting means mounted to said module for detecting said guidepath stripe and said displacement markers, and for providing recognition signals when said stripe detecting means detects said guidepath stripe and for providing recognition signals when said guidepath stripe detection means detects one of said displacement markers;

ranging means mounted to said module for measuring the range between said module and any object and for providing range signals corresponding to said measured range; and

processing means for determining an optimal path for said module to follow to said destination, said processing means;

coupled to receive said position signals for monitoring said dead-reckoning determined position of said module along said path;

coupled to receive said range signals for revising said path in order to avoid an obstacle blocking said path; and

coupled to receive said recognition signals for revising said dead-reckoning position of said module into an updated position;

said processing means for revising said optimal path in response to said updated position; and

for providing navigational control signals to guide said module along said optimal path.

2. The navigational control system of claim 1 wherein:

said processing means maintains a mathematical model of said operating environment and updates said updated position determination of said module within said model in real-time.

3. The navigational control system of claim 2 wherein:

said path has coordinates encoded within said mathematical model; and

said module is directed to follow at least some portion of said guidepath stripe when at least some portion of said guidepath stripe is oriented in a general direction of an intended path.

4. The navigational control system of claim 3 wherein:

said ranging means includes a plurality of ultrasonic transducers.

5. The navigational control system of claim 4 wherein:

said guidepath stripe detecting means includes;

at least one video camera mounted to said module such that said lens is directed to towards said floor for providing a video signal corresponding to detection of said guidepath stripe,

at least one light source mounted to said module and directed to illuminate said guidepath stripe, and

digitizing means mounted to said module and coupled to receive said video signal for providing said recognition output to said processing means.

6. The navigational control system of claim 5 wherein:

said guidepath stripe is made of a material that is invisible under ambient lighting conditions and fluoresces when irradiated with ultraviolet light; and

said displacement markers are areas of said material having a predetermined shape that are applied contiguous to the edge of said guidepath stripe at said predetermined intervals along the length of said guidepath stripe so as to produce recognizable discontinuity patterns along the edge of said guidepath stripe.

7. The navigational control system of claim 6 wherein:

said processing means is a host computer that includes programming that represents said mathematical model of said environment, said model includes parameters of Cartesian coordinates of permanent features of said environment and said coordinates of said guidepath stripe, said host computer determines said initial optimum and revised paths by using a path-planning algorithm operating within the context of said parameters.

8. The navigational control system of claim 7 wherein:

said digitizing means is a video line digitizer.

9. A navigational control system for directing an autonomous vehicle to travel along a generally planar surface, such as a floor, from a first location to a destination within an operating environment, comprising:

an autonomous vehicle including a self-propelled and steerable propulsion module providing position signals corresponding to a dead-reckoning determination of a position and bearing of said module with respect to a reference position;

at least one long, narrow guidepath stripe of reflective material applied to said surface of said environment to define a desired pathway having predetermined coordinates along which said module may be selectively guided, said guidepath stripe encoded with a plurality of displacement markers positioned at predetermined intervals along the length of said guidepath stripe, said markers having predetermined coordinates, said guidepath stripe contrasting with said floor;

stripe detecting means mounted to said module for detecting said guidepath stripe and said displacement markers, and for providing recognition signals when said stripe detecting means detects said guidepath stripe and for providing recognition signals when said guidepath stripe detection means detects one of said displacement markers;

ranging means mounted to said module for measuring the range between said module and any object and for providing range signals corresponding to said measured range; and

processing means for determining an optimal path for said module to follow to said destination, said processing means;

coupled to receive said position signals for monitoring said dead-reckoning determined position of said module along said path;

coupled to receive said range signals for revising said path in order to avoid an obstacle blocking said path; and

coupled to receive said recognition signals for revising said dead-reckoning position of said module into an updated position;

said processing means for revising said optimal path in response to said updated position; and

for providing navigational control signals to guide said module along said optimal path.

10. The navigational control system of claim 9 wherein:

said processing means maintains a mathematical model of said operating environment and updates said updated position determination of said module within said model in real-time.

11. The navigational control system of claim 10 wherein:

said path has coordinates encoded within said mathematical model; and

said module is directed to follow at least some portion of said guidepath stripe when at least some portion of said guidepath stripe is oriented in a general direction of an intended path.

12. The navigational control system of claim 11 wherein:

said ranging means includes a plurality of ultrasonic transducers.

13. The navigational control system of claim 11 wherein:

said stripe detecting means includes;

at least one video camera mounted to said module such that

said lens is directed to towards said floor for providing a video signal corresponding to detection of said guidepath stripe,

at least one light source mounted to said module and directed to illuminate said guidepath stripe, and

digitizing means mounted to said module and operably coupled to receive said video signal for providing said recognition output to said processing means.

14. The navigational control system of claim 13 wherein:

said displacement markers are areas of said guidepath material having a predetermined shape that are applied contiguous to the edge of said guidepath stripe at said predetermined intervals along the length of said guidepath stripe so as to produce recognizable discontinuity patterns along the edge of said guidepath stripe.

15. The navigational control system of claim 14 wherein:

said processing means is a host computer that includes programming that represents said mathematical model of said environment, said model includes parameters of Cartesian coordinates of permanent features of said environment and said coordinates of said guidepath stripe, said host computer determines said initial optimum and revised paths by using a path-planning algorithm operating within the context of said parameters.

16. The navigational control system of claim 15 wherein:

said digitizing means is a video line digitizer.

17. A navigational control system for directing an autonomous vehicle to travel along a generally planar surface, such as a floor, from a first location to a destination within an operating environment, comprising:

an autonomous vehicle including a self-propelled and steerable propulsion module providing position signals corresponding to a dead-reckoning determination of a position and bearing of said module with respect to a reference position;

at least one long, narrow guidepath stripe applied to said surface of said environment to define a desired pathway having predetermined coordinates along which said module may be selectively guided, said guidepath stripe encoded with a plurality of displacement markers positioned at predetermined intervals along the length of said guidepath stripe, said markers having predetermined coordinates, said guidepath stripe is invisible when irradiated with visible light and fluoresces when irradiated with ultraviolet light;

stripe detecting means mounted to said module for detecting said guidepath stripe and said displacement markers, and for providing recognition signals when said stripe detecting means detects said guidepath stripe and for providing recognition signals when said guidepath stripe detection means detects one of said displacement markers;

ranging means mounted to said module for measuring the range between said module and any object and for providing range signals corresponding to said measured range; and

processing means for determining an optimal path for said module to follow to said destination, said processing means;

coupled to receive said position signals for monitoring said dead-reckoning determined position of said module along said path;

coupled to receive said range signals for revising said path in order to avoid an obstacle blocking said path; and

coupled to receive said recognition signals for revising said dead-reckoning position of said module into an updated position;

said updated position functionally related to said position encoded in said position signals and to said position corresponding to said location associated with said recognition signals;

said processor means for revising said optimal path in response to said updated position; and

for providing navigational control signals to guide said module along said optimal path.

18. The navigational control system of claim 17 wherein:

said processing means maintains a mathematical model of said operating environment and updates said updated position determination of said module within said model in real-time.

19. The navigational control system of claim 18 wherein:

said path has coordinates encoded within said mathematical model; and

said module is directed to follow at least some portion of said guidepath stripe when at least some portion of said guidepath stripe is oriented in a general direction of an intended path.

20. The navigational control system of claim 19 wherein:

said ranging means includes a plurality of ultrasonic transducers.

21. The navigational control system of claim 20 wherein:

said stripe detecting means includes;

at least one video camera mounted to said module such that said lens is directed to towards said floor for providing a video signal corresponding to detection of said guidepath stripe,

at least one ultraviolet light source mounted to said module and directed to illuminate said guidepath stripe, and

digitizing means mounted to said module and coupled to receive said video signal for providing said recognition output to said processing means.

22. The navigational control system of claim 21 wherein:

said guidepath stripe is made of a material that is invisible under ambient lighting conditions and fluoresces when irradiated with ultraviolet light; and

said displacement markers are areas of said material having a predetermined shape that are applied contiguous to the edge of said guidepath stripe at said predetermined intervals along the length of said guidepath stripe so as to produce recognizable discontinuity patterns along the edge of said guidepath stripe.

23. The navigational control system of claim 22 wherein:

said processing means is a host computer that includes programming that represents said mathematical model of said environment, said model includes parameters of Cartesian coordinates of permanent features of said environment and said coordinates of said guidepath stripe, said host computer determines said initial optimum and revised paths by using a path-planning algorithm operating within the context of said parameters.