Autonomous mowing vehicle and apparatus for detecting boundary of mowed field

• US 5,528,888 A
• Filed: 12/22/1994
• Issued: 06/25/1996
• Est. Priority Date: 12/27/1993
• Status: Expired due to Fees

• Current Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Original Assignee: Fuji Heavy Industries Limited (Subaru Corp.)
• Inventors: Miyamoto, Yasuhiko, Nagano, Toshihiro
• Primary Examiner(s): MELIUS, TERRY L
• Application Number:
  US08/362,258
• Time in Patent Office: 551 Days
• Field of Search: 56/10.2 F, 56/10.2 A, 56/10.2 D, 180/167, 180/168, 180/169, 364/424.02, 364/424.07
• US Class Current: 56/10.20F
• CPC Class Codes: A01B 69/008 automatic
• CPC Class Codes: A01D 2101/00 Lawn-mowers
• CPC Class Codes: A01D 34/008 for automated or remotely controlled operation
• CPC Class Codes: G05D 1/0227 using mechanical sensing means, e.g. for sensing treated area
• CPC Class Codes: G05D 1/0278 using satellite positioning signals, e.g. GPS

Abstract

An apparatus for detecting a extending boundary between fields mowed and not mowed by an cutting blade mechanism of an autonomous vehicle for the mowing of lawn grass, comprises a plurality of rocking members provided to be aligned in a lateral direction of the vehicle under a body of the vehicle, a plurality of rocking condition sensors provided to detect rocking conditions of the respective rocking members, and a control unit provided to determine a boundary between a rocking member rocked by taller lawn grass and a rocking member not rocked as the boundary between the mowed field and not mowed field in response to signals from the rocking condition sensors. There is further provided a method for shifting the vehicle to a ready position of a next lane to be mowed in the work area based on the result of the detection by the boundary detecting apparatus.

Claims

1. An apparatus for detecting an extending boundary between fields mowed and not mowed by a cutting blade mechanism of an autonomous vehicle for the mowing of lawn grass, comprising:

a plurality of rocking members provided to be aligned in a lateral direction of the vehicle under a body of the vehicle;

plurality of rocking condition sensors provided to detect rocking conditions of the respective rocking members; and

a control unit provided to determine a boundary between a rocking member rocked by the lawn grass and a rocking member not rocked as the boundary between the mowed field and not mowed field in response to signals from said rocking condition sensors.

2. The apparatus according to claim 1, wherein said control unit comprises:

boundary recognition means responsive to said signals from said rocking condition sensors for recognizing positions of the boundary with respect to the body of the vehicle every predetermined control interval;

running control means for calculating an offset of the vehicle body to the side from a predetermined target position in accordance with a position of the boundary recognized by said running control means;

vehicle control means for calculating a target steering angle of wheels of the vehicle so as to reduce said offset; and

steering control means for controlling an actual steering angle of said wheels to said target steering angle.

3. The apparatus according to claim 2, wherein said control unit further comprises:

running distance detection means for calculating a running distance by which the vehicle has run for said predetermined control interval;

wherein

said running control means further calculates a deviation angle of a direction to which the vehicle is running, with respect to the extending boundary based on said running distance and a difference between first and second boundary positions sequentially recognized by said boundary recognition means; and

said vehicle control means calculates said target steering angle based on said deviation angle in addition to said offset.

4. The apparatus according to claim 1, further comprising:

a shaft extending in the lateral direction of the vehicle to rotatably support said plurality of rocking members.

5. The apparatus according to claim 1, wherein each of said plurality of rocking members comprises:

a sensing portion extending downwardly from a rocking center and having a lower end with a clearance from the ground approximately same as a minimum ground clearance of said cutting blade mechanism; and

a switching portion facing corresponding one of said plurality of sensors to change the status thereof when each of said rocking members is rotated by the lawn grass not mowed.

6. The apparatus according to claim 5, wherein each of said plurality of sensors is a microswitch being turned on by said switching portion of the corresponding one of said rocking members.

7. An autonomous mowing vehicle having a body, and at least one cutting blade under said body, comprising:

boundary detection means for detecting a field mowed by said cutting blade and a field not mowed by said cutting blade;

boundary recognition means for recognizing a presence of a boundary between the field mowed and the field not mowed and for recognizing an absence of the boundary, respectively; and

running control means for controlling the vehicle so as to run along said boundary when the presence of said boundary is recognized by said boundary recognition means and to shift said vehicle to a mowing lane when the absence of a boundary is recognized by said boundary recognition means; and

said boundary detection means includes two sets of boundary detection mechanisms provided on front and rear sides with respect to said cutting blade respectively.

8. An autonomous vehicle having a body and at least one cutting blade under said body, comprising:

boundary detection means for detecting a field mowed by said cutting blade and a field not mowed by said cutting blade;

boundary recognition means for recognizing a presence and absence of a boundary between said field mowed and said field not mowed;

running control means for controlling said vehicle so as to run along said boundary when said presence of said boundary is recognized by said boundary recognition means and to shift a mowing lane when said absence of a boundary is recognized by said boundary recognition means; and

said boundary detection means includes two sets of boundary detection mechanisms provided on front and rear sides with respect to said cutting blade and alternately detects said boundary while said vehicle moves respectively forwardly and rearwardly and changes from a lane to another lane along said boundary.

9. An autonomous mowing vehicle having a body and at least one cutting blade under said body, comprising:

boundary detection means for detecting a field mowed by said cutting blade and a field not mowed by said cutting blade;

boundary recognition means for recognizing a presence and absence of a boundary between said field mowed and said field not mowed;

running control means for controlling said vehicle so as to run along said boundary when said presence of said boundary is recognized by said boundary recognition means and to shift a mowing lane when said absence of a boundary is recognized by said boundary recognition means; and

said boundary detection means includes two sets of boundary detection mechanisms provided on left and right sides with respect to said cutting blade, respectively, in a case where either forward running or reverse running is performed for the mowing along said boundary.

10. An autonomous mowing vehicle having a body, and at least one cutting blade under said body, comprising:

boundary detection means for detecting a field mowed by said cutting blade and a field not mowed by said cutting blade;

boundary recognition means for recognizing a presence and absence of a boundary between said field mowed and said field not mowed;

running control means for controlling said vehicle so as to run along said boundary when said presence of said boundary is recognized by said boundary recognition means and to shift a mowing lane when said absence of a boundary is recognized by said boundary recognition means; and

said boundary detection means includes only one set of boundary detection mechanism provided on only one side of said cutting blade for detecting a spiral geometry of said boundary as said vehicle spirally moves along the boundary.

11. A method for controlling the autonomous running of a vehicle having at least one cutting blade provided under a body of said vehicle for mowing at a work area, the method comprising the steps of:

locating a ready position of said vehicle by using a D-GPS system;

generating a route from said ready position to a mowing start position;

moving said vehicle to said mowing start position;

mowing a periphery of said work area by reference to data stored in a memory;

detecting a field mowed by said cutting blade and a field not mowed;

recognizing presence and absence of a boundary between the mowed field and the not mowed field by a detection mechanism;

controlling the vehicle so as to run along said boundary when the presence of said boundary is recognized;

advancing the vehicle by a first predetermined distance after the absence of said boundary is recognized in order to avoid leaving lawn grass without being mowed;

backing the vehicle by a second predetermined distance after the advance by the first predetermined distance; and

shifting the vehicle obliquely to a next lane to be mowed.

14. The method according to claim 11, further comprising the steps of

repeating the above steps until said absence of said boundary is recognized all over said work area;

moving said vehicle to a next work area and repeating the steps above; and

returning said vehicle to a goal position near said ready position.

12. A method for controlling the autonomous running of a vehicle having at least one cutting blade provided under a body of said vehicle for mowing at a work area, the method comprising the steps of:

locating a ready position of said vehicle by using a D-GPS system;

generating a route from said ready position to a mowing start position;

moving said vehicle to said mowing start position;

mowing a periphery of said work area by reference to data stored in a memory;

detecting a field mowed by said cutting blade and a field not mowed;

recognizing presence and absence of a boundary between the mowed field and the not mowed field by a detection mechanism;

controlling the vehicle so as to run along said boundary when the presence of said boundary is recognized;

switching back the vehicle after the absence of said boundary is recognized;

backing the vehicle by a second predetermined distance after the advance by the first predetermined distance; and

shifting the vehicle obliquely to a next lane to be mowed.

15. The method according to claim 12, further comprising the steps of

repeating the above steps until said absence of said boundary is recognized all over said work area;

moving said vehicle to a next work area and repeating the steps above; and

returning said vehicle to goal a position near said ready position.

13. An apparatus for detecting a boundary extending between fields mowed and not mowed by a cutting blade mechanism of an autonomous mowing vehicle, comprising distance detecting means for calculating a running distance by integrating vehicle speed and for generating a distance signal, estimated position detecting means responsive to said distance signal and a directional change signal from a dead reckoning position detecting means for determining an estimated present position of said vehicle by calculating a total running distance from a reference point and for producing an estimated position signal, fixed communication means for transmitting differential information of a geographical position of said vehicle calculated by a group of satellites and for producing a position signal, and position detecting means responsive to said position signal for determining a present position of said vehicle in accordance with navigation messages from said group of satellites and for generating a present position signal, the apparatus further comprising:

a plurality of rocking members supported on a shaft in said apparatus under a body of said vehicle for rocking in a moving direction of said vehicle when a lower end of said rocking members touches grass;

a plurality of rocking condition sensors mounted on said body for detecting a rocking condition of said rocking members and to produce a rocking condition signal when an upper sensing portion of said rocking members touches said rocking condition sensors;

boundary recognition means responsive to said rocking condition signal for determining said boundary and to generate a positional data signal; and

control means responsive to said positional data signal, said distance signal, said estimated position signal and said present position signal for determining said boundary between a group of said rocking members rocked by the grass and another group of said rocking members unrocked by said grass so as to correctly detect said boundary, so that responsive thereto the vehicle performs optimum mowing by said cutting blade mechanism.