Abstract:
Autonomous land maintenance equipment is provided that includes an obstacle detection device, having a predetermined detecting range, a receiver receiving for collecting waste material and a structure for emptying the waste material from the receiver, such that the waste material is deposited outside of the range of the obstacle detection device.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of International Application No. PCT/GB03/00348, filed Jan. 28, 2003, which claims priority from U.K. Patent Application No. 0207111.6, filed Mar. 26, 2002. The disclosures of both applications are incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION  
       [0002]     This invention relates to autonomous land maintenance equipment, and more specifically to autonomous land maintenance equipment that has emptying means.  
         [0003]     Conventionally land maintenance such as grass mowing is carried out by use of a manually operated machine. Some mowing machines are capable of carrying out various tasks other than mowing grass, such as leaf collection, scarifying, slitting and hollow coring, all of which can involve collecting debris. For the purposes of describing the background to related art, mowing grass will be used as the example. Whilst the mowing operation is carried out, cut grass is collected in a bag or box carried on the machine. Often the bag or box (otherwise known as a catcher) reaches its capacity several times during the mowing task and therefore has to be emptied before the task can continue. Generally the collected grass cuttings are deposited in one particular area, either on the ground or in a trailer or skip, which will generate a pile after several box or bag loads are emptied. The grass collected at sports facilities is mainly removed from the site either by transferring the pile from the ground to a skip or trailer or by just using the trailer or skip, thus keeping the area tidy. The operation of transferring the grass cuttings from the mower to the deposit point involves the operator doing one of two things depending upon the machine used. Some machines require the operator to lift the bag or box from the machine and manually empty it by shaking it at about standing height so the grass falls on top of a pile or into a trailer or skip. Other machines are fitted with an automatic mechanism that empties the grass at the pull of a lever or the press of a button.  
         [0004]     Autonomous vehicles require obstacle detection devices to aid the vehicle in carrying out its task, and more importantly to provide a method of bringing the vehicle to a safe standstill if a fault should occur. There are many different devices used by autonomous vehicles including various different designs of physical sensing bumpers, ultrasonic sensors, laser reflected detection systems or any other emitted/reflected energy wave detection system. Any system used has to be fail safe to protect the vehicle and any person in the working environment and should not be over ridden when the vehicle operates autonomously. If the obstacle detection devices detect an obstacle or person, the vehicle must come to a complete stop before the main structure of the vehicle hits the obstacle and causes any damage or injures the person. This means that whatever system of obstacle detection is used, the main body of a vehicle will never be any closer than its stopping distance from an obstacle during normal working conditions.  
         [0005]     A problem that arises is that any waste material deposited within this range will trigger the obstacle detection device and stop the vehicle. As a result, known automated land maintenance equipment either requires the machine to be shut down and the grass catcher manually emptied, or continuously disperses the grass cuttings, for example as a mulch, as it operates.  
       SUMMARY OF THE INVENTION  
       [0006]     According to the present invention there is provided automated land maintenance equipment that comprises a vehicle, where the vehicle comprises operating means for performing a maintenance operation; receiving means for receiving waste material delivered from the operating means; guidance means for controlling the movement of the vehicle; and obstacle detecting means having a predetermined detecting range; and the equipment further comprises emptying means for emptying the receiving means; wherein, upon activation of the emptying means, the waste material is deposited beyond the obstacle detecting range.  
         [0007]     Waste material may comprise grass cuttings, leaves, hollow cores, thatch or general litter.  
         [0008]     The invention is applicable to all variants of land maintenance equipment for commercial or domestic use. Embodiments in accordance with the present invention have guidance means that comprise any of the following positioning systems to enable it to navigate around the work environment autonomously: GPS, DGPS, Real Time Kinematic GPS, Laser scanner, buried transponders or wire guidance. The receiving means may be either a bag or box container that may be positioned to the front or the rear of the vehicle. The vehicle may be able to navigate its way to a grass/debris collection point that may be done either when the receiving means is full or just before it is full.  
         [0009]     In preferred embodiments of the invention, the emptying means comprises a supporting arm which carries the receiving means and which is mounted on a frame of the vehicle for pivotal movement about a pivot axis which itself is displaceable relatively to the frame of the vehicle, an actuator being provided for displacing the pivot axis relatively to the frame of the vehicle, and control means being provided to control movement of the supporting arm about the pivot axis.  
         [0010]     Preferably, the support arm is mounted on a lever for pivotal movement relative to the lever about the pivot axis, the lever being pivotably mounted on the frame of the vehicle, and the actuator acting between the frame of the vehicle and the lever.  
         [0011]     Preferably, the control means comprises a cable that extends between the frame of the vehicle and a point on the support arm that is spaced from the pivot axis.  
         [0012]     Preferably, the emptying means, when activated, displaces the receiving means from a lower level, at which the receiving means is positioned to receive waste material delivered from the operating means, to a higher level from which the waste material is deposited from the receiving means.  
         [0013]     The receiving means may be lifted to the required position by a controlled actuated mechanism, constituting the emptying means, onboard the autonomous vehicle to empty it; or alternatively a larger transporting trailer or skip at the collection point may have a controlled actuated mechanism, constituting the emptying means, that may lift the receiving means from the autonomous vehicle and empty it. The receiving means then may or may not be replaced. The receiving means may be self-replenishing in that the receiving means may be deposited in its entirety and replaced with further receiving means already on the vehicle.  
         [0014]     The obstacle detecting means may comprise physical tactile bumpers, ultrasonic sensors or any emitted wave detection system. Any of these obstacle detection systems may be part of the main structure of the vehicle and remain in place whilst said controlled actuated mechanism lifts the receiving means from its normal working position.  
         [0015]     Alternatively the obstacle detecting means may be attached to the receiving means or controlled actuated mechanism and may be lifted. In this case, the range of the obstacle detection device applies when the receiving means is in its normal working position.  
         [0016]     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a side elevation of an autonomous grass/lawn mower showing the vehicle with the grass catcher in its normal working position.  
         [0018]      FIG. 2  corresponds to  FIG. 1  but shows the vehicle with a protective cowling removed.  
         [0019]      FIG. 3  shows the vehicle of  FIG. 1  with the grass catcher in the elevated position for grass dumping.  
         [0020]      FIGS. 4, 5 , and  6  correspond to  FIG. 1  but show alternative embodiments.  
         [0021]      FIG. 7  corresponds to  FIG. 3  but shows an alternative embodiment. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0022]      FIG. 1  shows autonomous land maintenance equipment in the form of a grass/lawn mower  26  having a protective cowling  4  supported by a chassis  10  seen in  FIG. 2 . Ground engaging wheels  3 ,  5  are used to move the mower  26 . The mower has guidance means that comprises a laser scanner  7  that is used to determine the vehicle position in the task environment. The cowling  4  supports a front bumper  1  and rear bumper  6  acting as obstacle detecting means. The distance between the front of the cowling  4  and the front of the front bumper is equivalent to the stopping distance of the vehicle  26  as it moves in direction A. The grass/lawn mower  26  uses operating means in the form of a cutter unit  2  to cut the grass; the grass is then delivered to the receiving means in the form of a grass catcher, which comprises upper  12 , and lower  25 , sections via a shoot  11 . The grass catcher  12 ,  25  is attached to the main chassis  10  by a lifting arm consisting of an upper arm  9  and a lower arm  8 .  
         [0023]     The preferred workings of the invention of the grass/lawn mower  26  are shown in more detail in  FIG. 2 . The mower  26  has emptying means for emptying the grass catcher  12 ,  25 . This emptying means comprises lower and upper arms  8 ,  9  operated by a lift actuator  15 . The method of lifting the grass catcher  12 ,  25  beyond the front bumper  1  vertically and horizontally is achieved by extending the lift actuator  15 . The lift actuator  15  is rotatable about a location pin  17  and acts on a lower arm pin  14 . The lower arm pin  14  is rotatable within the assembly of lower arm  8 . The lower arm  8  is rotatable about a horizontal pin  13  so that when the lift actuator  15  is extended to act on the lower arm pin  14 , the lower arm  8  rotates anticlockwise about pin  13 . The lower arm  8  is in turn attached to the upper arm  9  by an upper arm pin  16 . The upper arm  9  rotates about the upper arm pin  16  as the lift actuator  15  is extended, as it is attached to the chassis  10  by a cable  20  which may pull the back section of the upper arm  9  down, thus lifting the forward section up. The cable  20  rotates about a fixed point  19  on the chassis  10 . The result of the extension of the actuator may be seen in  FIG. 3  where the grass catcher  12 ,  25  is lifted clear of the normal working extremities of the lawn/grass mower  26  beyond the front bumper  1 , and therefore beyond the range of the obstacle detecting means. The grass cuttings are then released from the grass catcher  12 ,  25  by extending a grass catcher actuator  23  fixed at a pin  24  and acting on a pin  22 . The extension rotates the lower section grass catcher  25  about a hinge  21  allowing the grass cuttings to fall in the direction of arrow B. When all grass cuttings have been dumped, reversing the grass catcher actuator  23  closes the lower grass catcher  25 . When the grass catcher  12 ,  25  is closed, the extension of the actuator  15  is reversed thus allowing the control mechanism to return to its normal working position as shown in  FIG. 1 .  
         [0024]      FIG. 4  shows an autonomous grass/lawn mower  26  with an aerial  28 , which is used for receiving radio signals used in positioning systems such as GPS, DGPS and Real Time Kinematic GPS. The front bumper  1  is attached to the upper grass catcher  12  and is lifted when the emptying mechanism described before is activated.  
         [0025]      FIG. 5  shows an autonomous grass/lawn mower  26  with an energy wave emitter and detector obstacle detection device  29  fitted to the upper grass catcher  12 . The energy wave emitter and detector obstacle detection device  29  will generate a stop signal for the autonomous grass/lawn mower if an obstacle is detected at a distance equal to the stopping distance of the vehicle.  
         [0026]     In both of these embodiments, the obstacle detecting means is connected to the catcher  12  and is displaced from its normal working position when the emptying mechanism is activated. The emptying mechanism lifts the catcher  12  clear of the vehicle so that the waste material is deposited outside of the range of the obstacle detecting means when the detecting means is in its normal working position.  
         [0027]      FIG. 6  shows an autonomous grass/lawn mower  26  with an energy wave emitter and detector obstacle detection device fitted to the cowling  4 . The energy wave emitter and detector obstacle detection device  29  will generate a stop signal for the autonomous grass/lawn mower if an obstacle is detected at a distance equal to the stopping distance of the vehicle.  
         [0028]      FIG. 7  shows an autonomous grass/lawn mower with a grass catcher  30   a ,  30   b  in an elevated position. The grass catcher  30   a  is in the working position relative to the upper arm  9  and will remain in this position until the mechanism described previously reaches the position shown. The grass catcher  30   a  is rotated about a horizontal pivot  32  using an actuator  31  until the grass catcher position  30   b  is reached. At this point the grass cuttings will fall from the grass catcher  30   b  in the direction indicated by arrow B.  
         [0029]     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.