Control apparatus of unmanned autonomous operating vehicle

In an apparatus for controlling an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery for operating lawn mower blades, and magnetic sensors for detecting intensity of a magnetic field of an area wire such that the vehicle is controlled to run about in an operating area defined by the area wire to mow lawn using the blades and to return to a charging device installed on the area wire so as to charge the battery, a distance from the area wire is detected based on the detected intensity of the magnetic field detected by the magnetic sensors, and a different one of returning trajectories defined along the area wire in advance with respect to distances from the area wire is selected, whenever the vehicle is to be returned.

BACKGROUND

1. Technical Field

An embodiment of the invention relates to a control apparatus of an unmanned autonomous operating vehicle, particularly to an apparatus for controlling an operating vehicle to autonomously run about in an operating area to perform an operation using a mounted operating machine.

2. Background Art

Conventionally, there are proposed a variety of unmanned autonomous operating vehicles that autonomously run about in operating areas to perform operations using mounted operating machines (such as lawn-mowing blades), as taught, for example, by International Publication No. WO 2005/074362.

In the reference, a magnetic sensor attached to a front end of an operating vehicle detects the intensity of a magnetic field of an area wire laid along a border of an operating area to recognize the operating area, and a mounted operating machine including lawn-mowing blades and installed with an electric motor is driven to perform the operation in the recognized operating area.

The motor of the vehicle in the technique stated in the reference is supplied with power from a mounted battery. In order to charge the battery, a charging device is disposed on the area wire and when the remaining battery level is decreased, the vehicle is controlled to return to the charging device along the area wire by the aid of the magnetic sensor.

SUMMARY

The vehicle disclosed in the reference is configured to be returned to the charging device disposed on the area wire to charge the battery when the remaining battery level is decreased as mentioned above. Since the vehicle runs on a same trajectory or route whenever it is returned to the charging device, tracks or grooves are formed on the ground along the area wire by wheels of the vehicle and it may degrades the appearance of the operating area of after the operation, disadvantageously.

An object of an embodiment of the invention is therefore to overcome the foregoing drawback by providing a control apparatus of an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery to drive an operating machine to perform an operation, which apparatus can avoid damaging the appearance of the ground of the operating area due to a trajectory in tracks or grooves formed when the vehicle is returned to a charging device to charge the battery.

In order to achieve the object, the embodiment of the invention provides in the first aspect an apparatus for controlling an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery for operating an operating machine, prime movers for driving wheels, and magnetic sensors for detecting intensity of a magnetic field of an area wire, the vehicle being controlled to run about in an operating area defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device installed on the area wire so as to charge the battery, wherein the improvement comprises: an area wire distance detector adapted to detect a distance from the area wire based on the detected intensity of the magnetic field detected by the magnetic sensors; and a returning trajectory selector adapted to select a different one of a plurality of returning trajectories defined along the area wire in advance with respect to distances from the area wire, whenever the vehicle is to be returned to the charging device installed in the operating area to charge the battery.

In order to achieve the object, the embodiment of the invention provides in the second aspect a method for controlling an unmanned autonomous operating vehicle having an electric motor supplied with power from a battery for operating an operating machine, prime movers for driving wheels, and magnetic sensors for detecting intensity of a magnetic field of an area wire, the vehicle being controlled to run about in an operating area defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device installed on the area wire so as to charge the battery, wherein the improvement comprises the steps of: detecting a distance from the area wire based on the detected intensity of the magnetic field detected by the magnetic sensors; and selecting a different one of a plurality of returning trajectories defined along the area wire in advance with respect to distances from the area wire, whenever the vehicle is to be returned to the charging device installed in the operating area to charge the battery.

DESCRIPTION OF EMBODIMENT

A control apparatus of an unmanned autonomous operating vehicle according to an embodiment of the present invention will now be explained with reference to the attached drawings.

FIG. 1is a side view of a control apparatus of an unmanned autonomous operating vehicle according to an embodiment of the invention,FIG. 2is a plan view of the vehicle shown inFIG. 1,FIG. 3is a block diagram showing input and output of devices mounted on the vehicle shown inFIG. 1andFIG. 4is a plan view showing an operating area where the vehicle shown inFIG. 1is to run about.

As shown inFIGS. 1 and 2, symbol10indicates an unmanned autonomous operating vehicle. The vehicle10has a vehicle body12and wheels14. The body12includes a chassis12aand a frame12battached to the chassis12a, while the wheels14include right and left front wheels14aof a relatively small diameter that are fixed on the forepart of the chassis12athrough a stay12a1, and right and left rear wheels14bof a relatively large diameter that are directly attached to the chassis12a.

Blades (rotary blades; operating machine)16for mowing lawn are attached in the center or thereabout of the chassis12a, and an electric motor (hereinafter called the “operating motor”)20is installed above the blades16. The blades16are connected to the operating motor20to be driven and rotated thereby.

The blades16are also connected to a blade height adjustment mechanism22to be manually manipulated by an operator (user). The blade height adjustment mechanism22is equipped with a screw (not shown) to be manually turned by the operator for adjusting the height of the blades16from a contacting ground GR.

Two electric motors (prime movers; hereinafter called the “running motors”)24are attached to the chassis12aof the vehicle10to the rear of the blades16. The running motors24are connected to the right and left rear wheels14bto operate them so that the rear wheels14bare rotated in the normal (forward running) direction or reverse (backward running) direction independently of each other to make the vehicle10to run on the ground GR. In other words, the front wheels14aserve as the free wheels while the rear wheels14bserve as the driven wheels. The blades16, operating motor20, running motors24, etc., are covered by the frame12b.

A charging unit (including an AC/DC converter)26and battery30are accommodated at the rear of the vehicle10and two charging terminals32are attached at the front of the vehicle10to the frame12bto protrude forward. Each of the terminals32has a contact point32aon a side facing the other contact point32a.

The terminals32are connected to the charging unit26through wiring and the charging unit26is connected to the battery30through wiring. The operating and running motors20,24are connected to the battery30through wiring to be supplied with power therefrom. The wiring is not illustrated inFIGS. 1 and 2.

A front end of the vehicle10is installed with two, i.e., right and left magnetic sensors (magnetism detector)34. The frame12bis attached with a contact sensor36. When the frame12bcomes off from the chassis12aupon having contact with an obstacle and such, the contact sensor36outputs an ON signal.

A housing box is provided in the center or thereabout of the vehicle10to house a board40on which an Electronic Control Unit (ECU; Controller)42including a microcomputer having a CPU, ROM, RAM, etc., is installed. The board40is also installed in the vicinity of the ECU42with a Yaw sensor (angular velocity sensor)44that produces an output or signal indicative of angular velocity (yaw rate) generated about a z-axis in the center of gravity of the vehicle10and with a G sensor (acceleration sensor)46that produces an output or signal indicative of an acceleration G acting on the vehicle10in the X, Y and Z (three-axis) directions.

A wheel speed sensor50is installed near the rear (driven) wheel14bto produce an output or signal representing a wheel speed thereof. A lift sensor52is installed between the chassis12aand frame12bto output an ON signal when the frame12bis lifted from the chassis12aby the operator or the like.

A current/voltage sensor54is installed at the battery30to produce an output or signal indicative of SOC (State Of Charge) of the battery30. The vehicle10is installed with a main switch56and emergency stop switch60to be manipulated by the operator.

The outputs of the foregoing magnetic sensors34, contact sensor36, Yaw sensor44, G sensor46, wheel speed sensor50, lift sensor52, current/voltage sensor54, main switch56and emergency stop switch60are sent to the ECU42.

The upper surface of the frame12bof the vehicle10is widely cut away and a display62is installed therein. The display62is connected to the ECU42to show a mode of the vehicle's status such as an operating mode in response to a command sent from the ECU42.

Next, the explanation will be made on the operating area70where the vehicle10is to run about. As shown inFIG. 4, the operating area70has a substantially-rectangular shape and is defined by an area wire (electric wire)72that is embedded (laid) along a border of land L. A charge ST (station)74is provided on the area wire72. Note that the vehicle10inFIG. 4is exaggerated in size.

The charge ST (charging device)74is disposed with an ST coil76. A magnetic field radiated from the ST coil76forms a charging device detecting area76aof a circle with center at the charge ST74with a radius of about one meter. Thus, the charge ST (charging device)74is disposed with the coil76radiating a magnetic field that forms the charging device detecting area76aaround the charge ST74.

As shown inFIG. 5, the charge ST74has a charging device84connected to a commercial power source80through a socket82, and a charging terminal86that is connected to the charging device84and connectable to the contact points32aof the charging terminals32of the vehicle10through its contact points. The charging terminal86is shown inFIG. 6(the contact points thereof are not illustrated).

The charging device84has an AC/AC converter84a, an Electronic Control Unit (ECU)84bthat includes a microcomputer similarly to the ECU42and controls the operation of the AC/AC converter84a, and a signal generator84cthat supplies alternating current to the area wire72and ST coil76to generate signals.

Alternating current coming from the commercial power source80through the socket82is appropriately stepped down by the AC/AC converter84aof the charging device84and, when the vehicle10is returned and connected to the charge ST74through the charging terminals32and86, the current is sent to the vehicle10to charge the battery30through the charging unit26.

The operation of detecting the operating area70will be explained. Upon power supply from the signal generator84c, a magnetic field is generated around the area wire72. The intensity of the magnetic field varies depending on the entire length of the area wire72and also varies depending on a distance d from the area wire72as shown inFIG. 7.

The intensity of the magnetic field of the area wire72is detected by the magnetic sensors34attached to the vehicle10and sent to the ECU42. Based on the detected values, the ECU42detects a position of the subject vehicle (autonomous operating vehicle10) with respect to the area wire72(i.e., whether the subject vehicle is positioned inside or outside the operating area70) and the distance of the subject vehicle from the area wire72(i.e., from the border of the operating area70).

More specifically, as shown inFIG. 7, when the subject vehicle is moved from the inside of the operating area70to the outside thereof in a direction indicated by an arrow a, as the distance from the area wire72is reduced (as the subject vehicle is moved closer to the area wire72), the intensity of the magnetic field is gradually increased on a positive side and afterward, decreased. When the subject vehicle is positioned on the area wire72, the intensity becomes zero. Subsequently, when the distance from the area wire72is again increased, the intensity exhibits the similar characteristics on a negative side. Also when the subject vehicle is moved from the inside of the operating area70to the outside thereof in a direction indicated by an arrow b, the characteristics similar to the above pattern are exhibited.

The operation of the vehicle10will be explained. The height of the blades16is manually adjusted by the operator through the blade height adjustment mechanism22in accordance with a growing condition of the lawn in the operating area70. When the main switch56is switched on so that the ON signal is outputted, the ECU42starts to be operated and enters the operating mode to mow the lawn.

In the operating mode, the ECU42calculates a power supply control value with which a vehicle speed detected from the output of the wheel speed sensor50becomes a predetermined value and supplies the calculated value to the running motors24through a driver24ato make the vehicle10run about. Further, the ECU42calculates a power supply control value with which rotational speeds of the blades16become a predetermined value and supplies the calculated value to the operating motor20through a driver20ato operate the blades16to perform the operation.

To be more specific, in the operating mode, the ECU42makes the vehicle10run about randomly (or in accordance with an operation pattern) to perform the operation within the operating area70. When determining that the vehicle10has moved out of the operating area70based on the outputs of the magnetic sensors34, the ECU42changes a running direction detected based on the output of the Yaw sensor44by a predetermined angle so that the vehicle10comes back to the inside of the operating area70.

Since the right and left rear (driven) wheels14bare configured so that they are driven by the running motors24to rotate in the normal and reverse directions independently or separately from each other, when the motors24are rotated in the normal direction at the same speed, the vehicle10runs straight, whilst when they are rotated in the normal direction at different speeds, the vehicle10is turned toward a side of lower rotational speed. When one of the motors24is rotated in the normal direction and the other is rotated in the reverse direction, since the rear wheels14bare rotated in the same direction as the associated motor's rotation, the vehicle10is turned at the same position (which is so-called pivot turn).

Thus, in the operating mode, the ECU42makes the vehicle10run about within the operating area70while changing the running direction thereof randomly whenever the vehicle10reaches the area wire72, and drives the blades16to perform the operation.

Further, in the operating mode, the ECU42monitors the SOC of the battery30based on the output of the current/voltage sensor54and when the remaining battery level is decreased to a predetermined level, transitions to a return mode in which the vehicle10is returned to the charge ST74to charge the battery30by the charging device84.

In the operating mode and return mode, when any of the contact sensor36, lift sensor52and emergency stop switch60produces the ON signal, the ECU42stops the operating and running motors20,24to stop the operation and running of the vehicle10.

FIG. 8is a flowchart showing the operation of the ECU42in the return mode.

First, trajectories (returning trajectories) to be used in the processes of theFIG. 8flowchart are explained with reference toFIGS. 4 and 7. In the embodiment, as illustrated, based on the distance from the area wire72(more exactly, in decreasing order of the distance), a plurality of, e.g., four trajectories 1, 2, 3, 4 set (defined) in advance and stored in the ROM of the ECU42.

To be more specific, as shown inFIGS. 4 and 7, the set trajectories 1, 2, 3, 4 are respectively linked with four values of intensities obtained by dividing into quarters an intensity of the magnetic field of a certain distance range d, in increasing order of the intensity (i.e., in ascending order of the corresponding distance). The set trajectory 4 away from the area wire72the most is arranged so that it is, for example, one meter away from the area wire72with taking the radius of the charging device detecting area76ainto account.

In the processes in theFIG. 8flowchart, the vehicle10is controlled to follow different one of the set trajectories whenever it is to be returned to the charge ST74. Specifically, it is configured to select one of the set trajectories in order of 4, 1, 2, 3, 4, . . . , and the selecting operation is carried out by referring to a counter prepared in the RAM and retrieving a suitable one from data in the ROM or through other method.

More specifically, it is configured so that the set trajectories 1, 2, 3, 4 are positioned away from the area wire72by different distances and one of the set trajectories is selected such that the distance from the area wire72increases (than one time before) whenever the vehicle10is returned to the charge ST74.

Further, it is configured so that an entering direction of the vehicle10to the charge ST74is alternately changed between a CW (Clockwise) and CCW (Counterclockwise), as viewed from above of the operating area70(shown inFIG. 4), whenever the vehicle10is to be returned. It is carried out by setting an appropriate flag in the RAM of the ECU42.

Based on the above configuration, the explanation on theFIG. 8flowchart will be made. This program begins when the vehicle10is to be returned to charge the battery30. First, the running motors24are operated to make the vehicle10run straight (S10), the area wire72is detected based on the outputs of the magnetic sensors34, and the vehicle10is moved out of the operating area70and stopped (S12).

Next, it is determined whether the entering direction of the vehicle10when it is returned to the charge ST74is set as the CW (S14). When the result in S14is affirmative, the vehicle10is restarted to run while turning (if necessary) so that it can enter the charge ST74in clockwise (CW) direction (S16), while when the result is negative, the vehicle10is turned (if necessary) so that it can enter the charge ST74in counterclockwise (CCW) direction (S18) and the above process is repeated until it is confirmed that the vehicle10has come inside the operating area70(S20). Then, the entering direction is changed between the CW and CCW for the next returning operation (S22).

Subsequently, the intensity of the magnetic field of the area wire72is detected based on the outputs of the magnetic sensors34(S24) and based on the detected intensity, the operation of the running motors24are controlled to make the vehicle10follow one of the set trajectories along the area wire72(S26).

Specifically, based on the outputs of the magnetic sensors34, the ECU42controls amounts of power to be supplied to the running motors24using a feedback control law such as a proportional term so as to make the vehicle10follow one of the set trajectories 1 to 4 along the area wire72.

More specifically, the ECU42detects a difference (error) between a desired magnetic field intensity expected with a selected one of the set trajectories and the actual magnetic field intensity detected by the magnetic sensors34and calculates the power supply control values to be sent to the running motors24using the proportional term of the feedback control so that the detected difference decreases. That is, based on the outputs of the magnetic sensors34, the ECU42controls amounts of power to be supplied to the running motors24using a feedback control law such as a proportional term so that a front portion of the vehicle10is slightly shaken right and left to be positioned inside and outside the operating area70alternately, thereby controlling the vehicle10to run on or along the area wire72.

In other words, the ECU42detects the distance of the vehicle10from the area wire72based on the detected intensity of the magnetic field, calculates a difference between the detected distance and a defined distance of the selected one of the set trajectories, and calculates the power supply control values to be sent to the running motors24using the feedback control law so that the calculated difference is decreased.

Next, it is determined whether the charge ST74, i.e., the charging device detecting area76ais detected by monitoring a low intensity magnetic field generated from the ST coil76using the magnetic sensors34and comparing it with an appropriate threshold value (S28). Whenever the result in S28is negative, the program returns to S24to repeat the foregoing process.

When the result in S28is affirmative, the ECU42detects the area wire72by turning for example the vehicle10and controls the vehicle10to run along the area wire72while decreasing the running speed to enter the charge ST74(in the CW or CCW direction), whereby the charging terminals32of the vehicle10are connected to the charging terminal86to charge the battery30(S30).

Next, the charged vehicle10is back to the operation and runs about randomly in the operating area70and the blades16are driven by the operating motor20to mow the lawn (S32). It is determined whether the remaining battery level of the battery30is decreased (i.e., becomes equal to or less than the predetermined level) (S34) and until the remaining battery level is determined to have been decreased, the program repeatedly returns to S32to continue the mowing operation.

When the remaining battery level is determined to have been decreased in S34, the vehicle10is returned to the charge ST74. As explained in the foregoing, since one of the set trajectories (returning trajectories) is selected in order of 4, 1, 2, 3, 4, . . . , it is determined whether the currently-selected set trajectory is 4 (S36) and when the result is affirmative, the set trajectory 1 is selected (S38).

When the result in S36is negative, the number of the set trajectory is incremented by one (S40). For instance, in the case where the currently-selected set trajectory is 2, it leads to the equation of 2+1=3 so that the set trajectory 3 is selected. Subsequently, the program returns to S10.

Note that, when (it is determined that) the vehicle10has been moved out of the operating area70during running along the set trajectory 3 for example, the ECU42determines that the set trajectory the vehicle10should go back is the set trajectory 2 positioned on the inner side of the set trajectory 3. Or, when (it is determined that) the vehicle10has been moved out during running along the set trajectory 2, the ECU42determines that the set trajectory the vehicle10should go back is the set trajectory 1 positioned on the inner side of the set trajectory 2.

Thus, since it is configured so that the different trajectory is selected whenever the vehicle10is returned, it becomes possible to prevent tracks or grooves from being formed on the area wire72by wheels14and therefore, avoid damaging the appearance of the operating area70of after the mowing operation. Further, it becomes possible to reliably run about the vehicle10within the operating area70.

As stated above, the embodiment is configured to have an apparatus (and method) for controlling an unmanned autonomous operating vehicle (10) having an electric motor (20) supplied with power from a battery (30) for operating an operating machine (16), prime movers (24) for driving wheels (14), and magnetic sensors (34) for detecting intensity of a magnetic field of an area wire (72), the vehicle being controlled to run about in an operating area (70) defined by the area wire through wheels driven by the prime movers to perform an operation using the operating machine and to return to a charging device (charge ST74, charging device84) installed on the area wire so as to charge the battery, characterized in that: an area wire distance detector (42, S10-S24) adapted to detect a distance from the area wire based on the detected intensity of the magnetic field detected by the magnetic sensors; and a returning trajectory selector (42, S28-S40) adapted to select a different one of a plurality of returning trajectories defined along the area wire in advance with respect to distances from the area wire, whenever the vehicle is to be returned to the charging device installed in the operating area to charge the battery.

With this, since the trajectory to follow is changed every time the remaining battery level is decreased and the vehicle10is returned to the charging device84, it becomes possible to prevent tracks or grooves from being formed on the area wire72by wheels14and therefore, avoid damaging the appearance of the operating area70. Further, since it suffices to modify only the control and another device is not necessary, the structure can be simple.

In the apparatus (and method), the returning trajectories are set to be different from distances away from the area wire and one of the returning trajectories is selected such that the distance from the area wire increases whenever the vehicle is to be returned (S36-S40). With this, in addition to the above effects, it becomes possible to change the trajectory to follow more efficiently.

In the apparatus (and method), the returning trajectory selector changes an entering direction of the vehicle to the charging device whenever the vehicle is to be returned. With this, in addition to the above effects, it becomes possible to change the trajectory to follow more efficiently.

In the apparatus (and method), the charging device is disposed with a coil (ST coil76) radiating a magnetic field that forms a charging device detecting area76aaround the charging device. With this, it becomes possible to detect the charging device more easily.

In the apparatus (and method), the returning trajectory selector selects one of the trajectories positioned on the inner side when the vehicle has been moved out of the operating area during returning to the charging device. With this, in addition to the above effects, it becomes possible to change the trajectory to follow more efficiently.

In the apparatus (and method), the prime movers (24) comprise electric motors to be supplied with power from the battery. With this, in addition to the above effects, it becomes possible to reduce the noise compared to a case that an engine is employed.

In the apparatus (and method), the operating machine (16) comprises a lawn mower. With this, in addition to the above effects, in the mowing operation in which the operating area70is required to have the good appearance after the operation, it becomes possible to avoid damaging the appearance and also avoid needlessly damaging the lawn.

It should be noted that, in the foregoing, although the electric motor is applied as the prime mover, it may be an internal combustion engine or a hybrid of an engine and electric motor.

It should also be noted that, although the lawn-mowing blades are exemplified as the operating machine, but it should not be limited thereto and any machine can be applied if it is used for maintaining the appearance of the operating area.

Japanese Patent Application No. 2012-027634, filed on Feb. 10, 2012 is incorporated by reference herein in its entirety.

While the invention has thus been shown and described with reference to specific embodiments, it should be noted that the invention is in no way limited to the details of the described arrangements; changes and modifications may be made without departing from the scope of the appended claims.