CN1139201A - Method and apparatus for guiding driverless vehicle - Google Patents

Abstract

A method and apparatus for guiding a driverless vehicle along a path defined by a guide cable carrying a current in a horizontal road surface includes mounting a first coil, having a major coil axis, at +45 degrees relative to the horizontal on said vehicle, mounting a second coil, having a major coil axis, at -45 degrees relative to the horizontal on said vehicle such that the axes of said first and second coils intersect, sensting both the radial and circular field vectors of the electromagnetic field with each coil, comparing the magnitude of the radial vector with the magnitude of the circular vector for each coil whereby the lateral position of the intersection point of the axes of the coils is determined relative to the guide cable to indicate the lateral displacement of the vehicle relative to said path, and using the displacement information in the vehicle steering system.

Description

The method and apparatus of guiding driverless vehicle

The present invention relates to be used for the equipment and the method for coming guiding driverless vehicle along the guide cable that is embedded on the road surface, and more particularly, relate to the use of two magnetic test coils, these two magnetic test coils are set in the vehicle with the X configuration, independently electromagnetic field direction vector and electromagnetic field magnitude-these information are used to the lateral excursion of measuring vehicle with respect to guide cable with the space to detect, so that vehicle is led, thereby make it along guide cable.

On automatic driving vehicle, be provided with vertically disposed coil, be used to detect the electromagnetic field around the guide cable, with along cable guiding driverless vehicle automatically.In known equipment, a coil vertically is provided with, and another coil flatly is provided with.The voltage that induces in coil obtains comparison, and is used to determine the lateral attitude of coil with respect to guide cable.This positional information is handled, and is used to guided vehicle.

The output voltage relevant with these coils with power frequency in the guide cable, guide cable current amplitude, change with angle (being called angle β) from cable to the line between the hub of a spool apart from size, coil turn and the coil main shaft of the radial distance of guide cable, iron-core coil with being directly proportional.

When each coil rotated in the plane perpendicular to the cable that produces magnetic field, it is maximum that its output will reach when iron-core coil is parallel with the magnetic line of force of circumferencial direction.Reach when its output will be vertical with the magnetic line of force at iron-core coil (promptly point to or refer to from line) minimum (zero).Therefore, the relative efficiency of coil changes with the form of the sine function of angle β.

This sin β item, reflected each coil position detected radially with the ratio of toroidal field, and affect and detect output.Therefore, two amplitudes that coil detected poor, be depend on this radially, the respective distance between each coil and cable electric current.Any one change all has remarkable influence to output signal in these factors.In addition, according to angle β, relevant with legacy equipment radially and/or toroidal field information must be rejected, thereby make letter/make an uproar than so not desirable.Another shortcoming of conventional coil configuration is that information that coil provides has only been represented the approximate lateral excursion with respect to guide cable, rather than to the measurement of the distance of lateral excursion.Therefore, can only carry out guiding vehicles along the direction opposite and proofread and correct, and not have accuracy with skew.

One object of the present invention provides a kind of being used for along the equipment of the guiding cable guiding driverless vehicle that is arranged on road surface, and its measuring vehicle is to the lateral excursion of guiding cable.

Another object of the present invention provides a kind of being used for along the equipment that is arranged on the guiding cable guiding driverless vehicle on the road surface, " visual field " of its cable big than in the legacy equipment.

Another object of the present invention, provide a kind of equipment, it comprises vertically disposed coil, these coils are used to provide off-center displacement measurement information, to be arranged on the lateral excursion of the guiding cable on the road surface according to detected distance, come guiding driverless vehicle, it is only definite and irrelevant with all electromagnetic field magnitude components from an electromagnetic field direction vector wherein should to detect lateral excursion.

Another purpose of the present invention, provide a kind of method that is used at a single spatial point detection of electromagnetic fields direction vector, be used to provide an error signal, this error signal has been determined a measurement result, to be used for guiding driverless vehicle on the guiding cable that is arranged on the road surface.

State in realization in purpose and other purposes, this equipment is along the route guidance automatic driving vehicle that is limited by the guiding cable that is arranged on the road surface, wherein this guiding cable is carrying an electric current, and this electric current generates an electromagnetic field in the space of guiding around the cable, and this equipment comprises the amplitude that is used to detect the electromagnetic field around the cable and the detecting device of direction.This detecting device is made up of first and second magnetic test coils that spatially separate, and these coils have main shaft and are installed on the described vehicle with the X coil configuration, thereby this main shaft and sense of current are intersected, and becomes substantially with road surface+/-45 angles of spending.Each magnetic test coil detect set point magnetic field radially with the toroidal field vector, and a processor that links to each other with this first and second magnetic test coil is compared the amplitude of this radial vector with the amplitude of hoop vector, thereby determines the measurement result of the lateral attitude of detecting device with respect to described guiding cable.

Be used for along by the method that is arranged on the route guidance automatic driving vehicle that the lip-deep guiding cable of horizontal road limits a kind of, an electric current generates an electromagnetic field in the space around the guiding cable, and this method may further comprise the steps:

One first coil is installed on described vehicle, and the main shaft of this first coil is from the horizontal by+45 degree;

One second coil is installed on described vehicle, and the main shaft of this second coil is from the horizontal by-45 degree, thereby the axle of first and second coils is intersected along sense of current;

With each coil detection of electromagnetic fields radially with the toroidal field vector;

The amplitude of radial vector is compared with the amplitude of hoop vector, with the lateral attitude of the joining of the axle of setting up coil with respect to the off-center offset information in path; And

This information is sent to one drives assembly, so that this vehicle is driven.

By below in conjunction with accompanying drawing to the detailed description that most preferred embodiment of the present invention carried out, can easily understand above-mentioned and other purposes of the present invention, feature and advantage.

Fig. 1 is the forward sight or the schematic rear view of the automatic driving vehicle on the guiding cable;

Fig. 2 shown according to first and second coils of the present invention, carry the magnetic line of force and the voltage of the electromagnetic field that the guiding cable of alternating current produces, these coils with respect to level become substantially+/-45 degree ground install;

Fig. 3 is a block diagram, shown in the magnetic test coil various voltages and by they convert to output off-center distance measurement signals; And

Fig. 4 is the schematic block diagram of one embodiment of the present of invention.

Referring to Fig. 1, wherein shown the front or rear view of an automatic driving vehicle 10, this automatic driving vehicle 10 moves along the guiding cable 12 that is arranged on the horizontal road surface 14.On vehicle 10, a detecting device 16 is installed, this detecting device 16 is made up of two magnetic test coils 18,20.A coil 18 is spent with 14 one-tenth of road surfaces+45, and another coil 20 then becomes-45 degree.The axle of+45 and-45 expression coils or the angle of its core and road surface 14 or horizontal direction.The axle of coil 16,18 intersects along the direction that electric current flows.Guiding cable 12 carries alternating current, and when this alternating current is not interfered, it produces the electromagnetic field with circular magnetic line of force, this electromagnetic field produces voltage in coil 18 and 20, these voltages can be used to the lateral runout center of measuring vehicle 10 with respect to guiding cable 12, and are used to subsequently along the cable steering vehicle.

Referring now to Fig. 2-4, the mode that automatic driving vehicle 10 obtains guiding is described on cable 12.Dotted line among Fig. 2, the hoop vector in the magnetic field around the representative guiding cable 12.On behalf of near the zone the cable 12, these magnetic lines of force be not subjected to ferromagnetic object and other electric currents to carry the situation (these influences will make the circular cross section of the magnetic line of force distort) of the influence of body.The height h of magnetic test coil 18,20 remains unchanged.

Because how much of coil 18,20 installs and is provided with-wherein each main shaft becomes with level+/-45 degree, the output voltage that each coil produces, be lead the level of cylindricality electromagnetic field of cable 12 and longitudinal component vector with.When detecting device 16 be centered close to the top of cable the time, the level that each coil 18,20 is felt and the amplitude of longitudinal signal equate.Yet the opposite in sign of each signal is because the source that each coil 18,20 is seen is positioned at the not homonymy of their main shaft.When detecting device 16 transversely moved on to the guiding left side of cable 12 or right side, the output of each coil 18,20 changed with the function of error angle θ sum in fore-and-aft plane as its orientation to horizontal plane (+/-45 degree).

The signal of each coil or voltage when its main shaft and guiding cable 12 are perpendicular, reach maximum, and are minimum when its main shaft points to guiding cable.Because these coils 18,20 move on in the plane parallel with cable 12, cut its cylindricality electromagnetic field simultaneously, so their output signal and (β _{Coil 1}Or β _{Coil 2}) sine function change with being directly proportional.

Therefore, by removing the poor of radial vector, obtain the actual location of detecting device 16 or be used for the error position information of feedback loop described below with coil 18,20 detected hoop vector sums.Actual symbol, show that it is by the radial vector sum divided by the difference of hoop vector, but in order to preserve the operation of hardware phase comparator with monitoring " guiding insurance ", the polarity of coil 18,20 is suitably chosen, with convenient detecting device 16 be centered close to cable 12 tops the time, phase phasic difference 180 degree of the output of coil.Therefore, when detecting device 16 be centered close to cable 12 tops the time, vector equates but opposite in sign that the radial vector in the molecule cancels each other out, simultaneously hoop vector addition and being doubled in denominator.Because height h just remains, promptly detecting device 16 rests on the cable 12, so this denominator will can not become zero and make division operation invalid.

Referring to Fig. 2, following formula is suitable for:

Signal=the K1 of coil 1 * sin (β _{Coil 1})

Signal=the K1 of coil 2 * sin (β _{Coil 2})

Therefore:

Distance (+/-Err)=highly * (signal of the signal+coil 1 of coil 2)/(signal of the signal-coil 1 of coil 2)

It below is the mathematical justification of above-mentioned linear measurement formula.

Wherein definition:

Angle from vertical direction along clockwise (CW) direction is for just.

Radius r is defined as the line segment/distance between the center of the center of coil 18,20 and cable 12.

Electric current is defined as the electric current in the lead.

Frequency is defined as the frequency of electric current.

Height h is the fore-and-aft distance of the horizontal plane that can move from cable to coil 18,20 wherein.

Apart from d (+/-) is the horizontal range at the center from cable to coil.

α _{Coil 1}It is the vertical angle that departs from of coil 1 (+45).

α _{Coil 2}It is the vertical angle that departs from of coil 2 (45).

θ is the error angle between radius and the height.

K1 is directly proportional with electric current, frequency and inductance and is inversely proportional to radius

Signal=the K1 of coil 1 * sin (β _{Coil 1}) (formula 1)

Signal=the K1 of coil 2 * sin (β _{Coil 2}) (formula 2)

As shown in Figure 2:

β _{Coil 1}=θ-α _{Coil 1}

And

β _{Coil 2}=θ-α _{Coil 2}

Because as θ=α _{Coil 1}, β _{Coil 1}Become zero and as θ=α _{Coil 2}The time β _{Coil 2}Become zero

Therefore:

Signal=the K1 of coil 1 * sin (θ-α _{Coil 1}) (formula 3)

Signal=the K1 of coil 2 * sin (θ-α _{Coil 2}) (formula 4)

From sin (A-B)=sin (A) cos (B)-cos (A) sin (B), formula 3 and 4 can be unfolded as follows:

Signal=the K1 of coil 1 * (sin θ * cos α _{Coil 1}-

Cos θ * sin α _{Coil 1}) (formula 5)

Signal=the K1 of coil 2 * (sin θ * cos α _{Coil 2}-

Cos θ * sin α _{Coil 2}) (formula 6)

Because according to definition:

α _{Coil 1}=+45 degree, and α _{Coil 2}=-45 degree

We see; Sin α _{Coil 1}=cos α _{Coil 1}=-sin α _{Coil 2}

=cos α _{Coil 2}

And all amplitudes all equal (2 square roots)/2, promptly equal 0.707

Still referring to how much settings shown in Figure 2, can see:

Sin θ=distance/radius=d/r

And

Cos θ=highly/radius=h/r

By following replacement, formula 5 and 6 can access simplification:

Signal=the K1 of coil 1 * (d/r * 0.707-h/r * 0.707)

Signal=the K1 of coil 1 * (d/r * 0.707-h/r * (0.707))

Perhaps, when

During K '=(K1 * 0.707)/r

Signal=the K ' of coil 1 * (d-h)

Signal=the K ' of coil 2 * (d+h)

For the height h with detecting device solve desirable error distance (+/-d), the output of two coils is combined in the following way:

(signal of the signal+coil 1 of coil 2)/(signal of the signal-coil 1 of coil 2)=K ' * ((d+h)+(d-h))/(K ' * ((d+h)-(d-h)))=(d+h+d-h)/(d+h-d+h)=the d/h=distance/highly

Therefore:

Distance (+/-Err)=highly * (signal of the signal+coil 1 of coil 2)/(signal of the signal-coil 1 of coil 2)

To this utilization of separating, the device of driving automatic driving vehicle with known being used to combines, and can implement with block diagram as shown in Figure 3.

Referring to Fig. 3, can see independent add, subtract, removing and take advantage of, all be to obtain this to separate desiredly, and can handle by the analog or digital circuit.Other signal Processing, i.e. filtering, interchange demodulation, A/D conversion can realize easily.

In order to utilize detecting device 16, the output of coil 18,20 must obtain synchronous demodulation, with save symbol information.

Fig. 4 has shown a kind of method of " X coil " detector applies in the control loop of automatic driving vehicle 10 with the block diagram form.

Referring to Fig. 4, an example of above-mentioned " X coil " configuration is vehicle 10 designs, is used for driving on the working depth that is higher than 3 inches of 100 milliamperes of guiding cables, provides+/-3 inches hardware " guiding insurance " width.Yet,, can adopt software described below " guiding insurance " feature, thereby make detecting device 16 can cover the scope of 1 to 6 inch height easily for the higher or lower situation of detecting device height h wherein.Adopt AGC, numeral drive the unit can handle 20 to 400 milliamperes cable electric current, 1 to 6 inch altitude range and+/-12 inches offset scope.

Adopt high Q value filtering device and synchronous demodulator, the nonsynchronous external signal of frequency and phase place is rejected.Yet, can a unaccepted signal, be near identical lead, such as " returning incision " situation in the path.Return incision and will make the electromagnetic field distortion, thereby make the zero point drift of detecting device.This distortion will cause a zero point drift, this zero point drift is directly proportional with the distance of detecting device to each cable, if promptly highly be 3 inches and return the incision be 24 inches, 3/24 of whole outgoing position (when 3 inches height is 3 inches) will drift about zero point, or 3/24 * 3=3/8 inch, and the direction of drift depends on the phase place of " returning incision ".Half place of distance between two cables, when the hoop vector vanishing that produced, each index all descends.10 to 12 inches scope, because near 20 feet the incision of returning, 10 to 12 inches scope, linearity also descends.Owing to these reasons, this current unit in horizontal shift is+/-8 inches places with the output signal calibration of detecting device to+/-gamut.

Therefore, the visual field of detecting device 16 will be increased greatly, and does not lose the directivity on a left side and right side.This has improved the Recovery Process of " departing from wire-control ".In addition, by the vast improvement of linearity, and present wagon detector height is provided with, and all output all becomes+/-8 inches single ratio, thereby provide+/-4 inches the lead that departs from drives and regulates, to deal with the center of " return incision " and/or aligning load.

" visual field " and the linearity of broad provide variable programming " guiding insurance " boundary.It is useful in monitoring " departing from wire-control " that this feature has been proved to be.That inner hardware phase comparator provides is elementary+/-" guiding insurance " output.But this window is not what be for all detecting device height settings.

Dispose by this " X coil ", should+/-the become height h of the coil 18,20 that equals the lead top of " guiding insurance " window, promptly for the detecting device 16 that is positioned at 3 inches places, top, lead center, should " guiding insurance " window will for+/-3 inches, and change+change/-1/2 inch the time+/-1/2 inch in the lead degree of depth.Under the control of a vehicle microcomputer, which will be controlled for this numeral driving software or two " guiding insurance " signals will be activated.

Though described most preferred embodiment of the present invention in detail, those skilled in the art should be understood that various replacement designs and the embodiment within the scope of appended claims.

Claims (11)

1. be used for along by the equipment that is arranged on the route guidance automatic driving vehicle that the lip-deep guiding cable of horizontal road limits, described guiding cable is carried an electric current, thereby has produced an electromagnetic field in this guiding cable space on every side, and described equipment comprises:

Detector means is used to detect the direction and the amplitude of this electromagnetic field;

Described detector means comprises first and second magnetic test coils that are separated from each other, and these magnetic test coils are installed on the described vehicle with the X coil configuration, thereby described main shaft is intersected and becomes substantially+/-45 degree with respect to described road surface;

Each magnetic test coil detect described magnetic field radially with the toroidal field vector; And

With the device that described first and second magnetic test coils link to each other, be used for the amplitude of this radial vector is compared with the amplitude of hoop vector, thereby determine the lateral attitude of described detector means with respect to described guiding cable.

2. according to the equipment of claim 1, wherein said first and second coils have core length and iron core diameter, and the described interval between the wherein said coil equals a core length at least.

3. according to the equipment of claim 1, further comprise an installing plate, this plate has first and second sides, be used for described first magnetic test coil being installed in first side of described installing plate with+45 degree, and with-45 degree described second magnetic test coil is installed on described second side, and wherein said installing plate is fixed on the described vehicle.

4. according to the equipment of claim 2, wherein said comparison means removes detected electromagnetic field radial vector with this hoop vector, thereby the horizontal shift that makes this ratio and described detecting device is directly proportional with the ratio of the height of described detecting device on described cable.

5. according to the equipment of claim 4, further comprise the device that is used for vehicle drive, this device links to each other with described comparison means, is used in response to the output of described comparison means processing described vehicle being driven.

6. according to the equipment of claim 5, wherein said pilot instrument is digital control loop.

7. according to the equipment of claim 5, wherein said pilot instrument is a driving simulation system.

8. be used for along the method for the route guidance automatic driving vehicle that is limited by the guiding cable that is arranged on the road surface, described guiding cable carries electric current, thereby produces an electromagnetic field in the space around the guiding cable, said method comprising the steps of:

One first coil is installed, and it has with the horizontal direction of described vehicle+the 45 coil main shafts of spending;

One second coil is installed, and it has the coil main shaft that becomes-45 degree with the horizontal direction of described vehicle, thereby the described axle of described first and second coils is intersected;

With each coil detect this electromagnetic field radially with the toroidal field vector;

The radial vector amplitude of each coil is compared with the amplitude of hoop vector, thereby the intersection point of the axle of definite described coil is with respect to the lateral attitude of guiding cable, to show the lateral excursion of described vehicle with respect to described path.

9. method according to Claim 8, the described installation steps of wherein said second coil comprise makes described coil at a distance of at least one iron-core coil length.

10. according to the method for claim 9, further comprise described lateral excursion information is sent to a controller to carry out the step of vehicle drive.

11. method according to Claim 8, the lateral attitude of the intersection point of the axle of wherein said coil is determined by following formula:

Distance (+/-Err)=highly * (signal of the signal+coil 1 of coil 2)/(signal of the signal-coil 1 of coil 2)

Wherein:

The horizontal range of distance (+/-)=from cable to hub of a spool

Highly=fore-and-aft distance of the horizontal plane that can move therein from cable to coil.

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