RU2136035C1 - Method and device for vehicle control - Google Patents

Abstract

FIELD: direction of vehicle motion through electric cable laid on (under) road surface. SUBSTANCE: two detecting coils shifted relative to each other and having an X-configuration with the axes positioned at an angle of 1 to 45 deg. relative to the road surface are installed on the vehicle. Each coil reads out both the radial and circular vectors of magnetic field, whose comparison provides for determination of the value of vehicle shift relative to the control cable. EFFECT: increased "field of vision" relative to cable, measurement of the lateral shift of vehicle proceeding from the vector of electromagnetic field direction; facilitated procedure. 9 cl, 4 dwg

Description

 The present invention relates to a method and device for guiding a vehicle without a driver along a guide cable hidden under the road surface, and more particularly, to using two detection coils placed in accordance with the X configuration on a vehicle to read the direction vector of the electromagnetic field independent of spatial and electromagnetic field values, and this information is used to measure the lateral displacement of the vehicle. guide cable to control the vehicle so as to track the guide cable.

On a vehicle without a driver, perpendicularly arranged coils are installed, which are used to detect the electromagnetic field surrounding the guide cable, to automatically guide the vehicle without a driver along the guide cable. In the known device, usually one of the coils is located vertically and the other coil is horizontal, or they can be located at an angle of 45 ^o to the road surface (see application UK N 1092685, IPC G 05 D 1/02, 1967). The voltages induced in the coils are compared and used to determine the lateral location of the coils relative to the guide cable. This location information is processed and used to drive a vehicle.

 The voltage at the output of these coils varies in proportion to the current frequency in the guide cable, the current in the guide cable, the radial distance from the guide cable, the size of the coil core, the number of turns of the coil winding and the angle between the main axis of the coil and the line from the cable to the center of the coil, which called angle beta.

 Since each coil rotates in a plane perpendicular to the cable generating the electromagnetic field, its output signal becomes maximum when the core of the coil is parallel to the circular lines of magnetic flux. The output signal of the coil becomes minimal (zero) when the core of the coil is perpendicular to the flow, i.e. directed towards or away from the winding. Thus, the coil signal changes in accordance with the sine of the beta angle.

 The term sin (beta) reflects the ratio of the radial field to the circular field, which are measured in each position of the coil and affect the output signal of the sensing element. Therefore, the difference in the values measured by the two coils depends on the radius, the corresponding distances between the coils and the cable current. A change in any of these factors leads to significant changes in the output signal. Additionally, depending on the angle of beta, some radial and / or circular field information associated with conventional equipment, which is obtained as a result of a less than ideal signal-to-noise ratio, should be discarded. Another disadvantage of the known mutual arrangements of the coils is that the information provided by the coils indicates only an approximate lateral displacement relative to the guide cable and does not constitute a measurement of the lateral displacement distance. Therefore, the correction of the vehicle control can be made only in the direction opposite to the offset, and inaccurate.

 An object of the present invention is to provide a method and device for guiding a vehicle without a driver along a guide cable located below the road surface, which allows measuring the lateral deviation of the vehicle from the guide cable.

 Another objective of the present invention is to provide a device for guiding a vehicle without a driver along a guide cable located below the surface of the road having an increased "field of view" relative to the cable compared to known devices.

 Another objective of the present invention is to provide a device that allows you to obtain offset information from the center necessary for driving a vehicle without a driver, based on the measured lateral displacement relative to the guide cable located under the road surface, and the measured lateral displacement is determined solely on the basis of the direction vector of the electromagnetic field and does not depend on all components of the magnitude of the total electromagnetic field.

 A method for guiding a vehicle without a driver along a path defined by a guide cable located under a horizontal road surface, wherein a current flows through the guide cable, creating an electromagnetic field in the space surrounding the guide cable, according to the present invention comprises the steps of: mounting a first coil having a main axis located at an angle of +45 degrees relative to the horizontal of the specified vehicle; the installation of a second coil having a main axis located at an angle of -45 degrees relative to the horizontal of the specified vehicle, and the axis of the first and second coils intersect; reading both radial and circular vectors of the electromagnetic field of each coil; comparing the magnitude of the radial vector with the magnitude of the circular vector to establish the lateral position of the point of intersection of the axes of the coils relative to the cable (lateral displacement of the vehicle); transmitting this information to a control unit for driving a vehicle.

 A device for guiding a vehicle without a driver along a path defined by a guide cable located under the road surface, and a current flowing through the guide cable, creating an electromagnetic field in the space surrounding the guide cable, contains a sensing element for detecting the direction and magnitude of the electromagnetic field surrounding the cable. The sensing element is formed by the first and second detection coils offset from each other, the main axes, in accordance with this invention, which are located in accordance with the X-configuration on the specified vehicle so that the main axes intersect and are oriented at an angle of +45 and -45 degrees relative to the road surface. Each detecting coil reads vectors of both radial and circular magnetic fields at a given point. Means are provided associated with the first and second detecting coils that compare the magnitude of the radial vector with the magnitude of the circular vector, whereby the lateral position (offset) of the sensing element relative to the guide cable is measured. These comparison tools are made by dividing the read radial vector of the electromagnetic field into a circular vector. The resulting ratio is proportional to the horizontal displacement of the sensing element (detecting coils) and is a control signal supplied to the vehicle controls. These controls may be a digital or analog control system.

 Detecting coils can be mounted on vehicles using a circuit board, and it is advisable to fix one of them on one side of the board, and the other on the opposite. Detecting coils should be placed with a gap relative to each other at least by the size of its length so that the field measured by one coil is not disturbed by the other coil.

 The above features and advantages of the present invention will become readily apparent from the following detailed description of a preferred embodiment of the invention, given with reference to the accompanying drawings.

 In FIG. 1 is a schematic front or rear view of a vehicle without a driver that can be guided along a guide cable located under the road surface; in FIG. 2 is a diagram showing the first and second coils installed in accordance with the present invention at an angle of +/- 45 degrees relative to the horizontal, as well as the lines of the electromagnetic field and the voltage vectors in the electromagnetic field created by the guide cable through which the alternating current flows; in FIG. 3 is a block diagram showing various voltages in the detection coils and their conversion to an output signal for measuring the distance of the offset from the center; in FIG. 4 is a block diagram of one embodiment of the invention.

 Turning now to the consideration of FIG. 1, which shows a front or rear view of a vehicle 10 without a driver, which can follow a guide cable 12 located in the (under) horizontal road surface 14. A sensing element 16 is installed on the vehicle 10, which comprises two detection coils 18, 20 One of the coils 18 is installed at an angle of +45 degrees relative to the road surface 14, and the other coil 20 is installed at an angle of -45 degrees. The terms +45 and -45 degrees refer to the angle of the axis of the coil or its core relative to the surface STI road 14 or relative to the horizontal. The axis of the coils 16, 18 intersect in the direction of current flow. An alternating current flows through the guide cable 12, which, if there is no disturbance, creates an electromagnetic field with circular magnetic lines that induce (generate) voltage coils 18 and 20, which can be used to measure the lateral displacement of the center of the vehicle 10 relative to the guide cable 12, and then driving the vehicle to guide it along the cable.

 Now with reference to FIG. 2-4 will be described how the direction of the vehicle without a driver is carried out along cable 12. The dashed lines in FIG. 2 show the circular vectors of the magnetic field surrounding the guide cable 12. These (power) field lines are intended to represent a case in which there are no ferromagnetic objects or other current carriers near the cable 12 that could disrupt the cross-section of the field lines. The vertical position or height h of the detection coils 18, 20 remains constant.

 As a result of the installation (installation) geometry of the coils 18, 20, when each of the main axes is located at an angle of +/- 45 degrees relative to the horizontal, each coil creates an output voltage, which is the vector sum of the vertical and horizontal portions (components) of the cylindrical electromagnetic field of the guide cable 12. When the sensing element 16 is centered over the cable, then each coil 18, 20 has the same horizontal and vertical signal values. However, the signs of the signals are opposite, since each coil 18, 20 "sees" the source (signal) from different sides of its main axis. When the sensing element 16 is laterally shifted left or right with respect to the guide cable 12, the output signal of each coil 18, 20 changes as a function of the sum of its orientation to the horizontal plane (+/- 45 degrees) and the theta angle in the vertical plane.

 The signal or voltage of each of the coils is maximum when the main axis is perpendicular to the guide cable 12, and minimal (equal to zero) when its main axis is directed to the guide cable (points to it). Since these coils 18, 20 move in a plane parallel to the cable 12, while crossing the lines of force of its cylindrical electromagnetic field, their output signals are proportional to SIN (Beta winding 1 or 2).

 Accordingly, the true position of the sensing element 16 or the position error information for the feedback circuit described later can be found by dividing the difference of the radial vectors by the sum of the circular vectors read by the coils 18, 20. The true sign is determined by the fact that the sum of the radial vectors is divided by the difference of the circular vectors, however, for the phase comparator to operate with the “safe control” control, the polarity of the coils 18, 20 is chosen so that when the sensitive element is mounted (centered) above the cable m 12, the output signal is shifted in phase coils (misphased) by 180 degrees. Therefore, when the sensing element 16 is installed above the cable 12, the vectors will be equal, but will have the opposite sign, while the radial vectors in the numerator are destroyed, while the circular vectors are doubled in the denominator. Since the height h remains positive, i.e. the sensing element 16 is located above the cable 12, the denominator never reaches zero and does not cause the uncertainty of the division operation.

In accordance with figure 2, you can write the following equations:
Winding signal 1 = K1 • SIN (Beta winding 1)
Winding signal 2 = K2 • SIN (Beta winding 2)
Therefore:
Distance (+/- error) = Height • (Winding signal 2 + Winding signal 1) / (Winding signal 2 - Winding signal 1).

 The following is a mathematical proof of the reduced linear measurement equation.

A-priory:
The clockwise angles relative to the vertical are positive.

 The radius r is defined as the distance / line between the center of the coils 18, 20 and the center of the cable 12.

 A current is defined as an electric current in a winding.

 Frequency is defined as current frequency.

 The height h is the vertical distance from the cable to the horizontal plane in which the coils 18, 20 can move.

 The distance d (+/-) is the horizontal distance from the cable to the center of the coils.

 The angle of alpha coil 1 is the angle of offset from the vertical of coil 1 (+45).

 The angle of alpha coil 2 is the angle of offset from the vertical of coil 2 (-45).

 Theta is the angle of error between radius and height.

and
K1 is proportional to current, frequency and inductance and inversely proportional to radius.

Winding signal 1 = K1 • SIN (Beta winding 1) (equation 1)
Winding signal 2 = K1 • SIN (Beta winding 2) (equation 2).

From FIG. 2 can be seen:
Beta winding 1 = Theta Alpha winding 1
and
Beta winding 2 = Theta Alpha winding 2,
in this case, when Theta = Alpha winding 1, Beta winding 1 approaches zero, and when Theta = Alpha winding 2, Beta winding 2 approaches zero.

Therefore:
Winding signal 1 = K1 • SIN (Theta Alpha winding 1) (equation 3).

 Winding signal 2 = K2 • SIN (Theta Alpha winding 2) (equation 4).

Using trigonometric identity:
SIN (AB) = SIN (A) • COS (B) -COS (A) • SIN (B)
equations 3 and 4 can be represented as follows:
Signal winding 1 = K1 • (SIN (Theta) • COS (Alpha winding 1) - COS (Theta) • SIN (Alpha Winding 1)
(equation 5)
Signal winding 2 = K1 • (SIN (Theta) • COS (Alpha winding 2) - COS (Theta) • SIN (Alpha Winding 2)
(equation 6)
and since by definition:
Alpha winding 1 = +45 degrees and Alpha winding 2 = - 45 degrees, then
SIN (Alpha winding 1) = COS (Alpha winding 1) = SIN (Alpha winding 2) = COS (Alpha winding 2),
for all values equal to (Square root of 2) / 2, which is approximately equal to 0.707 ...

From the geometry shown in FIG. 2, it can also be seen that:
SIN (Theta) = Distance / Radius = d / r
and
COS (Theta) = Height / Radius = h / r.

Equations 5 and 6 can now be simplified by replacing:
Winding Signal 1 = K1 • (d / h • 0.707 - h / r • 0.707)
Winding Signal 2 = K1 • (d / h • 0.707 - h / r • -0.707)
or when
Winding signal 1 = K '• (dh) K' = (K1 • 0.707 / r
Winding signal 2 = K '• (d + h)
To find the desired error of the distance (position) (+/- d) relative to the height (h) of the sensing element, the output signals of the windings must be combined as follows:
(Signal winding 2 + Signal winding 1) / (Signal winding 2 - Signal winding =
[K '• ((d + h) + (dh))] / [K' • ((d + h) - (dh))] = [K '• d + h + dh] / [K' • d + h - dh] = 2d / 2h = d / h = Distance / Height.

Therefore:
Distance (+/- error) = Height • (Winding signal 2 + Winding signal 1) / (Winding signal 2 - Winding signal 1).

 This expression can be implemented using a combination of known driverless vehicle control devices, as shown in the block diagram of FIG. 3.

 From consideration of FIG. 3, it can be seen that the implementation of this expression requires operations of simple addition, subtraction, multiplication and division, which can be done by analog or digital electronics. Additional matching operations on the level and shape of the signal, i.e. filtering, analog-to-digital demodulation, and analog-to-digital conversions can also be easily performed.

 To use the sensing element 16 in order to preserve the sign of information, the output signals of the coils 18, 20 must be synchronously demodulated.

 In FIG. 4, a flowchart illustrates a method for incorporating a sensing element 16 with an X-configuration of coils into a control system of a vehicle 10 without a driver.

 In FIG. Figure 4 shows an example of the previously described X-configuration of coils for a vehicle 10 controlled at a working height of 3 inches above a 100-milliampere guide cable providing a +/- 3 inch "safe control" instrument width. However, for cases where the height of the sensor is higher or lower, the “safe control” software feature described below can be used so that the sensor 16 can span a range of heights from 1 to 6 inches. When using the AGC, the digital control unit can operate in the range of cable currents from 20 to 400 mA, in the range of heights from 1 to 6 inches and in the range of horizontal displacement +/- 12 inches.

 When using high-pass Q filters and synchronous demodulators, all extraneous signals that are not synchronous in frequency and phase are cut off. However, one signal that is not clipped is the “back cut” signal from the adjacent cable. This back-cut signal can distort the electromagnetic field, shifting the zero level of the sensing element. This distortion causes a zero shift, which is directly proportional to the distance of the sensor to each cable, that is, if the height is 3 inches and the back cut is 24 inches, then zero will be shifted by 3/24 of a single output position (3 inches multiplied by a height of 3 inches), or 3/24 • 3 = 3/8 inches, and the direction of the zero shift depends on the phase of the “back cut”. At half the distance between the two cables, any signal is read as the resulting circular vector, while the division result tends to zero. Linearity also falls in the range of 10 to 12 inches as a result of a “back cut” that is closer than 20 feet. For these reasons, the output of the sensor is set to +/- full scale at + \ - 8 inches of horizontal movement.

 Accordingly, the field of view of the sensing element 16 is significantly increased without loss of port / starboard directions. This improves the re-capture procedure of the “wireless maneuver”. With significantly improved linearity and providing currents at the height of the vehicle’s sensing element, all output signals have the same ratio of +/- 8 inches, which allows for wireless control adjustments of +/- 4 inches to account for the “back cut” and / or for alignment (vehicle ) in the loaded state.

 Both a wider "field of view" and good linearity ensure the variability of the programmed "safe control" limits. This feature turned out to be very useful in controlling the “wireless maneuver”, since the technical requirements of ANSI (American National Standards Institute) allow a +/- 6 inch window for such operations. Internal hardware phase comparators provide the primary “safe control" output signal. However, this window cannot be set to +/- 3 inches for all sensory heights.

 With the X-configuration of the coils +/-, the “safe control” window becomes equal to the height h of the coils 18, 20 above the wire (guide cable), that is, for the sensitive element 16 installed 3 inches above the wire, the “safe control” window will be +/- 3 inches and can change by +/- 1/2 inches if the wire depth changes by +/- 1/2 inches. Under the control of the on-board microprocessor, digital control software provides one or two active "safe control" signals.

 Although the preferred embodiment of the invention has been described in detail, those skilled in the art will find various alternative options and solutions for carrying out the invention, which is defined by the following patent claims.

Claims (9)

 1. A method of automatically controlling a vehicle along a path defined by a guide cable located on a road surface, in which a current is transmitted through said guide cable to create an electromagnetic field in the space surrounding the guide cable, including installing detection coils sensing said electromagnetic field on the vehicle characterized in that the first coil is installed having a main axis located at an angle of +45 degrees relative to the horizontal vehicle, and a second coil having a main axis located at an angle of -45 degrees relative to the horizontal of the vehicle, and the axes of the first and second coils intersect, read both the radial and circular vectors of the electromagnetic field of each coil and compare the magnitude of the radial vector with the magnitude of the circular the vector of each of the coils to establish the lateral position of the point of intersection of the axes of these coils relative to the guide cable to determine the lateral displacement of the transport redstva on the way, the information of which is transmitted to the means for driving the vehicle.  2. The method according to claim 1, characterized in that the installation of the coils is carried out with a spatial displacement of them relative to each other by at least one length of the coil.  3. The method according to claim 1, characterized in that the lateral position of the point of intersection of the axes of the indicated coils is determined by the ratio: distance (+/- error) = height • (winding signal 2 + winding signal 1) / (winding signal 2 - winding signal 1 ), in which: distance (+/-) = the horizontal distance from the cable to the point of intersection of the axes of the coils; height = the vertical distance from the cable to the horizontal plane in which the coils can move.  4. A device for automatically controlling a vehicle along a path defined by a guide cable located below the road surface, through which an electric current is passed, creating an electromagnetic field in the space surrounding the guide cable, containing a sensing element for reading the direction and magnitude of the electromagnetic field, containing the first and the second detecting coils offset from each other, means for comparing signals from the coils and means for controlling the transport a device, characterized in that the detection coils are mounted on the vehicle in accordance with the X-configuration so that their main axes intersect from each other and are located at an angle of +45 degrees and the other at an angle of -45 degrees relative to the horizontal, each the detecting coil reads both the radial and circular vectors of the magnetic field, and the means of comparison associated with the indicated first and second detecting coils are made comparing the magnitude of the radial vector with the magnitude circular vector to thereby determine the lateral displacement of the sensing element relative to the guide cable.  5. The device according to claim 4, characterized in that the first and second detecting coils are offset from each other by at least the length of the coils.  6. The device according to claim 5, characterized in that it contains a mounting plate for mounting the first detecting coil on one side of the board and the second detecting coil on its second side, and the specified mounting plate is mounted on the vehicle.  7. The device according to claim 4, characterized in that the means of comparison are made dividing the read radial vector of the electromagnetic field into a circular vector, and the resulting ratio is proportional to the horizontal displacement of the sensor divided by the height of the specified sensitive element above the specified cable.  8. The device according to p. 4, characterized in that the means for controlling the vehicle are a digital control system.  9. The device according to p. 4, characterized in that the means for controlling the vehicle are an analog control system.

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