JP2002182748A - Steering controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a steering controller for stably conrolling the steering of an automatic travel vehicle outdoors. SOLUTION: It is effective that a geomagnetic sensor 1 is used as a direction detecting means outdoors. The erroneous detection of the geomagnetic sensor 1 due to the voltage fluctuation of power 5 becomes a problem. The operation voltage of the geomagnetic sensor 1 is monitored by a voltage fluctuation detection part 304. While voltage fluctuation occurs, a command reset part 305 deletes an erroneous detection direction signal and keeps the steering angle of a vehicle 13 to zero degree instead. Actuator driving quantity for maintaining the vehicle to a travel state just before the occurrence of voltage fluctuation is outputted to an actuator driving part 303 and steering control is continued. Thus, lateral slip in a travel direction at the time of an erroneous detection of the correction is prevented and steering control is stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is mounted on a vehicle which automatically drives in a target direction by controlling an actuator in accordance with an actuator drive signal given to an actuator control means and driving a steering mechanism by the actuator. To a steering control device. As an application field of the present invention, a steering control device for an automatic traveling vehicle using a direction sensor, for example, a steering control for an agricultural tractor that performs unmanned cultivated land maintenance and rice planting work and an automatic guided vehicle that transports building materials at a construction site. And the like.

[0002]

2. Description of the Related Art A direction detection technology is a major problem in automatic driving control technology, and the use of a direction sensor is currently the mainstream from the viewpoint of small size, light weight and low cost. In particular, the geomagnetic sensor requires a small power consumption for driving because of its small size among the orientation sensors. Therefore, it can be said that the device is suitable for mounting on an autonomous vehicle that operates only by its own power supply, and is suitable for azimuth detection in the outdoors where it is difficult to specify the azimuth of the vehicle as compared to indoors. That is, when a color vision sensor or a sound wave sensor is used as a direction sensor, it is necessary to set a specific mark or an object in advance, and disturbance such as weather or noise may cause a difference in target recognition. This is because the terrestrial magnetism sensor has an advantage that the azimuth can be recognized irrespective of the above-mentioned target object and disturbance because the terrestrial magnetism is an absolute value to be detected.

An example of a conventional steering control device will be described with reference to FIGS. FIG. 3 is a block diagram illustrating a configuration of an automatic traveling device including a conventional steering control device, and FIG. 4 is a diagram illustrating a relationship between various elements in the automatic traveling device. In FIG. 3, the steering control device includes a geomagnetic sensor 1 that detects the direction of the vehicle using electric power supplied from a power supply 5, an AD converter 2 that converts a detection value of the sensor 1 into a digital signal, and an output of the AD converter 2. A CPU 3 for arithmetically converting a digital signal into an actuator drive amount and transmitting the same, a DA conversion circuit 7 for converting the drive amount into an analog signal, and controlling an opening amount of the steering control valve 9 by an analog signal output from the DA converter circuit 7. It is composed of an actuator control circuit 8. The controlled object of the automatic traveling vehicle controlled by the steering control device is a wheel 13, a steering mechanism 12 for determining a steering angle of the wheel 13, a hydraulic actuator 10 for driving the steering mechanism 12, and a drive for the hydraulic actuator 10. Steering control valve 9 for controlling the amount and hydraulic source 11
And a steering angle sensor 4 attached to the steering mechanism 12. Here, with reference to FIG. 4, the relationship between various elements in the automatic traveling device will be described. The vehicle direction 16 indicates the straight running direction of the vehicle 19. The steering angle 15 is an angle formed between the vehicle direction 16 and the rotation surface of the wheel 14. The target direction 18 refers to an absolute direction in which the vehicle 19 should travel, and can be expressed in the same unit as the vehicle direction 16.

The terrestrial magnetism sensor 1 is composed of a terrestrial magnetism detecting unit 101 and a sensor driving unit 102, and is attached to at least the vehicle 19 in two orthogonal directions XY. The sensor driving unit 102 has a magnetic core and a current applying unit inside, generates a pulse current with the power supplied from the power supply 5, applies the pulse current to the magnetic core, and generates a self-magnetic field. The terrestrial magnetism detection unit 101 has a detection coil and an amplification circuit inside, detects an external magnetic field using a self-magnetic field generated by the sensor driving unit 102, and outputs the magnetic direction of an analog signal by the amplification circuit. This magnetic azimuth indicates that the vehicle azimuth 16 in FIG. 4 is output as a magnetic azimuth component orthogonal to two axes. The vehicle direction of the analog signal output from the geomagnetic sensor 1 is AD
The signal is converted into a digital signal by the AD conversion circuit 202 in the converter 2 and transmitted to the CPU 3.

The CPU 3 has an azimuth calculation unit 301, a steering control calculation unit 302, and an actuator drive amount calculation unit 303. The vehicle direction of the digital signal transmitted to the CPU 3 is input to the direction calculation unit 301. At this time, the azimuth of the vehicle detected by the geomagnetic sensor 1 is affected by the magnetization of the vehicle and includes a deviation from the true value.
In step 01, a correction operation is performed to improve the accuracy of the vehicle azimuth using a correction value stored in advance, and the obtained true vehicle azimuth is transmitted to the steering control operation unit 302. The steering control calculation unit 302 includes an A / D conversion circuit 201 from the mode switch 6 in advance.
The target direction (corresponding to the target direction 18 in FIG. 4) manually input through is stored as a reference value. As the calculation algorithm in the steering control calculation unit 302, for example, PI
There is a D control algorithm. In the PID control algorithm, a steering control command (corresponding to the steering control command 17 in FIG. 4 (a command to displace the vehicle in the direction of the white arrow 16)) for causing the vehicle to follow the target direction is calculated. The steering control command is input to the actuator drive amount calculation unit 303. The steering angle detected by the steering angle sensor 4 attached to the steering mechanism 12 is input to the actuator drive amount calculation unit 303 as a digital signal via the AD conversion circuit 204 as needed. The actuator drive amount calculation unit 303 calculates an actuator drive amount. The actuator drive amount corresponds to the amount of change from the current steering angle so that the steering angle follows the input steering control command, and thus corresponds to the opening amount of the steering control valve 9. The actuator drive amount is output to the DA conversion circuit 7.

[0006] The DA conversion circuit 7 converts the input digital signal into an analog signal again, and transmits the analog signal to the actuator control circuit 8. The actuator control circuit 8 converts the analogized actuator drive amount into a PWM signal so as to correspond to the interface of the steering control valve 9, and outputs the PWM signal to the steering control valve 9. A CPU capable of directly generating and outputting a PWM signal is also commercially available, and when the CPU is mounted, the DA conversion circuit 7 can be omitted. The hydraulic power source 11 supplies pressure oil to the steering control valve 9 and the hydraulic actuator 10, and operates by receiving power from an engine on the vehicle side. The operation of the hydraulic actuator 10 is determined by the open / close state of the steering control valve 9, and the actuator operation is transmitted to the steering mechanism 12 to automatically control the steering angle of the wheels 13.

[0007]

As described above, the azimuth sensor has an advantage that the power consumption required for driving is small, but on the other hand, unless the weak geomagnetism is stably converted into a voltage signal. Therefore, there is also a structural problem that resistance to supply voltage fluctuation due to overload of the power supply is small. When an experiment was conducted in which the sensor was fixed and the supply voltage was input at a value deviating from the standard width by several volts, it was confirmed that the sensor detection value changed and an error of several degrees occurred at the azimuth angle level. In practice, for example, when the tractor during cultivation land maintenance work encounters obstacles such as rocks during cultivation and temporarily gets overloaded when the engine of the vehicle is overloaded, the power supply becomes full and the direction sensor It is expected that the voltage of the power distributed to the power supply will fluctuate, and that the power supply will also fluctuate. in this case,
Although the vehicle direction does not change, the sensor detection value fluctuates and outputs a direction deviated from the correct direction. When an error occurs in the azimuth detected by the geomagnetic sensor, the steering control calculation unit calculates a steering control command for causing the vehicle to follow the erroneous azimuth, and thus the traveling route of the vehicle is distorted.
As described above, the conventional steering control device has a problem to be solved with respect to the resistance to the fluctuation of the power supply voltage. The present invention has been made in view of the above problems, and has a steering control device that reduces an error in a traveling direction due to a fluctuation in a power supply voltage and thus improves the stability of steering control of an automatic traveling vehicle outdoors. In the offer.

[0008]

The gist of the present invention to achieve the above object lies in the following inventions. [1] The actuator (10) is controlled according to an actuator drive signal given to the actuator control means (9), and the steering mechanism (1) is controlled by the actuator (10).
2) a direction sensor (1) mounted on a vehicle that automatically travels in a target direction by driving the direction sensor and detects the direction of the vehicle; and a means (6) for inputting the target direction.
A power supply (5) for supplying electric power for operating the azimuth sensor (1); a steering angle input means (4) for inputting a steering angle according to steering by the steering mechanism (12); The steering control device includes: a calculation unit (3) that calculates an actuator drive amount based on the steering angle and the steering angle; and an actuator drive unit (8) that generates the actuator drive signal based on the actuator drive amount. The means (3) sets the actuator drive amount to a value that sets the steering angle of the steering mechanism (12) to 0 ° when the voltage of the electric power deviates from a predetermined range. .

[2] The vehicle azimuth, target azimuth, steering angle and the voltage are converted into digital data by AD conversion means (2) and supplied to the arithmetic means (3), and the arithmetic means (3) The actuator control amount is converted into analog data by a DA conversion means (7) and supplied to the actuator drive means (8). The calculation means (3) includes an azimuth calculation unit (301) and a steering control. A control operation unit (302), a voltage fluctuation detection unit (304), a command reset unit (305), and an actuator drive amount operation unit (303) are provided. The received vehicle direction is converted into data of a predetermined format, and the steering control calculation unit (302)
Receives the vehicle azimuth and the target azimuth from the azimuth calculation unit (301) and the AD conversion means (2), generates a command for following the vehicle azimuth with the target azimuth, and generates the voltage fluctuation detection unit ( 304) determines whether the voltage received from the A / D conversion means (2) is in a normal power supply state within the predetermined range or is in a power supply abnormal state where the voltage deviates from the predetermined range. 3
05), the command is input, the command is output as it is when the power supply is normal, and the zero command for setting the steering angle to 0 ° is output when the power supply is abnormal, and the actuator drive amount is output. The steering control device according to [1], wherein the calculation unit (303) calculates the actuator drive amount from the steering angle and the zero command received from the AD conversion unit (2).

[3] The steering control device according to [1] or [2], wherein the azimuth sensor (1) is a geomagnetic sensor.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a diagram in which a main part configuration of the present invention is added to the conventional processing path shown in FIG. The configuration of the embodiment will be described with reference to FIG.
The sensor driving unit 102 outputs the amount of voltage supplied from the power supply 5 as information as an analog signal. The voltage of the analog signal is converted into a digital signal by an AD conversion circuit 203 (corresponding to the above-described AD conversion means), and is input to a voltage fluctuation detection unit 304 in the CPU 3.

A circuit for determining whether or not the voltage represented by the input signal is within a specified range is
And a circuit for outputting the result of the determination as a determination signal. The voltage fluctuation detection unit 304 sets the determination signal to GOOD if the input signal is within a predetermined range to indicate that the power supply is normal, and sets the determination signal to indicate that the power supply is abnormal if the input signal is outside the predetermined range. Is output to the command reset unit 305 as FAIL.

The command reset unit 305 determines that the judgment signal is G
During the OOD period, the steering control calculation unit 302
The steering control command calculated in step (1) is output to the actuator drive amount calculation unit 303 as it is. During the FAIL period, the steering control command is converted into a zero command for setting the steering angle to 0 ° (hereinafter, this conversion is referred to as zero clear). The driving amount is output to the driving amount calculation unit 303. Therefore, during the FAIL period, the actuator drive amount calculation unit 303 calculates the actuator drive amount for correcting the current steering angle to 0 ° regardless of the azimuth information including the error output from the geomagnetic sensor 1, and calculates the actuator drive amount. The amount is output to the actuator control circuit 8 (corresponding to the above-described actuator driving means) via the DA conversion circuit 7.

In this embodiment, the voltage of the sensor driving unit 102 is selected as the monitoring target of the sensor driving voltage. However, the present invention is not limited to this.
A configuration may be adopted in which the power supply output amount is input to the voltage fluctuation detection unit 304 via the power supply circuit 03. As the power output amount,
There are a voltage obtained by dividing the output voltage of the power supply 5, a current proportional to the output voltage, and the like. In short, the voltage fluctuation detection unit 304 only needs to be able to monitor the output amount that causes the output fluctuation of the geomagnetic sensor 1 and the output amount of the output of the geomagnetic sensor 1 that is linked to the change. In FIG. 1, for convenience of explanation of the input / output, the AD conversion circuit is represented for each input / output, and is collectively referred to as the AD converter 2. A configuration in which the AD conversion of the vehicle azimuth, the voltage, and the steering angle is covered by one AD conversion circuit may be adopted.

Next, the operation of the present embodiment will be described with reference to FIG. It is assumed that the steering control (for example, steering control) is started for a certain target azimuth input by operating the mode SW 6 (corresponding to the means for inputting the target azimuth described above). In the initial period X, there is no overload or the like in running, and the voltage fluctuation of the power supply 5 is within a specified range (period X in chart A). Since the detection value of the geomagnetic sensor 1 also matches the target direction, the vehicle is in a state of traveling toward the target direction (period X in chart B). Since the voltage of the power supply 5 is within the specified range, the determination signal calculated by the voltage fluctuation detection unit 304 is also output as GOOD (Chart C).
Period X). Therefore, the steering control command calculated by the steering control calculator 302 is input to the processing block of the actuator drive amount calculator 303 without being cleared to zero. At present, since the target direction and the vehicle direction match, the opening amount of the steering control valve 9 (corresponding to the above-described actuator control means) is controlled so that the steering angle of the vehicle is maintained without any change. (Period X in chart D). The traveling route of the vehicle is in a straight traveling state without shifting laterally (period X in chart E).

However, when the engine of the vehicle is overloaded due to, for example, the influence of the traveling route state, and the supply voltage from the power supply 5 to the geomagnetic sensor 1 shows a fluctuation exceeding a specified range (period Y in chart A). The azimuth error occurs in the detection value of the geomagnetic sensor 1 under the influence of the fluctuation (period Y in the chart B). At this time, in the conventional example, the steering control command is calculated based on the detection value including the azimuth error, so that the opening amount of the steering control valve 9 is controlled according to an erroneous command (broken line in the period Y of the chart D). . As a result, the vehicle temporarily travels in an azimuth different from the target azimuth, and the traveling route shifts in the lateral direction (broken line in period Y of chart E).

On the other hand, in the embodiment of the present invention, in the period Y, the voltage fluctuation
Output as IL (period Y in chart C). FAIL
The command reset unit 305 that has received the determination signal of (1) clears the steering control command including the error to zero, and the actuator control circuit 8 outputs an actuator drive signal for setting the steering angle of the wheel 13 to 0 °. Therefore, the opening amount of the steering control valve 9 is controlled to the opening amount that maintains the straight running state, which is the current state of progress (solid line in the period Y in the chart D), and the traveling route also maintains the direction in the period X (the period in the chart E). Y solid line).

When the power supply voltage returns within the specified range (period Z in chart A), there is no error in the detected value of the geomagnetic sensor (period Z in chart B). Since the voltage of the power supply has returned to the specified range, the determination signal calculated by the voltage fluctuation detection unit 304 also returns to GOOD (period Z in chart C), and the actuator drive amount calculation unit 30 similarly to period X.
In blocks 3 and below, the processing based on the steering control command based on the value detected by the geomagnetic sensor 1 is restarted.

[0019]

As described above in detail with reference to the embodiments, the steering control device according to the present invention controls the steering in such a manner that the vehicle is maintained in the running state immediately before the power fluctuation occurs. Since the system is adopted, it is possible to provide a steering control device capable of stably controlling the steering of an automatic traveling vehicle outdoors.

[Brief description of the drawings]

FIG. 1 is a block circuit diagram showing one embodiment of the present invention.

FIG. 2 is a time chart of control block processing and operation in FIG. 1 in the embodiment.

FIG. 3 is a block circuit diagram showing a conventional example.

FIG. 4 is a diagram showing correspondence between words for explaining steering control and a meaningful state;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Geomagnetic sensor 2 ... AD converter 3 ... CPU 4 ... Steering angle sensor 5 ... Power supply 6 ... Mode SW 7 ... DA conversion circuit 8 ... Actuator control circuit 9 ... Steering control valve 10 ... Hydraulic actuator 11 ... Hydraulic power source 12 ... Steering mechanisms 13, 14 Wheels 15 Steering angle 16 Vehicle direction 17 Steering control command 18 Target direction 19 Vehicle 101 Geomagnetism detecting unit 102 Sensor driving unit 201, 202, 203, 204 AD conversion circuit 301 ... Azimuth calculation unit 302 ... Steering control calculation unit 303 ... Actuator drive amount calculation unit 304 ... Voltage fluctuation detection unit 305 ... Command reset unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Osamu Yukimoto, Inventor: 1-40-2, Nisshin-cho, Omiya-shi, Saitama Prefecture Within the Research Institute for Biological Sciences (72) Inventor: Satoshi Yamamoto, 1-chome, Nisshin-cho, Omiya-shi, Saitama 40-2, Biological System-Specific Industrial Technology Research Promotion Organization (72) Inventor Yosuke Matsuo 1-chome, Nisshin-cho, Omiya-shi, Saitama F-term (reference) 2B043 AA04 AB06 BA02 BA08 BA09 BB01 BB03 BB06 DA13 DA17 DB17 EA02 EB05 EC13 EC14 EC16 EC19 ED01 ED02 ED03 3D032 CC20 CC26 DA03 DD09 EB04 EC34 GG07 5H301 BB01 BB02 CC03 GG16 HH02 LL06 LL11 LL16 MM04 MM07 MM09 MM09

Claims (3)

[Claims] An actuator is controlled in accordance with an actuator drive signal provided to an actuator control means,
The vehicle is mounted on a vehicle that automatically travels in a target direction by driving a steering mechanism by the actuator. The direction sensor detects the direction of the vehicle, means for inputting the target direction, and operates the direction sensor. A power supply for supplying electric power, steering angle input means for inputting a steering angle corresponding to steering by the steering mechanism, arithmetic means for calculating an actuator drive amount based on the vehicle direction, the target direction, and the steering angle; An actuator drive unit that generates the actuator drive signal based on an actuator drive amount, wherein the calculation unit sets the steering angle of the steering mechanism to 0 ° when the voltage of the power supply deviates from a predetermined range. A steering control device characterized in that the actuator drive amount is set to a value that: 2. The vehicle azimuth, target azimuth, steering angle and the voltage are converted into digital data by AD conversion means and supplied to the arithmetic means, and the arithmetic means is a digital computer. The data is converted into analog data by a DA converter and supplied to the actuator driver. The calculator includes an azimuth calculator, a steering control calculator, a voltage fluctuation detector, a command reset unit, and an actuator drive calculator. An azimuth calculation unit configured to convert the vehicle azimuth received from the A / D conversion unit into data in a predetermined format, wherein the steering control calculation unit includes the azimuth calculation unit and the AD
Receiving the vehicle azimuth and the target azimuth from the conversion means, and generating a command for following the vehicle azimuth to the target azimuth, wherein the voltage fluctuation detection unit detects that the voltage received from the AD conversion means is within the predetermined range. The command reset unit receives the command, and outputs the command as it is when the power supply is in a normal state, or determines whether the voltage is in a normal voltage state or a voltage abnormal state in which the voltage deviates from the predetermined range.
When the power supply is in an abnormal state, a zero command for setting the steering angle to 0 ° is output, and the actuator drive amount calculation unit is configured to output the actuator command from the steering angle received from the AD conversion unit and the output of the command reset unit. The steering control device according to claim 1, wherein the driving amount is calculated. 3. The steering control device according to claim 1, wherein the direction sensor is a geomagnetic sensor.