JP7192822B2 - Steering angle estimation device, steering device, and steering angle estimation method - Google Patents

Description

TECHNICAL FIELD The present disclosure relates to a steering angle estimating device, a steering device, and a steering angle estimating method, and more particularly to technology suitable for automatic steering.

2. Description of the Related Art Conventionally, various automatic steering systems have been proposed as steering systems mounted on vehicles, which control the operation of an actuator based on the sensor value of a steering angle sensor (see, for example, Patent Document 1). Various steering angle sensors for detecting the steering angle of a steering system have also been proposed (for example, see Patent Documents 2 and 3).

Japanese Patent Application Laid-Open No. 2004-352120 JP 2013-44557 A JP 2007-132685 A

The steering angle sensor as described above is generally attached to the steering shaft, column unit, or the like with a mechanical assembly error (so-called backlash). Therefore, there may be a deviation due to a mechanical error between the sensor value of the steering angle sensor and the actual steering angle. As a result, when automatic steering control is performed based on the sensor value of the steering angle sensor, there is a problem that controllability is deteriorated and stable automatic steering control cannot be performed.

The technology of the present disclosure has been made in view of the above circumstances, and aims to estimate and acquire the actual steering angle of the steering system with high accuracy.

The estimation device of the present disclosure includes a steering angle sensor that detects a steering angle of a steering device, a motor rotation angle sensor that detects an electrical angle of a motor capable of applying a steering force to the steering device, and an actual steering angle of the steering device. and an actual steering angle estimating unit that estimates an angle conversion value obtained by converting the electrical angle detected by the motor rotation angle sensor into a steering absolute angle, and the steering angle sensor When a difference from the detected steering angle is smaller than a predetermined value, the angle conversion value is estimated as the actual steering angle.

Moreover, it is preferable that the predetermined value is set based on a mechanical error of the steering angle sensor.

The steering system of the present disclosure is characterized by comprising an automatic steering control section that controls the operation of the motor based on the actual steering angle estimated by the actual steering angle estimation section and a predetermined target steering angle. .

The estimation method of the present disclosure detects the steering angle of a steering device, detects the electrical angle of a motor capable of applying a steering force to the steering device, and converts the detected electrical angle into a steering absolute angle. and estimating the converted angle value as the actual steering angle of the steering device when a difference from the detected steering angle is smaller than a predetermined value.

According to the technology of the present disclosure, it is possible to estimate and acquire the actual steering angle of the steering device with high accuracy.

1 is a schematic overall configuration diagram showing a steering device according to an embodiment; FIG. 1 is a schematic functional block diagram showing a control device according to an embodiment and related peripheral configurations; FIG. It is a schematic diagram explaining the comparison of the sensor value of the steering angle sensor which concerns on this embodiment, and a motor rotation angle sensor.

A steering angle estimating device, a steering device, and a steering angle estimating method according to the present embodiment will be described below with reference to the accompanying drawings. The same parts are given the same reference numerals, and their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

[overall structure]
FIG. 1 is a schematic overall configuration diagram showing a steering device 1 according to this embodiment.

The steering system 1 is, for example, an automatic steering system for a vehicle, and mainly includes an operation unit 10, a steering unit 20, a steering motor 30 as an actuator, a front camera 40, and a control device 100. .

The operation unit 10 has a steering wheel 11 as an operation member operated by the driver, a column unit 11A arranged substantially at the center of the steering wheel 11, and a steering shaft 12. As shown in FIG. The column unit 11A is provided with an operating lever such as a direction indicator. One end of the steering shaft 12 is fixed to the column unit 11A so as to be integrally rotatable.

The steering shaft 12 is provided with a steering angle sensor 13 that detects the steering angle of the steering wheel 11 (the rotation angle of the steering shaft 12). The steering angle sensor 13 has a coil unit (not shown) fitted to the main body with a pin or the like, and is attached to the column unit 11A by fitting the coil unit with a pin or the like. A steering angle sensor value _{θ_S} detected by the steering angle sensor 13 is transmitted to the electrically connected control device 100 .

The steering unit 20 is, for example, a rack and pinion type steering device, and includes a pinion shaft 21 connected to the steering shaft 12 via a universal joint 14 and a rack 22A that meshes with the pinion 21A of the pinion shaft 21. and a rack shaft 22 with a That is, when a rotational force is transmitted from the steering shaft 12 to the pinion shaft 21, the rotational motion is converted into linear motion, and the rack shaft 22 moves in the axial direction. The rack shaft 22 extends in the vehicle width direction, and left and right steering wheels 24L, 24R are rotatably provided at both ends of the rack shaft 22 via tie rods 23L, 23R.

The steering motor 30 is, for example, a three-phase brushless motor that rotates based on three-phase (U, V, W) drive power, and applies a rotational force (steering torque) to the pinion shaft 21 (or the steering shaft 12). It is designed to give Note that the steering motor 30 may be provided so as to transmit steering torque to the rack shaft 22 .

The steering motor 30 is provided with, for example, a motor rotation angle sensor 31 configured by a magnetic pole position detection encoder such as a resolver. A motor rotation angle sensor 31 detects a motor rotation angle (hereinafter referred to as an electrical angle value _{θ_E} ) based on an electrical signal or the like generated by reactance change between the rotor and stator of the steering motor 30 . The electrical angle value _{θ_E} detected by the motor rotation angle sensor 31 is transmitted to the electrically connected control device 100 .

The front camera 40 captures images of the front of the vehicle and the road surface on which the vehicle is traveling, and generates image data of these images. Image data generated by front camera 40 is transmitted to electrically connected control device 100 .

[Control device]
FIG. 2 is a schematic functional block diagram showing the control device 100 according to this embodiment and related peripheral configurations.

The control device 100 is, for example, a device such as a computer that performs computation, and includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), an input port, and an output port, which are connected to each other via a bus or the like. etc., and run the program.

Further, the control device 100 functions as a device including an automatic steering control section 110 and a control steering angle setting section 120 (an actual steering angle estimation section of the present disclosure) by executing a program. In this embodiment, each of these functional elements is described as being included in the control device 100, which is integrated hardware, but any part of these can also be provided in separate hardware.

The automatic steering control unit 110 calculates a target steering angle θ _{_Tag} necessary for the vehicle to travel without deviating from the lane based on image data and the like transmitted from the front camera 40, and calculates the calculated target steering angle θ _Tag. Automatic steering control is performed to control the operation of the steering motor 30 according to the angle _{θ_Tag} . As a specific example, the automatic steering control unit 110 _{sets a} deviation Δθ (=θ _{_Tag} −θ _{_Corr} ), automatic steering control is performed by feedback-controlling the operation of the steering motor 30 .

Based on the steering angle sensor value _{θ_S} transmitted from the steering angle sensor 13 and the electrical angle value _{θ_E} transmitted from the motor rotation angle sensor 31, the steering angle setting unit 120 for control performs the aforementioned automatic steering control. A control steering angle value _{θ_Corr} to be used is set.

Here, since the motor rotation angle sensor 31 shown in FIG. 1 is connected to the steering shaft 12 with substantially no mechanical assembly error (play), The value _{θ_E} is very precise. However, the electrical angle value _{θ_E} is divided into electrical angles corresponding to the number of magnetic poles of the steering motor 30, and the steering shaft 12 rotates multiple times (one or more revolutions) _. The rotation angle of the steering shaft 12 (hereinafter referred to as the actual steering angle _{θ_Act} ) cannot be used as it is for automatic steering control.

On the other hand, the steering angle sensor 13 shown in FIG. A predetermined deviation (for example, ±4 to 5 degrees) may occur between _{_S and the actual steering angle θ _Act .} Therefore, if the steering angle sensor value θ _{_S} is used as it is for automatic steering control, it becomes a factor that causes a decrease in controllability.

Therefore, in the present embodiment, the highly accurate electrical angle value θ _{_E} is used for the learning correction of the actual steering angle θ _{_Act} , thereby improving the setting accuracy of the control steering angle value θ _{_Corr} . It enables realization of steering control. It should be noted that the correction value obtained by aligning the actual steering angle _{θ_Act} and the electrical angle value _{θ_E} (absolute angle alignment) is obtained in advance when the vehicle is manufactured before shipment from the factory and stored in the memory of the control device 100. shall be

FIG. 3 shows, for example, in a configuration in which the number of magnetic poles Mn of the steering motor 30 is "4" and the electrical angular resolution Er is "1023", the actual steering angle _{θ_Act} is 45 degrees, and accordingly the electrical angle value _{θ_E} is "512", (A) is when there is no deviation in the steering angle sensor value _{θ_S} , and (B) is when there is +5 degree deviation in the steering angle sensor value _{θ_S} due to assembly error, ( C) shows a case where the steering angle sensor value θ _{_S} has a deviation of -5 degrees due to an assembly error.

As shown in FIG. 3A, when there is no deviation in the steering angle sensor value _{θ_S} , the steering angle conversion value _{θ_Cal obtained} by converting the electrical angle value _{θ_E} of “512” into the steering angle (absolute angle) is about 45. and becomes substantially equal to the value 45 of the steering angle sensor value _{θ_S} . Here, the steering angle conversion value _{θ_Cal} is obtained by the following formula (1).

_{θ_Cal} =(360× _{θ_E} )/(Er×Mn) (1)
However, θ _{_E} = electrical angle value
Er = electrical angular resolution
_Mn =number of magnetic _poles On the other hand, as shown in FIG. The steering angle sensor value θ _{_S} becomes -5=40. Further, as shown in FIG. 3(C), when the steering angle sensor value _{θ _S} has a deviation of -5 degrees due to a mechanical error, the steering angle sensor value The value _{θ_S} is +5=50.

That is, the steering angle sensor value θ _{_S} is the divergence caused by the mechanical error of the steering angle sensor 13 with respect to the steering angle conversion value θ _{_Cal} obtained by converting the electrical angle value θ _{_E} without mechanical error into an absolute angle. If it is within the range (for example, ±4 to 5 degrees), the steering angle conversion value θ _{_Cal} can be regarded as the actual steering angle θ _{_Act} . In other words, if the difference between the steering angle conversion value _{θ_Cal converted from the electrical angle value θ_E and} the steering angle sensor value _{θ_S} is smaller than the mechanical error of the steering angle sensor 13, the steering angle conversion value θ _{_Cal} can be set as the control steering angle value _{θ_Corr} used for automatic steering control.

The control steering angle setting unit 120 first determines whether or not the steering angle conversion value _{θ_Cal} satisfies the conditions shown in the following formulas (2) and (3) when the vehicle starts running such as when the engine is started. In equations (2) and (3), A is a divergence angle value (for example, ±5 degrees) caused by a mechanical error of the steering angle sensor 13 . This divergence angle value A is obtained in advance through experiments or the like and stored in the memory of the control device 100 .

_{θ_Cal} +(360/Mn)×n> _{θ_S} -A (2)
_{θ_Cal} +(360/Mn)×n< _{θ_S} +A (3)
In formulas (2) and (3), n is represented by the following formula (4). In Expression (4), Ns is the steering rotation speed (rounded up to the nearest whole number).

n=((Mn×Ns)−1)×(−1) to ((Mn×Ns)−1) (4)
When the conditions of the above formulas (2) and (3) are satisfied, the control steering angle setting unit 120 sets the control steering angle value θ _{_Corr} obtained from the following formula (5) as the steering angle for automatic steering control. set as

_{θ_Corr} = _{θ_Cal} +360/(Mn×n) (5)
Thereafter, after the control steering angle setting unit 120 sets the control steering angle value θ _{_Corr} obtained from the formula (5), the electric current transmitted from the motor rotation angle sensor 31 in real time is calculated based on the set value. A steering angle for automatic steering control is sequentially set to a value counted from the angle value _{θ_E} , and transmitted to the automatic steering control section 110 in real time.

In short, according to the present embodiment, the electrical angle value _{θ_E} of the motor rotation angle sensor 31, which is highly accurate but cannot handle multiple rotations of the steering shaft 12, and is affected by assembly errors, A control steering angle value θ _{_Corr} used for automatic steering control can be set with high accuracy based on the correlation with the steering angle sensor value θ _{_S} of the steering angle sensor 13 capable of detecting an absolute angle corresponding to rotation. It is As a result, the controllability of automatic steering control is improved, and stable automatic steering control can be realized.

[others]
It should be noted that the present disclosure is not limited to the embodiments described above, and can be appropriately modified and implemented without departing from the gist of the present disclosure.

For example, in the above embodiment, if the difference between the steering angle conversion value _{θ_Cal converted from the electrical angle value θ_E and} the steering angle sensor value _{θ_S} is larger than the mechanical error of the steering angle sensor 13, In addition to prohibiting automatic steering control, a diagnosis function may be added to notify the driver of an abnormality in the steering device 1 .

Moreover, although the steering system 1 has been described as an automatic steering system, it can also be widely applied to an electrically assisted steering system or the like in which the steering motor 30 assists the driver's steering operation.

1 steering device 10 operation unit 11 steering wheel 11A column unit 12 steering shaft 13 steering angle sensor 20 steering unit 30 steering motor 31 motor rotation angle sensor 100 control device 110 automatic steering control unit 120 control steering angle setting unit (actual steering angle estimation part)

Claims (4)

a steering angle sensor that detects the steering angle of the steering device;
a motor rotation angle sensor that detects an electrical angle of a motor connected to a steering shaft and capable of applying a steering force to the steering device;
and an actual steering angle estimating unit that estimates the actual steering angle of the steering device,
The actual steering angle estimating unit divides the electrical angle detected by the motor rotation angle sensor by the number of magnetic poles of the motor and the electrical angular resolution of the motor, thereby converting it into an absolute steering angle. 2. A steering angle estimating device, wherein when a difference from the steering angle detected by the steering angle sensor is smaller than a predetermined value, the angle conversion value is estimated as the actual steering angle. The steering angle estimation device according to claim 1, wherein the predetermined value is set based on a mechanical error of the steering angle sensor. A steering device comprising the steering angle estimating device according to claim 1 or 2,
A steering system comprising an automatic steering control section that controls operation of the motor based on the actual steering angle estimated by the actual steering angle estimation section and a predetermined target steering angle. The steering angle of the steering device is detected, and the electrical angle of a motor capable of applying a steering force to the steering device is detected by a motor rotation angle sensor connected to the steering shaft. and the electrical angular resolution of the motor, and when the difference between the detected steering angle and the angle conversion value converted into the steering absolute angle is smaller than a predetermined value, the angle conversion value is A steering angle estimation method characterized by estimating as an actual steering angle.

Images