JP4211366B2 - Steering state detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a steering wheel steering state detection device.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, an electric power steering device that assists rotation of an output shaft by steering of a steering wheel with a motor is known. In such a power steering device, the steering angle of the steering wheel and the torque applied to the output shaft are detected, and the rotation of the output shaft is assisted based on the detected value.
[0003]
As the steering wheel state detection device for detecting the steering state of the steering wheel by the driver, the following (1) to (4) have been proposed.
[0004]
{Circle around (1)} One steering wheel state detection device determines whether the steering wheel is released when the absolute value of the steering torque estimated by the state determination unit is less than a threshold value and a predetermined time has elapsed (see Patent Document 1 below). reference).
[0005]
(2) In addition, the manual operation force applied to the steering wheel by the driver is estimated, and the steering feeling is improved by giving the steering wheel a resistance force that acts in the direction of preventing rotation only when the manual operation force is less than the set value. Is also known (see Patent Document 2 below).
[0006]
(3) Further, there is also known one equipped with a transmission ratio variable mechanism that changes the transmission ratio between the steering angle of the steering wheel and the turning angle of the wheel by the driving force of the actuator (see Patent Document 3 below). ).
[0007]
(4) In addition, the steering speed is detected from the output of the steering angle sensor, and when the steering speed is maintained from zero to a predetermined value in the gentle steering state, no slight vibration is transmitted to the steering wheel and the steering speed increases. A device capable of obtaining quick power assist motor response is known (see Patent Document 4 below).
[0008]
Related documents are as follows.
[0009]
[Patent Document 1]
JP 2002-104223 A [Patent Document 2]
JP-A-4-176811 [Patent Document 3]
Japanese Patent Laid-Open No. 11-321684 [Patent Document 4]
JP 2000-142433 A
[Problems to be solved by the invention]
However, in order to assist the rotation of the output shaft, the steering state of the steering wheel by the driver is important. However, the above-described control does not reflect the driver's direct steering intention, and the rotation assistance is accurate. May not be done.
[0011]
For example, when an external force from the road surface is transmitted to the handle via the wheel and the output shaft while the steering wheel is held, torque is generated and it is determined that the torque is during steering by the driver. The above assistance is performed regardless of the driver's intention.
[0012]
The present invention has been made in view of such problems, and an object of the present invention is to provide a steering wheel state detection device capable of detecting a more accurate steering wheel state.
[0013]
[Means for Solving the Problems]
In order to solve the above-described problem, a steering wheel state detection device according to the present invention includes an input shaft coupled to a handle, an output shaft coupled to the input shaft, and a steering angle sensor that detects a steering angle of the handle. A steering wheel steering state detection device including a torque sensor for detecting torque between the input shaft and the output shaft, and a time differential value of the steering angle output from the steering angle sensor and output from the torque sensor. Detection means for detecting a steering state of the steering wheel according to the product of the torque is provided , and the detection means is configured such that the product is equal to or less than a predetermined work amount threshold and the torque is equal to or less than a predetermined torque threshold. In some cases, it is determined that the handle is in a released state .
[0014]
According to this steering wheel steering state detecting device, the detecting means detects the steering wheel steering state according to the “product” of the time differential value of the steering angle and the torque. That is, the driver's direct steering operation is a work amount for the steering wheel. If this work amount is detected, a more accurate steering state of the steering wheel can be detected. In other words, the work amount is a “product” of the time differential value of the steering angle and the torque, and therefore, in this device, an accurate steering state of the steering wheel can be detected.
[0015]
As a preferable example of determining the steering state, the detection means determines that the steering is being performed when the “product” exceeds a predetermined work amount threshold value. That is, when the work amount exceeds the work amount threshold value, it can be determined that the steering wheel is steered. That is, in this case, the detection means determines that the steering wheel is actually steered (the steering wheel is actually moved).
[0016]
As another example of determining a suitable steering state, when the detection unit has the “product” equal to or less than a predetermined work amount threshold and the torque is equal to or less than a predetermined torque threshold, It is characterized in that it is determined that the hand is released.
[0017]
In other words, the steering wheel is not steered because the workload is below a predetermined workload threshold value. In such a case, either (2) the handle is released or (3) the steering is maintained. It is a state.
[0018]
{Circle around (3)} If the steering is maintained, the output shaft will be twisted with respect to the input shaft due to external force from the road surface, and torque will be detected. Therefore, if the detected torque is equal to or less than the torque threshold value, the detection means can determine that it is in the (2) release state.
[0019]
As an example of determination of the remaining preferable steering state, when the detection unit has the “product” equal to or smaller than a predetermined work amount threshold and the steering angle is equal to or smaller than a predetermined steering angle threshold, It is characterized in that it is determined that the steering is maintained.
[0020]
That is, as described above, the work is not steered because the work is equal to or less than the predetermined work threshold. In such a case, the steering wheel is in the (2) hand release state or the (3) steering control. One of the states.
[0021]
(2) If it is in the let-off state, no torque is generated, but the steering angle will be off by external force from the road surface. Therefore, if the detected steering angle is equal to or smaller than the steering angle threshold, the detection means can determine that the vehicle is in the (3) steering state.
[0022]
Further, the steering wheel steering state detection device of the present invention further includes a motor for assisting the rotation of the output shaft according to the detection result of the steering state by the detecting means. When the steering state of the steering wheel is detected, only in the actual steering state, in principle, rotation assistance of the output shaft can be performed, and therefore rotation assistance contrary to the driver's intention can be suppressed.
[0023]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a configuration diagram showing an outline of a configuration of a steering device 20 mounted on a vehicle.
[0024]
The steering device 20 includes a handle 22, a steering shaft (input shaft) 24 that transmits the steering torque of the handle 22 to the rack 28 via a pinion gear (output shaft) 26, and changes the turning angle of the steered wheels 30, 32; A motor 34 that outputs output torque to the rack 28 via a speed reducer 36 and a pinion gear 38, and an electronic control unit (ECU: detection means) 50 that controls the entire apparatus are provided.
[0025]
The ECU 50 is configured as a microprocessor centered on the CPU 52, and includes a ROM 54 that stores a processing program, a RAM 56 that temporarily stores data, and an input / output port (not shown).
[0026]
The ECU 50 receives an axial torque Tp from a torque sensor 42 attached to the steering shaft 24, a steering angle θh from a steering angle sensor 40 attached to the steering shaft 24, a vehicle speed V from a vehicle speed sensor 58, and the like via an input port. Have been entered. Further, a drive signal to the motor 34 is output from the electronic control unit 50 through an output port.
[0027]
That is, the steering wheel state detection device includes a steering shaft 24 connected to the steering wheel 22, a pinion gear 26 connected to the steering shaft 24, a steering angle sensor 40 that detects the steering angle of the steering wheel 22, the steering shaft 24, And a torque sensor 42 for detecting torque between the pinion gears 26.
[0028]
The value of the steering angle θh output from the steering angle sensor 40 is time-differentiated by the ECU 50. Further, the value of the torque Tp output from the torque sensor 42 is multiplied by the time differential value Δθh / Δt of the steering angle θh by the ECU 50 (t is time). That is, the ECU 50 detects the steering state of the steering wheel according to the product W (= Δθh / Δt × Tp) of the time differential value Δθh / Δt and the torque Tp.
[0029]
The steering operation of the steering wheel 22 directly by the driver is a work amount with respect to the steering wheel 22, and by detecting this work amount, a more accurate steering state of the steering wheel can be detected. Since the work amount W is a “product” of the time differential value Δθh / Δt of the steering angle and the torque Tp, the ECU 50 calculates the work amount W, so that the driver can directly handle the steering operation, that is, accurately. It is possible to detect an appropriate steering state of the steering wheel.
[0030]
This steering wheel steering state detection device further includes a motor 34 that assists the rotation of the pinion gear 26 in accordance with the detection result of the steering state by the ECU 50. When the steering state of the steering wheel 22 is detected, the rotation assistance of the pinion gear 26 can be performed only in the actual steering state (the state in which the steering wheel is actually moved), and therefore, the rotation assistance against the intention of the driver. Can be suppressed.
[0031]
There are three types of steering wheel states by the driver: (1) actual steering state, (2) hand release state, and (3) steering state.
[0032]
The ECU 50 calculates a work amount W (= Δθh / Δt × Tp) according to the steering angle θh and torque Tp input thereto, and then determines the steering state of the steering wheel from the work amount W. The determination result and the torque The motor 34 is controlled according to Tp. This control method is as follows.
[0033]
When the determination result is (1) the actual steering state, the motor 34 may be rotated according to the torque Tp and the steering angle θh. The motor 34 can be rotated according to the work amount W, or the rotation control amount of the motor 34 can be changed according to the vehicle speed and the yaw rate, as is conventionally known. In the actual steering state, the motor 34 is driven.
[0034]
If the determination result is that the steering wheel is released (2), in principle, the motor 34 is not rotated according to the torque Tp and the steering angle θh. That is, because the handle 22 is rotated by an external force from the road surface, for example, if assistance is provided by the motor 34 in proportion to the steering angle θh, assistance is performed regardless of the driver's intention.
[0035]
Here, “in principle” refers to logic that assists the driver in operating mistakes, for example, in the case where the vehicle may roll over due to being released in an emergency, etc. It is possible to perform control such as rotating the motor 34.
[0036]
When the determination result indicates that the steering wheel is in the (3) steering state, in principle, the motor 34 is not rotated according to the torque Tp and the steering angle θh. That is, since the handle 22 is rotated by an external force from the road surface, for example, if assistance is provided by the motor 34 in proportion to the torque Tp, assistance is performed regardless of the driver's intention.
[0037]
Here, “in principle” means that a large force is applied to the steering of the steering wheel when a force is applied to the steering wheel in a direction opposite to the turning direction during vehicle turning, or when a so-called reverse steering wheel is applied. In this case, since it is the driver's intention to assist, the assist can be performed even in the steered state.
[0038]
Now, the steering state determination of the steering wheel by the ECU 10 is performed as follows.
[0039]
FIG. 2 is a graph showing the relationship between torque Tp, steering angle θh, steering angle time differential value Δθh / Δt, and work amount W with respect to time t.
[0040]
In the ECU 50, when the above-mentioned “product” = the work amount W exceeds the predetermined work amount threshold value W1 in the positive direction or exceeds the predetermined work amount threshold value −W1 in the negative direction, the steering wheel is steered. Judgment is time. The sign of the work amount W defined here is a value indicating the direction derived in the calculation, and it can be expressed that it is determined whether the absolute value of the work amount exceeds the work amount threshold value W1 in the calculation. it can. Thus, when the work amount W obtained in the ECU 50 exceeds the work amount threshold value W1, it can be determined that the driver is steering the steering wheel 22. That is, it is determined that this period is (1) the actual steering state (steering period).
[0041]
The ECU 50 determines that when the above-mentioned “product” = the work amount W (absolute value) is equal to or less than the predetermined work amount threshold value W1 and the torque Tp (absolute value) is equal to or less than the predetermined torque threshold value Tp1. {Circle around (2)} It is determined that the hand is released (hand-off period).
[0042]
In other words, since the work amount W (absolute value) is equal to or less than the predetermined work amount threshold value W1, the driver does not steer the handle 22. Or {circle around (3)} is either one of the steered state.
[0043]
{Circle around (3)} If the steering state is maintained, the pinion gear 26 will be twisted with respect to the steering shaft 24 by the external force from the road surface, and the torque Tp will be detected. Therefore, if the detected torque Tp is equal to or less than the torque threshold value Tp1, the ECU 50 can determine that it is in the state of (2) letting go.
[0044]
Further, the ECU 50 maintains the steering wheel (3) when the above-mentioned “product” is not more than the predetermined work amount threshold W1 and the steering angle θh (absolute value) is not more than the predetermined steering angle threshold θh1. It determines with it being a rudder state.
[0045]
That is, similarly to the above, since the work amount W is equal to or less than the predetermined work amount threshold value W1, the steering wheel 22 is not steered. ▼ It is one of the steering holding states.
[0046]
(2) If it is in the let-off state, no torque is generated, but the steering angle θh will be off by an external force from the road surface. Therefore, if the detected steering angle θh is equal to or smaller than the steering angle threshold θh1, the ECU 50 can determine that the vehicle is in the (3) steering state.
[0047]
Further, the above determination is determined when a state satisfying each condition determination condition continues for a predetermined period. In addition, the above-described threshold values and the predetermined period are determined in advance by selecting a suitable one from sample data when the vehicle is operated on an actual vehicle.
[0048]
In addition, during the actual steering period, a unique steering state can be determined.
[0049]
That is, at the times P1 and P2 in the figure, the following condition 1 is satisfied, and the work amount W indicates a value where the steering angle is the maximum value.
(Condition 1)
Work W = 0
Torque Tp (steering angle θh) ≠ 0
Differential value Δθh / Δt = 0
[0050]
At time P3, the following condition 2 is satisfied, indicating that the handle 22 is a displacement point that is switched from the forward direction to the reverse direction.
(Condition 2)
Workload W = 0,
Torque Tp = 0,
Steering angle θh = 0,
Differential value Δθh / Δt ≠ 0
[0051]
At times P4 and P5, it can be determined that the following condition 3 is satisfied and the handle 22 is located near the midpoint.
(Condition 3)
Workload W = 0,
Torque Tp = 0,
Steering angle θh = 0,
Differential value Δθh / Δt ≒ 0
[0052]
As described above, according to the determination control described above, various steering states of the steering wheel can be determined, which can be applied to various types of control.
[0053]
As described above, according to the steering wheel steering state detection device described above, the ECU 50 detects the amount of direct work given to the steering wheel 22 by the driver, so that a more accurate steering wheel steering state can be detected.
[0054]
【The invention's effect】
According to the steering wheel state detection device of the present invention, since the driver's direct work amount is detected, a more accurate steering wheel state can be detected.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an outline of a configuration of a steering device 20 mounted on a vehicle.
FIG. 2 is a graph showing the relationship among torque Tp, steering angle θh, steering angle time differential value Δθh / Δt, and work amount W with respect to time t.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 20 ... Steering device, 22 ... Steering wheel, 24 ... Steering shaft, 24 ... Input shaft, 26 ... Output shaft, 28 ... Rack, 30, 32 ... Steering wheel, 34 ... Motor, 36 ... Reduction gear, 38 ... Pinion gear, 40 ... Steering angle sensor, 42 ... torque sensor, 42 ... steering angle sensor, 50 ... electronic control unit, 58 ... vehicle speed sensor.

Claims (4)

An input shaft coupled to the handle;
An output shaft connected to the input shaft;
A steering angle sensor for detecting a steering angle of the steering wheel;
In a steering wheel state detection device comprising a torque sensor for detecting torque between the input shaft and the output shaft,
According to the product of the time differential value of the steering angle output from the steering angle sensor and the torque output from the torque sensor, the detection means detects a steering state of the handle , the detection means,
A steering wheel steering state detecting device , wherein when the product is equal to or smaller than a predetermined work amount threshold and the torque is equal to or smaller than a predetermined torque threshold, it is determined that the steering wheel is released . The detection means includes
The steering wheel steering state detection device according to claim 1, wherein when the product exceeds a predetermined work amount threshold value, it is determined that the steering wheel is actually moving and the steering wheel is being steered. The detection means includes
2. The steering wheel according to claim 1, wherein when the product is equal to or smaller than a predetermined work amount threshold value and the steering angle is equal to or smaller than a predetermined steering angle threshold value, it is determined that the steering wheel is in a steered state. The steering wheel steering state detection device as described.   The steering wheel steering state detection device according to claim 1, further comprising a motor that assists in rotation of the output shaft in accordance with a detection result of the steering state by the detection unit.

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