Vehicle lamp controller, vehicle lamp system, and vehicle lamp control method

Abstract

A vehicle lamp controller, a vehicle lamp system, and a vehicle lamp control method are provided. The vehicle lamp system includes an acceleration sensor, a vehicle lamp, and the vehicle controller. The controller includes a receiver configured to receive an acceleration information detected by the acceleration sensor, a control unit configured to derive a vehicle longitudinal direction acceleration and a vehicle vertical direction acceleration from the acceleration information, and to generate a control signal for instructing an adjustment of an optical axis of the vehicle lamp, based on a variation in a ratio between a temporal change amount of the vehicle longitudinal direction acceleration and a temporal change amount of the vehicle vertical direction acceleration during at least one of an acceleration and a deceleration of a vehicle, and a transmitter configured to transmit the control signal to an optical axis adjusting portion of the vehicle lamp.

Description

CROSS-REFERENCE TO RELATED APPLICATION

22( ) and,controlacontrolcontrolcontrol controller/control unit 228R2 stores a first acceleration range P1(+) and a second acceleration range P2(+) of the acceleration of the vehicle 300 as well as a first deceleration range P1(−) and a second deceleration range P2(−) of the deceleration (negative acceleration) of the vehicle 300 as information on a an acceleration range in which plotting is carried out to calculate a linear approximation (this information is hereinafter referred to as plot range information). This plot range information has a set of an acceleration side range and a deceleration side range. In this exemplary embodiment, the plot range information has two sets, one set including the first acceleration range P1(+) and first deceleration range P1(−), and the other set including the second acceleration range P2(+) and second deceleration range P2(−). The acceleration range and deceleration range can be set based on the amount of time variations in the vehicle speeds to be detected by the vehicle speed sensor 312 or the magnitude of the vehicle longitudinal direction components that can be obtained from the values detected by the acceleration sensor 316. The plot range information is stored in, for example, the memory 228R4.

For example, during the time from the start of the vehicle 300 to the stop thereof, when the acceleration of the vehicle 300 is within the first acceleration range P1(+) or within the second acceleration range P2(+), or when the deceleration is within the first deceleration range P1(−) or within the second deceleration range P2(−), the control controller/control unit 228R2 records the values detected by the acceleration sensor 316. The control controller/control unit 228R2 plots points corresponding to the recorded detection values on a coordinate system having a first axis representing the vehicle longitudinal direction acceleration and a second axis representing the vehicle vertical direction, thereby calculating a linear approximation. The control controller/control unit 228R2 calculates the linear approximation, for example, at the time when, while the vehicle 300 is moving, the values detected by the acceleration sensor 316 or the plotted values thereof in the first acceleration range P1(+), first deceleration range P1(−), the second acceleration range P2(+) and second deceleration range P2(−) are arranged.

The control controller/control unit 228R2 corrects the optical axis O and the reference value of the vehicle attitude angle θv based a variation in the slope of the calculated linear approximation at a given timing while the vehicle is moving. More specifically, the control controller/control unit 228R2 calculates an error component Δθe, which is a difference between the reference value of the vehicle attitude angle θv and a vehicle attitude angle θv obtained from the slope of the linear approximation (a ratio between the temporal change amount of acceleration in the vehicle longitudinal direction and the temporal change amount of acceleration in the vehicle vertical direction). For example, the control controller/control unit 228R2 calculates the accumulated value of variations in the slope of the linear approximation from the first time to the current time calculations to derive the vehicle attitude angle θv, and finds the error component Δθe from this vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4. Or, the control controller/control unit 228R2, similarly to the second exemplary embodiment, may obtain a vehicle attitude angle θv from the slopes of the previously stored reference linear approximation and the calculated linear approximation, and may find an error component Δθe from this vehicle attitude angle θv and the reference value of the vehicle attitude angle θv stored in the memory 228R4.

The control controller/control unit 228R2 corrects the reference value of the vehicle attitude angle θv such that the error component Δθe is reduced. In this case, the control controller/control unit 228R2, when the absolute value of the obtained the error component Δθe exceeds a threshold value θth (|Δθe|>θth), corrects the reference value of the vehicle attitude angle θv by a correction value θc. Also, the control controller/control unit 228R2 generates a control signal for adjusting the optical axis position by the correction value θc, thereby correcting the optical axis position. Here, the control controller/control unit 228R2 may also carry out the above-mentioned correction process, for example, just after the stop of the vehicle 300.

The “threshold value θth” and the “correction value θc” can be set in accordance with the resolution of the optical axis control, the detection accuracy of the error component Δθe, or the detection resolution of the vehicle attitude angle θv using a variation in the slope of the linear approximation. The threshold value θth is set within the range of the error that provides no obstacle to the optical axis control. The correction value θc is set, for example, based on the error that is caused by, of error main factors, an error factor having the smallest generation error value. Such error factor includes, for example, variations in the vehicle attitude under the same load condition, that is, variations in the suspension of the vehicle.

The correction value θc is smaller than the threshold value θth. Due to this, even when the detection accuracy of the error component Δθe is low, the reference value of the vehicle attitude angle θv can be made to approximate gradually to a correct value. For example, the resolution of the angle detection using variations in the slope of the linear approximation is 0.04°, while the threshold value θth is set for 0.1° and the correction value θc is set for 0.03° respectively. The “threshold value θth” and “correction value θc” can be set based on an experiment or simulation by a designer.

As described above, the plot range information has a set of the acceleration side range and deceleration side range. Due to such combination of the acceleration side range and deceleration side range, the error component of the vehicle attitude variations to be caused by acceleration and the error component of the vehicle attitude variations caused by deceleration can cancel each other. This makes it possible to calculate a linear approximation with higher accuracy. Also, the first acceleration range P1(+) and first deceleration range P1(−) as well as the second acceleration range P2(+) and second deceleration range P2(−) are set respectively such that the ranges of the magnitude (absolute values) of the acceleration and deceleration are equal to each other. Due to such setting, the error component of the vehicle attitude variations to be caused by acceleration and the error component of the vehicle attitude variations caused by deceleration can cancel each other. This makes it possible to calculate a linear approximation with further higher accuracy.

In this exemplary embodiment, the first acceleration range P1 (+) and first deceleration range P1 (−) are set such that they respectively provide a range of given gentle acceleration or deceleration. Also, the second acceleration range P2 (+) and second deceleration range P2 (−) are set respectively such that they respectively provide a range of given rapid acceleration or deceleration which is larger when compared with the first acceleration range P1 (+) and first deceleration range P1 (−). In this exemplary embodiment, since the plot range information has a set of gentle and rapid acceleration and deceleration ranges, when compared with a case employing only a set of gentle acceleration and deceleration or only a set of rapid acceleration and deceleration, a linear approximation can be calculated with higher accuracy.

Here, for the first acceleration range P1 (+) and first deceleration range P1 (−) as well as the second acceleration range P2 (+) and second deceleration range P2 (−), there may also be calculated linear approximations independently of each other and the respective correction processes may be carried out according to the slopes of the respective linear approximations. In this case, according to the calculation frequency or calculation accuracy of the set of the first acceleration range P1 (+) and first deceleration range P1 (−) as well as the set of the second acceleration range P2 (+) and second deceleration range P2 (−), the weight of correction may be different from each other, for example, the magnitude of the correction value θc may be varied. Or, the correction process may be carried out according to the average of the slopes of the linear approximations calculated respectively independently. Further, when, in the set of the first acceleration range P1 (+) and first deceleration range P1 (−) as well as the set of the second acceleration range P2 (+) and second deceleration range P2 (−), plots are arranged, a linear approximation may be calculated using these plots; and, when the plots are not ready in both sets within a given time, a linear approximation may be calculated using the plots of the set in which the plots are ready at the that time.

The plot range information may have only the set of the first acceleration range P1 (+) and first deceleration range P1 (−) or only the set of the second acceleration range P2 (+) and second deceleration range P2 (−). For example, the set of the first acceleration range P1 (+) and first deceleration range P1 (−) set in the gentle acceleration and deceleration range, when compared with the set of the second acceleration range P2 (+) and second deceleration range P2 (−) set in the rapid acceleration and deceleration range, has higher frequency that the values detected by the acceleration sensor 316 are included in this range while the vehicle is moving, thereby being able to increase the number of times of correction processes. The number of sets of the acceleration range and deceleration range contained in the plot range information may be three or more.

The first acceleration range P1 (+) and first deceleration range P1 (−) as well as the second acceleration range P2 (+) and second deceleration range P2 (−) may also be set such that the ranges of the magnitude of the acceleration or deceleration are equal to each other and also the ranges of the vehicle speed are equal to each other. In this case, since an error component caused by acceleration and an error component caused by deceleration can cancel each other, a linear approximation can be calculated with further higher accuracy. The range width of the acceleration and deceleration ranges, the magnitude of the acceleration and deceleration and the like can be set based on an experiment or simulation by a designer.

FIG. 7 is a flow chart of the auto-leveling control of the vehicle lamp system according to the third exemplary embodiment. This flow is executed repeatedly at a given timing by the irradiation controller 228R, more specifically, by the control controller/control unit 228R2, when an ignition is switched on, for example, in a state where an instruction for execution of the auto-leveling control mode is given by the light switch 304; and, when the ignition is turned off, this flow is ended.

The control controller/control unit 228R2 determines whether the vehicle is moving (S201). If it is determined that the vehicle is moving (S201; Y), the control unit 228R2 determines whether the plots of the values detected by the acceleration sensor 316 in the set of first acceleration range P1 (+) and first deceleration range P1 (−) as well as the set of second acceleration range P2 (+) and second deceleration range P2 (−) are ready (S202). When the plots are not ready (S202; N), the control controller/control unit 228R2 avoids the optical axis adjustment (S203) and ends this routine. When the plots are ready (S202; Y), the control controller/control unit 228R2 calculates a linear approximation (S204), and calculates an error component Δθe which is a difference between a vehicle attitude angle θv derived from the slope of the linear approximation and the reference value of a vehicle attitude angle θv stored in the memory 228R4 (S205).

The control controller/control unit 228R2 determines whether the absolute value of the error component Δθe exceeds the threshold value θth (S206). If it is determined that the absolute value of the error component Δθe exceeds the threshold value θth (S206; Y), the control unit 228R2 corrects the reference value of the vehicle attitude angle θv and optical axis position by the correction value θc (S207). After then, the control controller/control unit 228R2 avoids the optical axis adjustment with respect to a variation in the summed angle θ obtained from the value detected by the acceleration sensor 316 (S203) and ends this routine. If it is determined that the absolute value of the error component Δθe is equal to or less than the threshold value θth (S206; N), the control controller/control unit 228R2 avoids the optical axis adjustment without executing the correction process (S203) and ends this routine.

If it is determined that the vehicle is not moving (S201; N), the control controller/control unit 228R2 determines whether it is when the vehicle is stopped (S208). If it is determined that it is when the vehicle is stopped (S208; Y), the control controller/control unit 228R2 calculates the road surface angle θr (S209) and stores the calculated road surface angle θr as a new reference value (S210), avoids the optical axis adjustment (S203) and ends this routine. If it is determined that it is not when the vehicle is not stopped (S208; N), the control controller/control unit 228R2 calculates the vehicle attitude angle θv (S211) and determines whether a difference between the calculated vehicle attitude angle θv and the reference value of the vehicle attitude angle θv is equal to or more than a threshold (S212). If the difference is less than the threshold (S212; N), the control controller/control unit 228R2 avoids the optical axis adjustment (S203) and ends this routine. If the difference equal to or more than the threshold (S212; Y), the control controller/control unit 228R2 adjusts the optical axis position according to the calculated vehicle attitude angle θv (S213), stores the calculated vehicle attitude angle θv as a reference value (S214) and ends this routine.

As described above, in the vehicle lamp system 200 according to this exemplary embodiment, the control controller/control unit 228R2 calculates a linear approximation from the plots of the values detected by the acceleration sensor 316 when the acceleration of the vehicle 300 is within a given range and from the plots of the values detected by the acceleration sensor 316 when the deceleration of the vehicle 300 is within a given range. Therefore, an error component such as a vehicle attitude variation caused by the acceleration and an error component such as a vehicle attitude variation caused by the deceleration can cancel each other, thereby being able to calculate a linear approximation having a slope that is closer to the vehicle attitude angle θv.

Also, the control controller/control unit 228R2 carries out a correction process at the time when plots are obtained in the given acceleration range and deceleration range. In a control system configured such that a correction is carried out immediately after the vehicle stops by calculating a linear approximation from the values detected by the acceleration sensor 316 and recorded from the moving start to stop of the vehicle 300, if. If there is an error in the calculation of the vehicle attitude angle θv and optical axis adjustment while the vehicle is stopped after the correction, the vehicle 300 will move while containing such error. However, this exemplary embodiment can avoid such trouble.

Here, the vehicle lamp system 200 according to the above respective exemplary embodiments is a mode of the invention. This vehicle lamp system 200 includes the lamp unit 10 capable of adjusting its optical axis, acceleration sensor 316, and irradiation controllers 228L, 228R for controlling the lamp unit 10, while it carries out the above-mentioned auto-leveling control using the irradiation controllers 228L, 228R.

The other mode of the invention includes the irradiation controllers 228L, 228R respectively serving as control apparatus. The irradiation controllers 228L, 228R respectively include receivers 228L1, 228R1 for receiving vehicle longitudinal direction and vertical direction acceleration from the acceleration sensor 316, control controllers/control units 228L2, 228R2 for carrying out the above auto-leveling control, and transmitters 228L3, 228R3 for transmitting control signals generated by the control controllers/control units 228L2, 228R2 to a leveling controller 236. The irradiation controller 228 in the vehicle lamp system 200 corresponds to a controller in a broad sense, while the control controllers/control units 228L2, 228R2 in the irradiation controller 228 correspond to a controller in a narrow sense.

A further mode of the invention includes a method for controlling a vehicle lamp. This control method adjusts the optical axis of the lamp unit 10 based on a variation in the ratio between the temporal change amount of the vehicle longitudinal direction acceleration and the temporal change amount of the vehicle vertical direction acceleration during at least one of the acceleration and deceleration of the vehicle 300.

While the present invention has been described with reference to certain exemplary embodiments thereof, the scope of the present invention is not limited to the exemplary embodiments described above, and it will be understood by those skilled in the art that various changes and modifications, including combinations of features of different exemplary embodiments described above, may be made therein without departing from the scope of the present invention as defined by the appended claims.

For example, in the respective exemplary embodiments, the irradiation controller 228 may directly control the leveling actuator 226 serving as an optical axis adjusting portion, without a separate leveling controller 236. That is, the irradiation controller 228 may function as the leveling controller 236. The generation of a control signal for instruction of the optical axis adjustment in the above respective exemplary embodiments may also be carried out by the vehicle controller 302. That is, the vehicle controller 302 may serve as a controller for carrying out the auto-leveling control. In this case, the irradiation controller 228 controls the drive of the leveling actuator 226 according to an instruction from the vehicle controller 302.

In the first exemplary embodiment as well, similarly to the third exemplary embodiment, a correction process using a threshold value θth and a correction value θc may be carried out.

Claims

1. A vehicle lamp controller comprising:

a receiver configured to receive an acceleration information detected by an acceleration sensor;

a control unit configured to derive a vehicle longitudinal direction acceleration and a vehicle vertical direction acceleration from the acceleration information, and to generate a control signal for instructing an adjustment of an optical axis of a vehicle lamp, based on a variation in a ratio between a temporal change amount of the vehicle longitudinal direction acceleration and a temporal change amount of the vehicle vertical direction acceleration during at least one of an acceleration and a deceleration of a vehicle; and

a transmitter configured to transmit the control signal to an optical axis adjusting portion of the vehicle lamp.

2. The controller according to claim 1, wherein the control unit plots points corresponding to values detected by the acceleration sensor, over a time during at least one of the acceleration and the deceleration of the vehicle, on a coordinate system having a first axis representing the vehicle longitudinal direction acceleration and a second axis representing the vehicle vertical direction acceleration, and defines a slope of a straight line or a vector obtained from at least two of the points as the ratio.

3. The controller according to claim 2, wherein the control unit defines, as the ratio, the slope of the straight line or the vector obtained from the values detected by the acceleration sensor, the values including include values detected by the acceleration sensor while the acceleration of the vehicle is within a given range and values detected by the acceleration sensor while the deceleration of the vehicle is within a given range.

4. The controller according to claim 2, wherein the control unit obtains straight line or the vector is a linear approximation with respect to the points, and the control unit defines the slope of the linear approximation as the ratio.

5. The controller according claim 1, further comprising a memory,

wherein the control unit obtains acceleration information detected by the acceleration sensor comprises a summed angle including a first angle and a second angle from the acceleration information, the summed angle being an inclination angle of the vehicle with respect to a horizontal plane, the first angle being an inclination angle of a road surface with respect to the horizontal plane, and the second angle being an inclination angle of the vehicle with respect to the road surface, and

wherein a reference value of the first angle and a reference value of the second angle are stored in the memory,

wherein, when the summed angle varies while the vehicle is stopped, the control unit generates the control signal for instructing the adjustment of the optical axis of the vehicle lamp using the second angle, that is obtained from the summed angle and the reference value of the first angle, and stores the second angle in the memory as the reference value of the second angle,

wherein, when the summed angle varies while the vehicle is moving, the control unit does not generate the control signal for instructing the adjustment of the optical axis of the vehicle lamp or generates a control signal for maintaining a position of the optical axis, and when the vehicle stops, the control unit stores the first angle, that is obtained from the summed angle and the reference value of the second angle, in the memory as the reference value of the first angle, and

wherein, when the ratio varies, the control unit corrects the position of the optical axis of the vehicle lamp based on the variation in the ratio.

6. The controller according to claim 5, wherein the control unit calculates a difference between the reference value of the second angle and the second angle derived from the ratio, and corrects the reference value of the second angle such that the difference is reduced.

7. The controller according to claim 6, wherein, when the difference exceeds a threshold value, the control unit corrects the reference value of the second angle by a correction value that is smaller than the threshold value.

8. The controller according to claim 1, wherein the control unit obtains an inclination angle of the vehicle with respect to a road surface from the ratio and a reference value of the ratio, that is the reference value of the ratio obtained during at least one of the acceleration and the deceleration of the vehicle on a horizontal plane, and generates the control signal using the inclination angle of the vehicle with respect to the road surface.

9. The controller according to claim 1, wherein the acceleration information detected by the acceleration sensor comprises a summed angle including a first angle and a second angle from the acceleration information, the summed angle being an inclination angle of the vehicle with respect to a horizontal plane, the first angle being an inclination angle of a road surface with respect to the horizontal plane, and the second angle being an inclination angle of the vehicle with respect to the road surface.

10. The controller according to claim 1, wherein the control unit is configured to obtain an inclination angle of the vehicle with respect to a road surface based on the variation in the ratio between the temporal change amount of the vehicle longitudinal direction acceleration and the temporal change amount of the vehicle vertical direction acceleration.

11. A vehicle lamp system comprising:

a vehicle lamp having an adjustable optical axis;

an acceleration sensor; and

a controller configured to control the vehicle lamp,

wherein the controller comprises:

a receiver configured to receive an acceleration information detected by the acceleration sensor;

a control unit configured to derive a vehicle longitudinal direction acceleration and a vehicle vertical direction acceleration from the acceleration information, and to generate a control signal for instructing an adjustment of the optical axis of the vehicle lamp, based on a variation in a ratio between a temporal change amount of the vehicle longitudinal direction acceleration and a temporal change amount of the vehicle vertical direction acceleration during at least one of an acceleration and a deceleration of a vehicle; and

a transmitter configured to transmit the control signal to an optical axis adjusting portion of the vehicle lamp.

12. The vehicle lamp system according to claim 11, wherein the acceleration information detected by the acceleration sensor comprises a summed angle including a first angle and a second angle from the acceleration information, the summed angle being an inclination angle of the vehicle with respect to a horizontal plane, the first angle being an inclination angle of a road surface with respect to the horizontal plane, and the second angle being an inclination angle of the vehicle with respect to the road surface.

13. The vehicle lamp system according to claim 11, wherein the control unit is configured to obtain an inclination angle of the vehicle with respect to a road surface based on the variation in the ratio between the temporal change amount of the vehicle longitudinal direction acceleration and the temporal change amount of the vehicle vertical direction acceleration.

14. A vehicle lamp control method comprising;

obtaining an acceleration information detected by an acceleration sensor;

deriving a vehicle longitudinal direction acceleration and a vehicle vertical direction acceleration from the acceleration information;

calculating a variation in a ratio between a temporal change amount of the vehicle longitudinal direction acceleration and a temporal change amount of the vehicle vertical direction acceleration during at least one of an acceleration and a deceleration of a vehicle; and

adjusting an optical axis of a vehicle lamp based on the ratio.

15. The vehicle lamp control method according to claim 14, wherein the obtaining the acceleration information detected by the acceleration sensor comprises obtaining a summed angle including a first angle and a second angle from the acceleration information, the summed angle being an inclination angle of the vehicle with respect to a horizontal plane, the first angle being an inclination angle of a road surface with respect to the horizontal plane, and the second angle being an inclination angle of the vehicle with respect to the road surface.

16. The vehicle lamp control method according to claim 14, further comprising obtaining an inclination angle of the vehicle with respect to a road surface based on the variation in the ratio between the temporal change amount of the vehicle longitudinal direction acceleration and the temporal change amount of the vehicle vertical direction acceleration.