Control system and method for adjusting brightness of projector according to temperature change of vehicle lamp

Abstract

The invention provides a control system and method for adjusting the brightness of a projector according to the temperature change of a vehicle lamp, and relates to the technical field of vehicle-mounted projection. Comprising the steps of collecting temperature data of a constant-current chip in real time; predicting the temperature value at the current moment based on the temperature state at the previous moment and the dynamic characteristics of the system; updating the covariance matrix based on the state covariance and the process noise covariance matrix at the previous moment; calculating Kalman gain based on the measurement matrix, the updated covariance matrix and the measurement noise covariance matrix; the estimated temperature at the current moment is calculated based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit and the temperature data of the constant current chip; and based on the estimated temperature output by the state updating unit and the brightness signal provided by the automobile host, the driving current output to the constant current chip is adjusted through double-loop PID control. The problems of brightness jump and flicker caused by hardware threshold triggering in the prior art are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of in-vehicle projection, and particularly relates to a control system and method for adjusting the brightness of a projector according to the temperature change of a vehicle lamp. Background Art

[0002] Currently, the brightness of an in-vehicle projector is controlled by adjusting the PWM duty cycle of a constant current chip according to the brightness sent by the vehicle host. In actual use, the constant current chip is greatly affected by temperature. According to the technical specifications of the constant current chip, when the temperature exceeds 110 degrees, the output of the constant current chip will continuously jump, resulting in the projector flickering continuously. Based on this, in the prior art, a temperature feedback circuit is usually used to collect the temperature of the constant current chip, and the output current is reduced when the temperature exceeds the threshold. This leads to the following technical problems in the prior art:

[0003] (1) Limitation of control logic: Only realizing current regulation through a hardware circuit belongs to passive regulation based on hardware, mostly simple threshold triggering, and it is difficult to achieve continuous and smooth parameter optimization.

[0004] (2) Insufficient adjustment accuracy: Unable to dynamically adjust the current change rate according to the temperature gradient, with obvious deficiencies in control accuracy.

[0005] (3) Single application scenario: Applied to the current control of general chips, such as power management chips, not adapted to special scenarios such as in-vehicle projectors, and unable to solve specific problems in such scenarios.

[0006] (4) Problems of brightness jump and flicker: Only able to solve the functional problem of "current jump when the temperature is too high", unable to achieve "soft brightness gradient", and it is difficult to meet the higher requirements of users for experience.

[0007] (5) Hysteresis: Dependent on the fixed threshold of the hardware circuit, the adjustment method is relatively passive, unable to adjust in advance according to the temperature change trend, and there is a situation of adjustment hysteresis.

[0008] The above problems need to be solved urgently. Summary of the Invention

[0009] The purpose of the present invention is to overcome at least one technical problem existing in the prior art, and provide a control system and method for adjusting the brightness of a projector according to the temperature change of a vehicle lamp.

[0010] On the one hand, an embodiment of the present invention provides a control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp. The control system includes: a vehicle host, a micro-control unit, a constant current chip, and an in-vehicle projector; the vehicle host is used to provide a brightness signal and a video source; the micro-control unit integrates a temperature acquisition unit, a Kalman filter unit, and a brightness control unit; the temperature acquisition unit is used to collect the temperature data of the constant current chip in real time; the Kalman filter unit integrates a state prediction unit, a covariance prediction unit, a measurement value fusion unit, and a state update unit; the state prediction unit is used to predict the temperature value at the current moment based on the temperature state at the previous moment and the system dynamic characteristics; the covariance prediction unit is used to update the covariance matrix based on the state covariance at the previous moment and the process noise covariance matrix; the measurement value fusion unit is used to calculate the Kalman gain based on the measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix; the state update unit is used to calculate the estimated temperature at the current moment based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit, and the temperature data of the constant current chip; the brightness control unit is used to adjust the drive current output to the constant current chip through double-loop PID control based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host; the in-vehicle projector is used to project based on the current value output by the constant current chip and the video source sent by the vehicle host.

[0011] Further, the state prediction unit integrates a state prediction formula, including:

[0012]

[0013] In the formula, represents the predicted state estimate value at time k, x k-1 is the temperature state at time k - 1, A is the state transition matrix, B is the control input matrix, u k is the external control input at time k.

[0014] Further, the covariance prediction unit integrates a covariance prediction formula, including:

[0015] p k | k-1 = A·p k-1 ·A T + Q;

[0016]

[0017] In the formula, p k|k-1 represents the predicted state covariance at time k, p k-1 represents the state covariance at time k - 1, A is the state transition matrix, and Q is the process noise covariance matrix.

[0018] Further, a Kalman gain calculation formula is integrated in the measurement value fusion unit, including:

[0019] K k = p k|k-1 ·H T ·(H·p k|k-1 ·H T + R) -1 ;

[0020] In the formula, K k is the Kalman gain at time k, H is the measurement matrix, and R is the measurement noise covariance matrix.

[0021] Further, a state update formula is integrated in the state update unit, including:

[0022]

[0023] In the formula, x k is the estimated temperature at time k, and z k is the temperature data of the constant current chip.

[0024] Further, a covariance update unit is also integrated in the Kalman filter unit, which is used to update the covariance matrix obtained by the covariance prediction unit based on the Kalman gain, so that the covariance gradually converges with iteration, including:

[0025] p k = (I - K k ·H)·p kk-1 ;

[0026] In the formula, I is the identity matrix.

[0027] Further, a temperature trend prediction and early adjustment unit is also integrated in the Kalman filter unit, which is used to predict the temperature value in a future preset time period in advance through Kalman filtering and send a brightness adjustment control signal to the brightness control unit in advance for a preset time period when the temperature change rate exceeds a preset change rate threshold.

[0028] Further, the temperature trend prediction and early adjustment unit is also used for:

[0029] Obtaining a temperature change rate based on a preset temperature change rate calculation formula, including:

[0030] When the temperature change rate exceeds the preset change rate threshold, obtaining the number of iterations for the state prediction unit based on the future prediction time period;

[0031] Iteratively obtaining the temperature estimated value after the prediction time period based on the number of iterations.

[0032] Further, in the dual-loop PID control, the outer loop is a temperature-brightness mapping loop, and the inner loop is a current loop;

[0033] The outer loop is used to output a target current corresponding to the estimated temperature through a preset three-dimensional mapping model based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host;

[0034] The inner loop is used to adjust the driving current based on the target current and the actual current value through the PID algorithm.

[0035] In a second aspect, an embodiment of the present invention provides a control method for adjusting the brightness of a projector according to the temperature change of a vehicle headlight, which is applied to the control system for adjusting the brightness of a projector according to the temperature change of a vehicle headlight as described above. The control method includes: obtaining a brightness signal and a video source provided by a vehicle host; collecting temperature data of the constant current chip in real time through a temperature acquisition unit; predicting the temperature value at the current moment by a state prediction unit based on the temperature state at the previous moment and the system dynamic characteristics; updating the covariance matrix by a covariance prediction unit based on the state covariance at the previous moment and the process noise covariance matrix; calculating a Kalman gain by a measurement value fusion unit based on a measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix; calculating the estimated temperature at the current moment by a state update unit based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit, and the temperature data of the constant current chip; adjusting the driving current output to the constant current chip through dual-loop PID control by a brightness control unit based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host; and the in-vehicle projector performing projection based on the current value output by the constant current chip and the video source sent by the vehicle host.

[0036] In yet another aspect, the present invention further provides a computer-readable storage medium, in which one or more instructions are stored, and the computer instructions are used to cause the computer to execute the above control method for adjusting the brightness of a projector according to the temperature change of a vehicle headlight.

[0037] In still another aspect, the present invention provides an electronic device, including: a memory and a processor; at least one program instruction is stored in the memory; and the processor realizes the above control method for adjusting the brightness of a projector according to the temperature change of a vehicle headlight by loading and executing the at least one program instruction.

[0038] The beneficial effects of the present invention are:

[0039] (1) Advance prediction and rapid response: By establishing a temperature noise model through Kalman filtering, the current can be adjusted N seconds in advance before a high-temperature jump, reducing the temperature-current adjustment delay from ≥500 ms in the prior art to ≤100 ms, and solving the problem of hysteresis in hardware feedback.

[0040] (2) Brightness stability under high-temperature conditions: For the high-temperature environment above 110 °C near the vehicle engine compartment, by dynamically adjusting the current change rate through the temperature gradient, "soft and gradual brightness change" is achieved, and the jump cannot be detected by the naked eye, solving the non-linear problem of LED light source brightness attenuation in the traditional solution.

[0041] (3) Vibration and noise resistance and wide-temperature adaptability: Through Kalman filtering, by adaptively adjusting the noise covariance matrix, the temperature sampling error is reduced from ±2 °C to ±0.5 °C, and at the same time, the chip operating temperature range is extended to -20 °C to 125 °C, adapting to the high-vibration and wide-temperature fluctuation requirements of the vehicle environment.

[0042] (4) User experience and function optimization: Eliminating the brightness jump and flicker problems caused by hardware threshold triggering in the prior art, achieving the "zero jump" effect, and at the same time balancing the contradiction between brightness smoothness and response speed, improving the display quality of the vehicle-mounted projector.

[0043] (5) Synergistic effect of cross-domain technology integration: Combining Kalman filtering (state prediction in the navigation field) with dual-loop PID (industrial control) to construct an intelligent logic chain of "temperature acquisition-noise filtering-hierarchical control", breaking through the passive adjustment limitation of traditional hardware feedback, and forming a technical effect of "1 + 1 > 2". Brief Description of the Drawings

[0044] The present invention will be further described below in conjunction with the drawings and embodiments.

[0045] Figure 1 Schematic diagram of a control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp provided in Embodiment 1 of the present invention.

[0046] Figure 2 Another schematic diagram of a control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp provided in Embodiment 1 of the present invention.

[0047] Figure 3 Flowchart of a control method for adjusting the brightness of a projector according to the temperature change of a vehicle lamp provided in Embodiment 2 of the present invention.

[0048] Figure 4 Partial block diagram of an electronic device provided in Embodiment 4 of the present invention. Detailed Embodiments

[0049] Before discussing the exemplary embodiments in more detail, it should be noted that some exemplary embodiments are described as processes or methods depicted as flowcharts. Although the flowcharts depict the operations as sequential processes, many of the operations can be implemented in parallel, concurrently, or simultaneously. In addition, the order of the operations can be rearranged. The process can be terminated when its operations are completed, but it can also have additional steps not included in the figures. The process can correspond to a method, function, procedure, subroutine, subprogram, and so on.

[0050] It should be understood that although terms such as "first" and "second" may be used herein to describe various units, these units should not be limited by these terms. These terms are only used to distinguish one unit from another. For example, without departing from the scope of the exemplary embodiments, the first unit can be referred to as the second unit, and similarly, the second unit can be referred to as the first unit. The term "and / or" used herein includes any and all combinations of one or more of the listed associated items.

[0051] The present invention will now be described in detail with reference to the accompanying drawings. This figure is a simplified schematic diagram, which only schematically illustrates the basic structure of the present invention, so it only shows the components related to the present invention.

[0052] Embodiment 1

[0053] For ease of understanding, the inventive concept is described as a whole before the detailed description of the embodiments of the present invention: The present invention provides a control system for adjusting the brightness of a projector according to the temperature change of a vehicle headlight, including: a vehicle host, a micro control unit, a constant current chip, and an in-vehicle projector; the vehicle host sends a brightness signal to the micro control unit and sends a video source to the projector at the same time. The micro control unit collects the temperature of the constant current chip, receives the brightness signal sent by the vehicle host, and uses the Kalman filtering algorithm to obtain the actual temperature of the constant current chip after removing noise. After the micro control unit obtains the current temperature and current, it controls the current of the constant current chip through a double-loop PID control algorithm to light up the LED lamp board of the projector and realize image projection. The technical key point of the present invention is to use the Kalman filtering algorithm to obtain the temperature of the constant current chip and control the current through the double-loop PID algorithm, so as to realize the precise adjustment of the projector brightness, and finally make it impossible for the user's naked eyes to detect the brightness jump and feel the projector flicker.

[0054] The specific implementation is as follows:

[0055] As Figure 1 shown, it is a schematic structural diagram of a control system for adjusting the brightness of a projector according to the temperature change of a vehicle headlight provided by the present invention.

[0056] As an example, the control system includes: a vehicle host 1, a microcontroller unit 2, a constant current chip 3, and an in-vehicle projector 4; the vehicle host 1 is used to provide a brightness signal and a video source; the microcontroller unit 2 integrates a temperature acquisition unit 20, a Kalman filter unit 21, and a brightness control unit 22; the temperature acquisition unit 20 is used to collect the temperature data of the constant current chip 3 in real time; the Kalman filter unit 21 integrates a state prediction unit 210, a covariance prediction unit 211, a measurement value fusion unit 212, and a state update unit 213; the state prediction unit 210 is used to predict the temperature value at the current moment based on the temperature state at the previous moment and the system dynamic characteristics; the covariance prediction unit 211 is used to update the covariance matrix based on the state covariance at the previous moment and the process noise covariance matrix; the measurement value fusion unit 212 is used to calculate the Kalman gain based on the measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix; the state update unit 213 is used to calculate the estimated temperature at the current moment based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit 210, and the temperature data of the constant current chip 3; the brightness control unit 22 is used to adjust the drive current output to the constant current chip 3 through double-loop PID control based on the estimated temperature output by the state update unit 213 and the brightness signal provided by the vehicle host; the in-vehicle projector 4 is used to project based on the current value output by the constant current chip 3 and the video source sent by the vehicle host 1.

[0057] In some feasible embodiments, the state prediction unit 210 integrates a state prediction formula, including:

[0058]

[0059] In the formula, represents the predicted state estimate value at time k, x k-1 is the temperature state at time k - 1, A is the state transition matrix, B is the control input matrix, u k is the external control input at time k.

[0060] Preferably, when k = 1, x0 is the initial temperature sampling value of the sensor, x k-1 is the predicted temperature estimate value obtained after the (k - 1)th iteration, which is the result corrected by the Kalman filter. A is the state transition matrix, which is autocorrelated with temperature, that is, its value is related to temperature. When the temperature is in the low temperature region (-20°C - 25°C), the value of A is 0.995; when the temperature is in the high temperature region (90°C - 125°C), the value of A is 0.98; when the temperature is in the middle temperature region (25°C - 90°C), where, T k ∈(25°C - 90°C).

[0061] Preferably, since the constant current chip may be equipped with a temperature control system itself, an active adjustment signal will be generated, such as controlling the temperature by adjusting the input current or starting a heat dissipation device. That is, the input u is controlled. k Let P be the chip power consumption. Since this action will have a certain impact on the temperature, in order to make the subsequent temperature estimation more accurate, the dynamic characteristics of the system need to be considered here. Set B to -0.3 °C / V, which means that for every 1V increase in the fan voltage, the temperature drops by 0.3 °C. That is, on the basis of the natural change of the temperature, the active temperature control effect of the fan heat dissipation is superimposed to make the predicted value closer to the actual temperature.

[0062] In some feasible embodiments, a covariance prediction formula is integrated in the covariance prediction unit 211, including:

[0063] p k|k-1 = A·p k-1 ·A T + Q;

[0064]

[0065] In the formula, p kk-1 represents the predicted state covariance at time k, p k-1 represents the state covariance at time k-1, A is the state transition matrix, and Q is the process noise covariance matrix.

[0066] Preferably, during the vehicle operation, the in-vehicle CAN bus transmits the vehicle vibration acceleration in real time, so as to dynamically adjust the process noise covariance matrix based on this. By adaptively adjusting the specific value of the process noise covariance matrix according to the vibration acceleration in the in-vehicle scenario, the noise parameters can be adjusted in real time according to the environmental changes, making the model more in line with the real physical process and avoiding the estimation deviation caused by fixed parameters; when the environmental interference intensifies (such as severe vibration, high-temperature noise), the adaptive mechanism will automatically increase the noise weight, enabling the filtering algorithm to reduce the dependence on "unreliable predictions" and instead correcting the results through measurement values, avoiding the estimation failure caused by model errors; by dynamically adjusting the noise covariance, the Kalman gain can reasonably allocate the weights of prediction and measurement in different scenarios, enabling the temperature estimation to not only follow the dynamic changes but also suppress the sudden noise interference, ultimately improving the accuracy and stability of the long-term estimation.

[0067] In some feasible embodiments, a Kalman gain calculation formula is integrated in the measurement value fusion unit 212, including:

[0068] K k = p kk-1 ·H T ·(H·p kk-1 ·H T + R)-1 ;

[0069] In the formula, K k is the Kalman gain at time k, H is the measurement matrix, and R is the measurement noise covariance matrix. Among them, since the temperature is directly measurable, H is taken as 1.

[0070] Preferably, R represents the covariance of the sensor measurement noise, reflecting the deviation of the measured temperature z k from the true temperature x k . The larger R is, the more significant the sensor noise is. The Kalman filter will reduce the weight of the measured value and rely more on the predicted value. In this embodiment, R is dynamically calculated. For example, when the temperature x k > 25 °C, R is positively correlated with the temperature, and R = 0.5 °C 2 + 0.015 °C 2 / °C·(x k - 25 °C); when x k ≤ 25 °C, a fixed value R = 0.5 °C is taken 2 . By dynamically adjusting the value of R, the characteristics of the thermistor can be better adapted. For example, the resistance-temperature of the thermistor linearly decreases and the noise increases in the high-temperature region. By dynamically adjusting the value of R, the Kalman gain K k dynamically decreases, avoiding the interference of the high-temperature region noise on the filtering result. At the same time, it also avoids the situation where the traditional model with a fixed R = 2 °C 2 may lead to prediction lag due to overestimating the noise.

[0071] In some feasible embodiments, a state update formula is integrated in the state update unit 213, including:

[0072]

[0073] In the formula, x k is the estimated temperature at time k, and z k is the temperature data of the constant current chip. That is, the predicted value is corrected by the Kalman gain to obtain the optimal estimated temperature x k . Among them, z k is the sensor measured temperature value (including noise).

[0074] Combined with Figure 2 shown, in some feasible embodiments, a covariance update unit 214 is further integrated in the Kalman filter unit, which is used to update the covariance matrix obtained by the covariance prediction unit based on the Kalman gain, so that the covariance gradually converges with iteration, including:

[0075] p k = (I - K k ·H)·p k|k-1 ;

[0076] In the formula, I is the identity matrix. That is, by updating p kk-1 to p k in the next iteration process, the uncertainty of the prediction at the next moment is optimized, so that the covariance p k gradually converges with the iteration, and the temperature estimation accuracy is improved.

[0077] In some feasible embodiments, a temperature trend prediction and early adjustment unit 215 is further integrated in the Kalman filter unit 21, which is used to predict the temperature value in a future preset time period in advance through Kalman filtering and send a brightness adjustment control signal to the brightness control unit 22 in advance when the temperature change rate exceeds a preset change rate threshold.

[0078] Preferably, the temperature trend prediction and early adjustment unit 214 is further used for: obtaining the temperature change rate based on a preset temperature change rate calculation formula, including: When the temperature change rate exceeds the preset change rate threshold, obtaining the number of iterations for the state prediction unit based on the future prediction time period; iteratively obtaining the temperature estimation value after the prediction time period based on the number of iterations.

[0079] Specifically, at a certain moment k, if the temperature x k of the constant current chip is 50 °C, and the chip load suddenly increases at this time, resulting in a temperature change rate greater than the preset change rate threshold of 0.4 °C / ms, it is necessary to predict the temperature trend in the future 0.3 s (300 ms), that is, the entire process of the above Kalman filtering needs to be iterated 300 times. Since the power consumption characteristics (B parameter) and (A parameter) of the chip are combined during the iteration, the temperature trend can be predicted in advance. In this way, when the temperature changes too fast, the subsequent current control is carried out 0.3 s in advance, and through the mechanism of predicting the future temperature + early intervention, the traditional passive response is changed to active prevention.

[0080] It can be seen that the above Kalman filtering is not simply noise reduction in the embodiment, but constructs the basis of temperature intelligent control through "state prediction + dynamic optimization", converts the noise data collected by the hardware into predictable and adjustable dynamic signals, provides accurate temperature input for the subsequent double-loop PID control, and finally realizes high-precision control in a wide temperature range.

[0081] In some feasible embodiments, the outer loop of the double-loop PID control is a temperature-brightness mapping loop, and the inner loop is a current loop; the outer loop is used to output the target current corresponding to the estimated temperature based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host through a preset three-dimensional mapping model; the inner loop is used to adjust the drive current based on the target current and the actual current value through the PID algorithm.

[0082] Preferably, the double-loop PID consists of an inner loop (current loop) and an outer loop (temperature-brightness mapping loop), and the two are in a nested relationship. The three-dimensional mapping model is the corresponding relationship of temperature-current-brightness, and this three-dimensional mapping model is a preset model obtained after training with a large amount of data. It breaks through the traditional two-dimensional (temperature-current) model, realizes a gentle gradient change in brightness (for example, when the temperature rises by 10 °C, the current adjustment slope decreases by 20%), and eliminates the jump that can be detected by the naked eye.

[0083] Specifically, the outer loop finds the target current value corresponding to it in the three-dimensional mapping model according to the estimated temperature output by the Kalman filter unit 21 and the brightness signal provided by the vehicle host, solving the non-linear problem in a wide temperature range. The inner loop is used to directly control the actuator. Specific example, inner loop parameters: normal temperature range (25 °C to 90 °C): K p1 = 1.0, K i1 = 0.3, K d1 = 0.08; high temperature range (>90 °C): K p1 Automatically increased to 1.3 (to speed up the current adjustment speed), with differential limiting added (to avoid high-frequency noise interference). Outer loop (temperature-current mapping loop): segmented parameters: when the chip temperature < set value (such as 80 °C): K p2 = 1.5 (rapid temperature rise), integral coefficient K i2 = 0.5; when the chip temperature is close to the set value: K p2 = 0.6 (smooth adjustment), with anti-overshoot damping coefficient β = 0.4 added.

[0084] To verify the effect of the parameter settings in this embodiment, a test platform was built, including:

[0085] Test equipment: vehicle-mounted constant temperature chip (rated power 30W, operating temperature -40 °C to 125 °C), placed in an environmental test chamber (temperature control accuracy ±0.5 °C), equipped with a vibration table (simulating vehicle bump conditions).

[0086] Comparison scheme: Traditional scheme: hardware PID temperature control circuit (fixed parameters, no prediction function); This scheme: Kalman filter + double-loop PID intelligent control.

[0087] Key test results: High temperature stability test (chip set temperature 90 °C, ambient temperature 120 °C):

[0088] Traditional scheme: Chip temperature fluctuates between 88 °C and 93 °C, current fluctuates ±5%, there is a risk of thermal runaway;

[0089] This scheme: After Kalman filtering, the temperature is stable at 90.2 °C ± 0.8 °C, and the current fluctuation ≤ ±0.5%, meeting the constant temperature requirement.

[0090] Temperature sudden drop response (chip temperature 90°C → 60°C, cooling rate 2°C / s):

[0091] Traditional solution: Current regulation delay is 400 ms, chip temperature overshoots to 58°C, and recovery time > 2 seconds;

[0092] This solution: Predicts and adjusts the current 200 ms in advance, delay ≤ 80 ms, temperature smoothly drops to 60°C (overshoot < 1°C), and recovery time < 500 ms.

[0093] It can be seen that this embodiment solves the temperature fluctuation problem of in-vehicle constant temperature chips in vibration and wide-temperature environments through "dynamic noise filtering + intelligent predictive control". Compared with the traditional hardware solution, the temperature control accuracy is improved by more than 60%, and the current regulation delay is shortened by 80%.

[0094] In the above embodiment, through the software algorithm innovation of "Kalman filter prediction + double-loop PID adaptive control", it breaks through the "threshold trigger" limitation of the existing hardware feedback, and achieves a double breakthrough in control accuracy and user experience in the wide-temperature range and high-vibration scenarios of in-vehicle projectors. Breakthroughs are achieved in aspects such as temperature control accuracy, dynamic response speed, anti-interference ability, and system reliability. In particular, it solves the influence of complex factors such as vibration, wide temperature, and power supply fluctuations in the in-vehicle environment on the chip temperature, provides an efficient solution for the stable operation of constant current chips in scenarios such as in-vehicle electronics and new energy vehicles, and has significant technical advantages and engineering application value compared with traditional solutions.

[0095] It is worth mentioning that each module involved in this embodiment is a logic unit. In actual applications, a logic unit can be a physical unit, a part of a physical unit, or a combination of multiple physical units. In addition, in order to highlight the innovative part of the present invention, units that are not closely related to solving the technical problems proposed by the present invention are not introduced in this embodiment, but this does not mean that there are no other units in this embodiment.

[0096] Embodiment 2

[0097] Please refer to Figure 3 , this embodiment provides a control method flowchart for adjusting the brightness of a projector according to the temperature change of a vehicle lamp.

[0098] As an example, the method is applied to the control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp described in Embodiment 1, and the control method includes:

[0099] S1. Obtain the brightness signal and video source provided by the vehicle host.

[0100] S2. Real-time collect the temperature data of the constant current chip through the temperature acquisition unit.

[0101] S3. The state prediction unit predicts the temperature value at the current moment based on the temperature state at the previous moment and the system dynamic characteristics.

[0102] S4. The covariance prediction unit updates the covariance matrix based on the state covariance at the previous moment and the process noise covariance matrix.

[0103] S5. The measurement value fusion unit calculates the Kalman gain based on the measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix.

[0104] S6. The state update unit calculates the estimated temperature at the current moment based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit, and the temperature data of the constant current chip.

[0105] S7. The brightness control unit adjusts the drive current output to the constant current chip through dual-loop PID control based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host.

[0106] S8. The in-vehicle projector projects based on the current value output by the constant current chip and the video source sent by the vehicle host.

[0107] It is not difficult to find that this embodiment is a method embodiment corresponding to the first embodiment, and this embodiment can be implemented in cooperation with the first embodiment. The relevant technical details mentioned in the first embodiment are still valid in this embodiment. To avoid repetition, they are not elaborated here. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied in the first embodiment.

[0108] Embodiment 3

[0109] The embodiment of the present invention also proposes a storage medium, on which a control method for adjusting the brightness of the projector according to the temperature change of the vehicle lamp is stored. When the control program for adjusting the brightness of the projector according to the temperature change of the vehicle lamp is executed by a processor, the steps of the control method for adjusting the brightness of the projector according to the temperature change of the vehicle lamp as described above are realized. Since this storage medium adopts all the technical solutions of the above-mentioned all embodiments, it has at least all the beneficial effects brought by the technical solutions of the above-mentioned embodiments, and will not be elaborated here one by one.

[0110] Embodiment 4

[0111] Please refer to Figure 4, an embodiment of the present invention further provides an electronic device, including: a memory and a processor; at least one program instruction is stored in the memory; the processor loads and executes the at least one program instruction to implement the control method for adjusting the brightness of the projector according to the change of the headlight temperature provided in Embodiment 2.

[0112] The memory 702 and the processor 701 are connected in a bus manner. The bus may include any number of interconnected buses and bridges, and the bus connects various circuits of one or more processors 701 and the memory 702 together. The bus may also connect various other circuits such as peripheral devices, voltage regulators, and power management circuits, which are well known in the art, so they will not be further described herein. The bus interface provides an interface between the bus and the transceiver. The transceiver may be one component or multiple components, such as multiple receivers and transmitters, and provides a unit for communicating with various other devices on the transmission medium. The data processed by the processor 701 is transmitted on the wireless medium through the antenna. Further, the antenna also receives data and transmits the data to the processor 701.

[0113] The processor 701 is responsible for managing the bus and general processing, and can also provide various functions, including timing, peripheral interface, voltage regulation, power management, and other control functions. The memory 702 can be used to store the data used by the processor 701 when executing operations.

[0114] The above are only embodiments of the present invention. Common knowledge such as specific structures and characteristics known in the art are not described in detail herein. Those of ordinary skill in the art know all the common technical knowledge in the technical field to which the invention belongs before the application date or the priority date, can know all the prior art in this field, and have the ability to apply the conventional experimental means before this date. Those of ordinary skill in the art can, under the inspiration given in this application, combine their own abilities to complete and implement this solution. Some typical well-known structures or well-known methods should not be an obstacle for those of ordinary skill in the art to implement this application. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners described in the specification can be used to interpret the content of the claims.

Claims

1. A control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp, characterized in that, The control system includes: a vehicle host, a microcontroller unit, a constant current chip, and an in-vehicle projector; The vehicle host is used to provide a brightness signal and a video source; The microcontroller unit integrates a temperature acquisition unit, a Kalman filter unit, and a brightness control unit; The temperature acquisition unit is used to collect the temperature data of the constant current chip in real time; The Kalman filter unit integrates a state prediction unit, a covariance prediction unit, a measurement value fusion unit, and a state update unit; The state prediction unit is used to predict the temperature value at the current moment based on the temperature state at the previous moment and the system dynamic characteristics; The covariance prediction unit is used to update the covariance matrix based on the state covariance at the previous moment and the process noise covariance matrix; The measurement value fusion unit is used to calculate the Kalman gain based on the measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix; The state update unit is used to calculate the estimated temperature at the current moment based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit, and the temperature data of the constant current chip; The brightness control unit is used to adjust the drive current output to the constant current chip through dual-loop PID control based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host; The in-vehicle projector is used to project based on the current value output by the constant current chip and the video source sent by the vehicle host.

2. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 1, wherein The state prediction unit integrates a state prediction formula, including: wherein, represents the predicted state estimate at time k, x k-1 is the temperature state at time k-1 State, A is the state transition matrix, B is the control input matrix, and u k is the external control input at time k.

3. The control system for adjusting the brightness of the projector according to the temperature change of the vehicle lamp according to claim 2, wherein The covariance prediction unit integrates a covariance prediction formula, including: p k|k-1 = A·p k-1 ·A T + Q; where, p k|k-1 denotes the predicted state covariance at time k, and p k-1 denotes the state covariance at time k-1, A is the state transition matrix, and Q is the process noise covariance matrix.

4. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 3, characterized in that The measurement value fusion unit integrates a Kalman gain calculation formula, including: K k = p k|k-1 · H T · (H · p kk-1 · H T + R) -1 ; where K k is the Kalman gain at time k, H is the measurement matrix, and R is the measurement noise covariance matrix.

5. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 4, characterized in that, The state update unit integrates a state update formula, including: where x k is the estimated temperature at time k, and z k is the temperature data of the constant current chip.

6. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 5, characterized in that The Kalman filter unit also integrates a covariance update unit, which is used to update the covariance matrix obtained by the covariance prediction unit based on the Kalman gain, so that the covariance gradually converges with iteration, including: p k = (I - K k · H) · p k | k-1 ; In the formula, I is the identity matrix.

7. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 1, characterized in that, The Kalman filter unit also integrates a temperature trend prediction and early adjustment unit, which is used to predict the temperature value in a future preset time period in advance through Kalman filtering and send a brightness adjustment control signal to the brightness control unit in advance when the temperature change rate exceeds a preset change rate threshold.

8. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 7, characterized in that The temperature trend prediction and early adjustment unit is also used for: Obtaining a temperature change rate based on a preset temperature change rate calculation formula, including: When the temperature change rate exceeds the preset change rate threshold, obtaining the iteration times for the state prediction unit based on the future prediction time period; Iteratively obtaining the temperature estimated value after the prediction time period based on the iteration times.

9. The control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp according to claim 1, characterized in that The outer loop of the dual-loop PID control is a temperature-brightness mapping loop, and the inner loop is a current loop; The outer loop is used to output the target current corresponding to the estimated temperature through a preset three-dimensional mapping model based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host; The inner loop is used to adjust the drive current through the PID algorithm based on the target current and the actual current value.

10. A control method for adjusting the brightness of a projector according to the temperature change of a vehicle lamp, which is applied to the control system for adjusting the brightness of a projector according to the temperature change of a vehicle lamp described in any one of claims 1-9, characterized in that, The control method includes: Obtaining the brightness signal and video source provided by the vehicle host; Collecting the temperature data of the constant current chip in real time through the temperature acquisition unit; The temperature value at the current moment is predicted by the state prediction unit based on the temperature state at the previous moment and the system dynamic characteristics; The covariance matrix is updated by the covariance prediction unit based on the state covariance at the previous moment and the process noise covariance matrix; The Kalman gain is calculated by the measurement value fusion unit based on the measurement matrix, the updated covariance matrix, and the measurement noise covariance matrix; The estimated temperature at the current moment is calculated by the state update unit based on the Kalman gain, the predicted temperature value at the current moment output by the state prediction unit, and the temperature data of the constant current chip; The driving current output to the constant current chip is adjusted by the brightness control unit based on the estimated temperature output by the state update unit and the brightness signal provided by the vehicle host through dual-loop PID control; The in-vehicle projector projects based on the current value output by the constant current chip and the video source sent by the vehicle host.

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