Vehicle suspension speed-variable height closed-loop control method based on height change rate

Abstract

This invention discloses a closed-loop control method for vehicle suspension height adjustment based on the height change rate. During the height-controlled rise process via suspension control, as the vehicle ascends from its lowest height to the target height, high-speed data is collected in real time and the height change rate is calculated. Based on this rate, the rotational speed of the hydraulic pump is adjusted in real time to raise the vehicle to the target height. The advantages of this invention are: reducing or eliminating overshoot during the rise phase of the suspension's rhythmic control, thus improving the accuracy and reliability of the control.

Description

Technical Field

[0001] This invention relates to the field of active suspension control for automobiles, and in particular to a closed-loop control method for vehicle suspension with variable speed and height based on the rate of change of height. Background Technology

[0002] With the development of intelligent automotive technology, modern consumers have increasingly higher demands for cars. Active hydraulic suspension not only flexibly adapts to different driving scenarios and needs but also enhances driving pleasure and improves the daily driving experience. In active hydraulic suspension, each wheel end is equipped with an independent power source, actively exerting force to resist road surface damage. When dealing with complex road conditions, it exhibits superior adaptability and response speed, even achieving zero bumps, zero roll, and zero pitch, making daily rides more comfortable and extreme driving control more stable.

[0003] Based on active suspension control, vehicle rhythm control can be achieved, creating an experience similar to dancing with up-and-down movements. The underlying capability of this "car dancing" is that the suspension must be able to quickly adjust the vehicle's height and precisely coordinate the movement of each wheel. The dancing function is not merely a technological innovation; it also embodies the diversified development trend of future intelligent vehicles, endowing cars with greater social and entertainment value. In the future, with continuous technological advancements, the dancing function may showcase its rich possibilities in an even wider range of scenarios.

[0004] Currently, common algorithms used in vehicles with active suspension systems to adjust vehicle body height include PID control, slicker control, and height closed-loop control. These algorithms all have some drawbacks. For example, while PID control can maintain stability under various conditions, its response to height changes is not linear enough in complex dynamic environments, leading to imprecise adjustments and making parameter tuning difficult. Slicker control, although robust, can cause chattering, affecting comfort. Height closed-loop control, while simple and capable of adjustment in complex nonlinear environments, is often prone to overshoot. The variable-speed height closed-loop control algorithm based on the rate of height change used in active hydraulic suspension not only maintains rapid and stable adjustment in various complex environments but also reduces overshoot.

[0005] In the prior art, patent application number 202310384048.6 discloses a vehicle control method, an active suspension system, a suspension control device, and a vehicle, which discloses that "the active suspension system includes a first suspension structure; the rhythmic action includes an upward movement of the first suspension structure, the upward movement being PID-adjusted by the forward rotation of the motor according to the current vehicle height and a target upward movement height" and "the rhythmic action includes a downward movement of the first suspension structure, the downward movement being PID-adjusted by the reverse rotation of the motor according to the current vehicle height and a target downward movement height".

[0006] In this prior art, when controlling the vehicle, PID adjustment is performed based on height. Although this height closed-loop control strategy aims to maintain the speed of ascent, it still results in a large rotational speed when the target height is reached, leading to overshoot. Overshoot may affect the stability of suspension control and even damage the suspension. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide a closed-loop control method for vehicle suspension with variable speed and height based on the rate of change of height. This method reduces or even eliminates overshoot during the rising phase of suspension control in the rhythmic control process, thereby improving the accuracy and reliability of control.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] The vehicle suspension variable speed height closed-loop control method based on height change rate collects height data and calculates the height change rate in real time during the process of raising the vehicle from the lowest height to the target height through suspension control. The speed of the hydraulic pump is adjusted in real time according to the height change rate to raise the vehicle body to the target height.

[0010] During the process of raising the vehicle body by controlling the suspension, the domain controller sends enable commands and speed commands to the hydraulic pump via CAN signals, and the hydraulic pump starts working according to the speed command corresponding to the command.

[0011] Before raising the vehicle body via the suspension, sensors collect vehicle status information and hydraulic pump status information. Based on the collected vehicle status information and hydraulic pump status information, it is determined whether the current vehicle meets the conditions for raising the vehicle body via the suspension. Only after the conditions are met is it allowed to raise the vehicle body via the suspension.

[0012] The system collects vehicle height data and compares the difference between the height data and the target height with a threshold. When the height difference is greater than the set threshold, the speed of the hydraulic pump is adjusted according to the first desired height change rate. When the difference is less than or equal to the set threshold, the speed of the hydraulic pump is adjusted according to the second desired height change rate.

[0013] When entering the suspension-controlled vehicle height raising process, the initial hydraulic pump speed is first used to control the vehicle height increase, then the vehicle height is collected and the height change rate is calculated, and then the hydraulic pump speed is adjusted based on the height change rate.

[0014] The first expected height change rate is greater than the second expected height change rate. The first expected height change rate is used to control the vehicle height to rise rapidly, while the second expected height change rate is used to control the vehicle height to reach the target height slowly.

[0015] When the height difference exceeds the set threshold, the speed of the hydraulic pump is gradually increased to make the height change rate gradually approach the first desired height change rate. Once the first desired height change rate is reached, the speed of the hydraulic pump is maintained to keep the height change rate constant or near the first desired height change rate.

[0016] When the height difference is less than or equal to the set threshold, the speed of the hydraulic pump is reduced to make the height change rate equal to or close to the second desired height change rate.

[0017] When the height difference is less than or equal to the set threshold, the height data is monitored in real time. When the vehicle height reaches the target height, the suspension control of the vehicle's ascent process ends, and the control hydraulic pump speed drops to 0.

[0018] The advantages of this invention are: when controlling the suspension during the rising phase of rhythmic control, it reduces or even eliminates overshoot, thereby improving the accuracy and reliability of control. Attached Figure Description

[0019] The following is a brief explanation of the contents of each of the accompanying drawings and the markings in the drawings:

[0020] Figure 1 This is a flowchart of the control method of the present invention. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings and the description of the preferred embodiments.

[0022] This embodiment addresses the overshoot issue inherent in existing height-based PID suspension control methods during vehicle ascent. A novel closed-loop control method based on the rate of change of height is designed. This method reduces the ascent speed by adjusting the vehicle speed during ascent, minimizing or eliminating overshoot. This ensures more accurate attainment of the target height without exceeding it, preventing overshoot and subsequent suspension damage. The specific solution is described below:

[0023] The vehicle suspension variable speed height closed-loop control method based on the height change rate only initiates the suspension control vehicle height raising process after the vehicle height raising control conditions are met. By controlling the suspension vehicle height, functions such as vehicle jogging and dancing can be achieved. When the suspension controls the vehicle body to jog or dance, it includes two processes: vehicle rising and vehicle falling. This solution is designed specifically for the vehicle rising process.

[0024] Before raising the vehicle body via suspension control, sensors collect vehicle status information and hydraulic pump status information. Based on the collected vehicle status information and hydraulic pump status information, it is determined whether the current vehicle meets the conditions for suspension control to raise the vehicle body. Only if the conditions are met is raising the vehicle body via suspension control permitted. Then, during the vehicle body raising control process, the speed of the hydraulic pump is adjusted in real time according to the height change rate to raise the vehicle body to the target height. During the process of controlling the vehicle to move rhythmically or dance, it should first determine whether the starting conditions are met. Taking dancing or rhythmic movement as an example, it should be ensured that the hydraulic pump of the suspension system is in normal condition, and the vehicle is at a stationary or near-stationary very low speed. When these conditions are met, it is determined that the starting conditions are met.

[0025] Once the conditions are met, the vehicle begins to rise via suspension control. During this process, as the vehicle rises from its lowest height to the target height, height data is collected in real time, and the rate of height change is calculated. Based on this rate of change, the speed of the hydraulic pump is adjusted in real time to raise the vehicle to the target height. The lowest vehicle height refers to the initial suspension position height set during normal vehicle operation. This is the initial suspension height at which the user initiates vehicle movement or agitation. Controlled by active suspension, specifically by the suspension hydraulic pump, the vehicle height is raised from the initial height to the target height. This process is the vehicle rise process, achieved through hydraulic suspension control. During this suspension-controlled vehicle rise process, the vehicle components involved include the domain controller, which sends enable and speed commands to the hydraulic pump via CAN signals. The hydraulic pump then initiates operation based on the corresponding speed command.

[0026] When control begins, vehicle height data is collected, and the difference between the height data and the target height is compared with a threshold. When the height difference is greater than the set threshold, the speed of the hydraulic pump is adjusted according to the first desired height change rate; when it is less than or equal to the set threshold, the speed of the hydraulic pump is adjusted according to the second desired height change rate.

[0027] The first expected height change rate is greater than the second expected height change rate. The first expected height change rate is used to control the vehicle height to rise rapidly, while the second expected height change rate is used to control the vehicle height to reach the target height slowly.

[0028] During the process of rising from the initial height to the target height, the initial height is the starting height. At this point, an initial hydraulic pump speed is allocated to control the vehicle's height increase. Because the initial speed is low, the resulting rate of height change is small. To quickly reach the target height, the speed is increased to improve the rate of height change, achieving a desired level. When the suspension controls the vehicle's height increase, the initial hydraulic pump speed is first used to control the vehicle's height rise. Then, the vehicle height is collected and the rate of height change is calculated. The hydraulic pump speed is then adjusted based on this rate of change. A first desired rate of height change is set; this rate of change allows the vehicle to rise rapidly, approaching the target height. The height difference is used for judgment.

[0029] When the height difference exceeds a set threshold, it indicates a significant distance from the target high speed. The hydraulic pump speed is gradually increased to bring the height change rate closer to the first desired height change rate. Once the first desired height change rate is reached, the hydraulic pump speed is maintained to keep the height change rate constant or near it. When the distance to the target high speed is still considerable, the hydraulic pump speed is increased to bring the height change rate closer to or equal to the first desired high speed change rate, causing the vehicle body to rise rapidly. After rising to a certain level, when the height difference is less than or equal to the set threshold, the hydraulic pump speed is decreased to bring the height change rate equal to or close to the second desired height change rate. The second desired height change rate is a smaller vehicle body change rate, allowing for a slow approach to or attainment of the target height, thus avoiding overshoot caused by excessively high speed.

[0030] When the height difference is less than or equal to a set threshold, the height data is monitored in real time. When the vehicle height reaches the target height, the suspension control of the vehicle's ascent process ends, and the control hydraulic pump speed drops to 0. When using a second desired height change rate to control the vehicle's continued ascent, once the height equals the target height, the ascent process ends, the control hydraulic pump speed drops to 0, and the ascent control ends. At this point, traditional height PID control can be used to drive the suspension to lower the vehicle height, thus achieving vehicle rhythmic or dancing control. By controlling the ascent process using the above scheme, overshoot is reduced or even avoided, improving the accuracy and reliability of control during the ascent process.

[0031] The following explanation uses the "dancing" function of vehicle suspension control as an example. "Dancing" refers to controlling the suspension to move up and down rhythmically, similar to dancing. The solution includes: issuing a "dancing" command signal via the HMI touchscreen; collecting vehicle status information and the status information of actuators such as hydraulic pumps through sensors; and determining whether the conditions for "dancing" are met based on the current vehicle status. When the conditions are met, the domain controller sends an enable command and a speed command to the hydraulic pump via CAN signal, initiating the pump's operation. The hydraulic pump then feeds back its actual speed and status information to the domain controller. Simultaneously, the sensor collects the current vehicle height to determine the appropriate pump speed for the next moment, thus raising and lowering the vehicle body.

[0032] In this embodiment, the "dancing" function of the active hydraulic suspension employs a closed-loop control strategy based on the rate of change of height. To enable the vehicle body to rise quickly and smoothly, the speed of the hydraulic pump is adjusted to maintain a relatively high rate of ascent. During the ascent, this control strategy has three phases: The first phase is the acceleration phase, where the rate of change of height is low. A higher speed is issued to the hydraulic pump to allow the vehicle body to reach the desired rate of change of height quickly. The second phase is the smooth ascent phase, where the rate of change of height is at the desired level. The speed is adjusted to maintain the rate of change of height near the desired value, resulting in a smooth ascent of the vehicle body. The third phase is the deceleration phase, occurring just before reaching the target height. To prevent overshoot, the speed is reduced to decrease the rate of change of height, ensuring the vehicle body reaches the target height without overshoot.

[0033] In this design, the "dancing" function of the active hydraulic suspension employs a variable speed height closed-loop control strategy based on the rate of height change. This achieves the goal of ascending at a high speed while minimizing overshoot and maintaining the target position.

[0034] The "dancing" function of the active hydraulic suspension employs a highly closed-loop control strategy. The command signal for the dancing function is sent via the HMI touchscreen. Sensors then collect vehicle status information and the status information of actuators such as the hydraulic pump. The active hydraulic suspension control system determines whether the conditions for dancing are met based on the current vehicle status. When the conditions are met, the domain controller sends enable and speed commands to the hydraulic pump via CAN signals, initiating pump operation. The hydraulic pump then feeds back its actual speed and status information to the domain controller. Simultaneously, sensors collect the current actual height and the calculated rate of change of height to determine the next speed of the hydraulic pump, thus raising and lowering the vehicle body.

[0035] While the above closed-loop height control strategy aims to maintain the ascent speed, it can still result in a relatively high rotational speed upon reaching the target height, leading to overshoot. The "dancing" function of the active hydraulic suspension employs a variable-speed height closed-loop control strategy based on the rate of height change. To ensure rapid and smooth ascent, the rotational speed of the hydraulic pump is varied to maintain a relatively high ascent speed. During ascent, this control strategy has three phases: the first phase is the acceleration phase, where the rate of height change is low, and a higher rotational speed is sent to the hydraulic pump to allow the vehicle to reach the desired rate of height change quickly. The second phase is the smooth ascent phase, where the rate of height change is at the desired level. By adjusting the rotational speed, the height conversion rate is maintained near the desired value, resulting in a smooth ascent. The third phase is the deceleration phase, occurring just before reaching the target height. To prevent overshoot, the rotational speed is reduced to decrease the rate of height change, ensuring the vehicle reaches the target height without overshoot.

[0036] All control algorithms based on the rate of change of height and variable speed height closed loop mentioned in this invention are within the scope of protection of this patent.

[0037] Obviously, the specific implementation of this invention is not limited to the above-described methods. Any non-substantial improvements made using the inventive concept and technical solution of this invention are within the protection scope of this invention.

Claims

1. A closed-loop control method for vehicle suspension with variable speed and height based on the rate of change of height, characterized in that: During the process of raising the vehicle by controlling the suspension, as the vehicle moves from its lowest height to the target height, height data is collected in real time and the rate of height change is calculated. Based on the rate of height change, the speed of the hydraulic pump is adjusted in real time to raise the vehicle body to the target height. The system collects vehicle height data and compares the difference between the height data and the target height with a threshold. When the height difference is greater than the set threshold, the speed of the hydraulic pump is adjusted according to the first desired height change rate. When the difference is less than or equal to the set threshold, the speed of the hydraulic pump is adjusted according to the second desired height change rate. When entering the suspension control vehicle height raising process, the initial hydraulic pump speed is first used to control the vehicle height increase, then the vehicle height is collected and the height change rate is calculated, and then the hydraulic pump speed is adjusted based on the height change rate. The first expected height change rate is greater than the second expected height change rate, where the first expected height change rate is used to control the vehicle height to rise rapidly; the second expected height change rate is used to control the vehicle height to reach the target height slowly. When the height difference exceeds the set threshold, the speed of the hydraulic pump is gradually increased to make the height change rate gradually approach the first desired height change rate. Once the first desired height change rate is reached, the speed of the hydraulic pump is maintained to keep the height change rate constant or near the first desired height change rate.

2. The vehicle suspension variable speed height closed-loop control method based on height change rate as described in claim 1, characterized in that: During the process of raising the vehicle body by controlling the suspension, the domain controller sends enable commands and speed commands to the hydraulic pump via CAN signals, and the hydraulic pump starts working according to the speed command corresponding to the command.

3. The vehicle suspension variable speed height closed-loop control method based on height change rate as described in claim 2, characterized in that: Before raising the vehicle body via the suspension, sensors collect vehicle status information and hydraulic pump status information. Based on the collected vehicle status information and hydraulic pump status information, it is determined whether the current vehicle meets the conditions for raising the vehicle body via the suspension. Only after the conditions are met is it allowed to raise the vehicle body via the suspension.

4. The vehicle suspension variable speed height closed-loop control method based on height change rate as described in claim 1, characterized in that: When the height difference is less than or equal to the set threshold, the speed of the hydraulic pump is reduced to make the height change rate equal to or close to the second desired height change rate.

5. The vehicle suspension variable speed height closed-loop control method based on height change rate as described in claim 1, characterized in that: When the height difference is less than or equal to the set threshold, the height data is monitored in real time. When the vehicle height reaches the target height, the suspension control of the vehicle's ascent process ends, and the control hydraulic pump speed drops to 0.

Images