A method and apparatus for controlling a seat damper using road surface conditions.

Abstract

The Skyhook control method is improved to enhance the ride comfort of the vehicle, even without additional sensors. [Solution] The present invention relates to a skyhook control method for seat damper control, which estimates the wheel vertical acceleration using the measurement value of a wheel speed sensor, estimates the road surface condition based on the estimated wheel vertical acceleration, and controls the seat damper by changing the skyhook control method based on this, thereby improving the skyhook control method and improving the ride comfort of the vehicle without the need for any additional sensors.

Description

Technical Field

[0001] The present invention relates to damper control of a vehicle, and particularly to semi-active control technology of a seat damper.

Background Art

[0002] In order to improve the riding comfort of a passenger car, a method of controlling dampers connected to each wheel is generally used.

[0003] However, unlike a passenger car, in the case of a large truck, improving the riding comfort of the driver's seat is limited only by controlling the suspension and damper of each wheel. Therefore, in order to improve the riding comfort of the driver's seat of a truck, an attempt has been made to install another damper in the driver's seat and control it to improve the riding comfort of the truck.

[0004] The Skyhook control method is widely used to improve the riding comfort of a truck using a driver's seat damper. The Skyhook control method was proposed by Karnopp and is a control method that detects vehicle vibrations by frequency and attempts to reduce the vertical acceleration of the vehicle body or seat.

[0005] The Skyhook control method basically sets a virtual fixed point above the vehicle body, provides a damper between the fixed point and the vibration surface, and aims to reduce the vibration of the vehicle body according to the road surface condition. However, in reality, since it is impossible to set a virtual fixed point, a method is used in which a variable damper is provided between the vehicle body and the wheel to create the damping force that a virtual damper between the virtual fixed point and the vehicle body should create instead. Such a Skyhook control method is used in an active or semi-active suspension system.

[0006] When such a semi-active seat damper is installed in a truck and Skyhook control is performed, there is a large difference in control performance depending on the driving conditions.

[0007] Figure 7 shows the test results of this conventional skyhook control method under different road surface conditions.

[0008] Even when using the same skyhook control logic, the frequency response in the driver's seat changes depending on the driving conditions (#gravel, #40kJ bump, #80kJ bump, #90kph driving), confirming that the skyhook control performance differs.

[0009] Ultimately, the conventional skyhook control method, which does not take road surface conditions into account as a driving condition, has the problem of potentially worsening ride comfort.

[0010] To address these issues by using a method that takes road surface conditions into account, it would be necessary to install additional sensors to measure the vertical acceleration of the seat, which introduces another disadvantage: increased cost.

[0011] The inventors of this invention have made research efforts to improve upon the problems of these prior art skyhook control methods. After much effort to provide a seat damper control method and apparatus that can improve the skyhook control method by estimating road surface conditions without additional sensors, the inventors have completed this invention. [Overview of the initiative] [Problems that the invention aims to solve]

[0012] The object of the present invention is to provide a seat damper control method and apparatus that can improve the skyhook control method by further considering road surface conditions.

[0013] Another object of the present invention is to provide a method for accurately estimating road surface conditions without the need for additional sensors to estimate road surface conditions.

[0014] On the other hand, other purposes of the present invention that are not explicitly stated will be further considered to the extent that they can be easily inferred from the following detailed description and its effects. [Means for solving the problem]

[0015] A damper control method according to one embodiment of the present invention for solving the aforementioned problems may include the steps of: estimating road surface conditions; changing the skyhook control method according to the estimated road surface conditions; and controlling the damper by the changed skyhook control method.

[0016] In one embodiment of the present invention, the step of estimating the road surface condition may be performed based on the wheel speed measured by a wheel speed sensor.

[0017] In one embodiment of the present invention, the wheel speed may be filtered by a high-pass filter and used to estimate the road surface condition.

[0018] In one embodiment of the present invention, the estimated road surface condition may include the roughness of the road surface and the presence or absence of obstacles on the road surface.

[0019] In one embodiment of the present invention, the step of changing the skyhook control method may include changing the skyhook control method based on the roughness of the road surface and the presence or absence of obstacles on the road surface, among the estimated road surface conditions.

[0020] In one embodiment of the present invention, the damper may be a seat damper.

[0021] A damper control device according to an embodiment of the present invention for solving the above problems includes a communication unit for receiving a sensor signal from an external sensor, and a control unit including one or more processors and a memory. The control unit estimates the road surface condition using the sensor signal received via the communication unit, changes the skyhook control method according to the estimated road surface condition, and can control the damper by the changed skyhook control method.

[0022] In one embodiment of the present invention, the external sensor is a wheel speed sensor, and the control unit can estimate the road surface condition by the wheel speed measured by the wheel speed sensor.

[0023] In one embodiment of the present invention, the wheel speed can be filtered by a high-pass filter and used for estimating the road surface condition.

[0024] In one embodiment of the present invention, the estimated road surface condition may include the roughness of the road surface and the presence or absence of road surface obstacles.

[0025] In one embodiment of the present invention, the control unit can classify the skyhook control method according to the roughness of the road surface and the presence or absence of road surface obstacles among the estimated road surface conditions and change the skyhook control method.

[0026] In one embodiment of the present invention, the damper may be a seat damper.

Advantages of the Invention

[0027] According to the present invention, it is possible to accurately estimate the road surface condition without an additional sensor, and by further subdividing the skyhook control according to the estimated road surface condition, there is an effect of improving the riding comfort.

[0028] Also, since no additional sensor is used, there is an advantage that the riding comfort can be improved without adding cost.

[0029] On the other hand, even effects not explicitly mentioned herein, as well as the effects described below in the specification and their provisional effects that are expected by the technical features of the present invention, shall be treated as described in the specification of the present invention. [Brief explanation of the drawing]

[0030] [Figure 1] Figure 1 is a schematic flowchart of a damper control method according to a preferred embodiment of the invention. [Figure 2] Figure 2 is a schematic flowchart of a skyhook control method according to a preferred embodiment of the present invention. [Figure 3] Figure 3 is a schematic diagram of the overall system in which a damper control device according to another preferred embodiment of the present invention is used. [Figure 4] Figure 4 is a schematic diagram of a damper control device according to another preferred embodiment of the present invention. [Figure 5] Figure 5 is a comparison chart of vertical acceleration measured by a vertical acceleration sensor and wheel speed measured and processed by a wheel sensor. [Figure 6] Figure 6 is a graph showing the performance of the damper control method and apparatus according to the present invention. [Figure 7] Figure 7 is a graph showing the performance of a conventional skyhook control method. [Modes for carrying out the invention]

[0031] The aforementioned objectives, means, and effects of the present invention will become clearer from the following detailed description in relation to the accompanying drawings, so that a person with ordinary skill in the art to which the present invention pertains can easily implement the technical idea of ​​the present invention. Furthermore, in describing the present invention, if it is determined that a specific description of prior art according to the present invention would unnecessarily obscure the gist of the present invention, such detailed description will be omitted. It should be made clear that the accompanying drawings are provided as illustrative examples for understanding the technical idea of ​​the present invention, and this does not limit the scope of the rights of the present invention.

[0032] The terms used herein are for illustrative purposes only and do not limit the invention. In this specification, the singular form may include the plural form unless otherwise specified in the context. In this specification, terms such as “includes,” “equip,” “provide,” or “have” do not preclude the existence or addition of one or more other components other than those mentioned.

[0033] In this specification, terms such as “or” and “at least one” may refer to one of the words listed together or to a combination of two or more words. For example, “A or B” and “at least one of A and B” may include only one of A or B, or both A and B.

[0034] In this specification, descriptions such as “for example” should not limit the embodiments of the invention by any effect such as variations, including tolerances, measurement errors, limits of measurement accuracy, and other commonly known factors, as the information presented may not be exactly the same as the cited characteristics, variables, or values.

[0035] In this specification, when a component is described as being "linked" or "connected" to another component, it should be understood that it is directly linked to or may be connected to the other component, but that other components may exist in between. On the other hand, when a component is described as being "directly linked" or "directly connected" to another component, it should be understood that there are no other components in between.

[0036] In this specification, when a component is described as being "on top of" or "in contact with" another component, it should be understood that it may be in direct contact with or connected to the other component, but there may also be other components in between. On the other hand, when a component is described as being "directly on top of" or "in direct contact with" another component, it should be understood that there are no other components in between. Other expressions describing the relationship between components, such as "between" and "directly between," can be interpreted in the same way.

[0037] In this specification, terms such as "first," "second," etc., may be used to describe various components, but the components should not be limited by such terms. Furthermore, such terms should not be interpreted as limiting the order of the components, but rather as being used to distinguish one component from another. For example, "first component" may be named "second component," and similarly, "second component" may be named "first component."

[0038] Unless otherwise defined, all terms used herein should be used in a way that is commonly understood by those skilled in the art to which the invention pertains. Furthermore, terms defined in commonly used dictionaries should not be interpreted ideally or excessively unless specifically defined otherwise.

[0039] A preferred embodiment of the present invention will be described in detail below with reference to the attached drawings.

[0040] Figure 1 is a schematic flowchart of a damper control method according to a preferred embodiment of the present invention.

[0041] The damper control method of the present invention may be performed by a control unit including one or more processors and memory.

[0042] First, the wheel speed is measured in S110 for damper control, and based on this, the road surface condition is estimated in S120.

[0043] Generally, road surface conditions are estimated by measuring and utilizing the vertical acceleration of the vehicle's body or wheels. However, measuring vertical acceleration requires a separate acceleration sensor (G sensor), which inevitably leads to an increase in price.

[0044] Therefore, in this invention, the road surface condition is estimated using existing sensors without the need for additional sensors, and based on this, semi-active control of the seat damper is performed.

[0045] Wheel speed measurement is performed by a wheel speed sensor, and the measured wheel speed value can be received via a vehicle communication network such as CAN communication. The wheel speed sensor can be the same one used in driver assistance systems such as ADAS (Advanced Driving Assistance System) or vehicle control systems such as ABS / TCS.

[0046] Wheel speed values ​​can be processed using a high-pass filter (HPF). The wheel speed values ​​processed by the high-pass filter can exhibit a similar trend to the vertical acceleration values ​​of the wheel or the vehicle body.

[0047] Figure 5 is a comparison diagram of the vertical acceleration measured by the vertical acceleration sensor and the wheel speed measured and processed by the wheel speed sensor.

[0048] The graph of the wheel speed value measured by the wheel speed sensor (Whl Spd Sensor) after signal processing (high-pass filtering) and the value measured by the wheel vertical acceleration sensor (Whl Vertical G Sensor) show similar waveforms.

[0049] Figure 5(a) shows the wheel speed and wheel vertical acceleration values ​​when driving on a cement-paved road, and Figure 5(b) shows the wheel speed and wheel vertical acceleration values ​​when passing over an obstacle (bump).

[0050] Therefore, estimating the road surface condition using the wheel speed values ​​measured by a wheel speed sensor and filtered using a high-pass filter has a similar effect to estimating the road surface condition using the vertical acceleration values ​​measured by a vertical acceleration sensor.

[0051] Road surface conditions can be broadly categorized by their roughness and the presence or absence of obstacles.

[0052] The roughness of the road surface distinguishes between paved and unpaved roads, and the type of pavement (asphalt, cement, concrete), while the presence or absence of obstacles refers to temporary irregularities in the road surface such as steps or stones.

[0053] The roughness of the road surface and the presence or absence of obstacles are determined by an algorithm that compares pre-stored waveforms with the actual road surface conditions.

[0054] After estimating and specifically classifying the road surface conditions in this way, the S130 performs skyhook control accordingly.

[0055] In this invention, by broadly classifying the road surface conditions according to their roughness and the presence or absence of obstacles, skyhook control can be further subdivided.

[0056] Skyhook control may be applied to dampers on the seats, or to dampers connected to the wheels of the vehicle body, but is not limited to these.

[0057] Figure 2 is a schematic flowchart of a skyhook control method according to a preferred embodiment of the present invention.

[0058] First, it is determined in S132 whether the road surface conditions meet the requirements for skyhook control. If the control conditions are not met, damping force is not applied to the damper in S133. In other words, skyhook control is not performed unless the road surface conditions require it.

[0059] The conditions under which skyhook control is necessary can be interpreted as situations where controlling the skyhook effectively provides vibration damping. Conversely, if controlling the skyhook would actually hinder damping and increase the amplitude, then the skyhook should not be controlled. Whether or not skyhook control is necessary can be changed in real time.

[0060] If the road surface conditions are deemed to require skyhook control, the skyhook control will be subdivided depending on the presence or absence of obstacles. For this purpose, S134 first determines the presence or absence of obstacles.

[0061] The presence or absence of obstacles can be determined by applying a high-pass filter to the wheel speed sensor values ​​and then applying it to a pre-stored discrimination algorithm.

[0062] Obstacle detection can be performed by a separately provided obstacle detection sensor (not shown).

[0063] If no obstacle is detected, S136 performs road surface proportional skyhook control only based on the road surface roughness.

[0064] In other words, the surface roughness of the road surface without obstacles is estimated using wheel speed sensor values, and the damper's damping force is adjusted using skyhook control based on the estimated roughness.

[0065] If an obstacle is detected, S135 performs proportional skyhook control according to the obstacle.

[0066] In other words, since the impact on the vehicle or seat changes depending on the size of the obstacle, the damper's damping force is adjusted by performing skyhook control in proportion to this. If skyhook control is performed solely based on the roughness of the road surface, the ride comfort may worsen when there is an obstacle. Therefore, in this invention, the skyhook control method is different to take into account the case when there is an obstacle.

[0067] Figure 3 is a schematic diagram of the overall system in which a damper control device according to another preferred embodiment of the present invention is used.

[0068] The damper control device 100 according to the present invention includes a sensor unit 130, which will be described later, and acquires the acceleration of the sprung mass and unsprung mass respectively to grasp the skyhook control conditions of the damper 1 itself. It is connected to an internal vehicle communication network such as CAN, and through this, it receives sensor values ​​from a wheel speed sensor 200 to estimate the road surface conditions, and controls the damper 1 by adjusting the skyhook control conditions according to the estimated road surface conditions.

[0069] The damper 1 control performs skyhook control based on the acceleration of the sprung mass and unsprung mass acquired by the acceleration sensor. The road surface condition is estimated using the wheel speed value received from the wheel speed sensor 200, and the skyhook control method is adjusted based on this to control the damper 1.

[0070] Figure 4 is a schematic diagram of a damper control device according to another preferred embodiment of the present invention.

[0071] The damper control device 100 according to the present invention may include a sensor unit 130, a communication unit 120, and a control unit 110.

[0072] The sensor unit 130 may include a plurality of acceleration sensors for measuring the acceleration of the sprung mass and unsprung mass, respectively. The control unit 110 estimates the respective velocities and relative velocities from the accelerations of the sprung mass and unsprung mass detected by the sensor unit 130, respectively, and performs proportional control of the damper 1.

[0073] However, the control unit 110 can estimate the road surface condition from the wheel speed detected by the wheel speed sensor 200 and apply a different specific proportional control algorithm to the damper 1 based on the road surface condition.

[0074] The communication unit 120 can be used to connect the damper control device 100 to an in-vehicle network such as CAN or an external LTE / 5G network.

[0075] The control unit 110 may include one or more processors 112 and memory 114.

[0076] Memory 114 stores various information necessary for the operation of the damper control device 100. The information stored in the memory may include, but is not limited to, various sensor values ​​received from the sensors, information for the control operation of the control unit 110, information that is signal-processed or analyzed by the control unit 110, and program information regarding the control method.

[0077] For example, memory 114 may include, but is not limited to, hard disk type, magnetic media type, CD-ROM (Compact Disc Read Only Memory), optical media type, magneto-optical media type, multimedia card micro type, flash memory type, ROM type (Read Only Memory Type), or RAM type (Random Access Memory Type), depending on its type. Also, memory 114 may be a cache, buffer, main memory, or auxiliary memory, or a separately provided storage system, depending on its use / location, but is not limited to these.

[0078] The control unit 110 can perform various control operations of the damper control device 100. Specifically, the control unit 110 can control signal processing and analysis of the wheel speed value received from the wheel speed sensor 200, and can perform damper control methods recorded in the memory 114. For example, the control unit 110 may include, but is not limited to, a hardware processor 112, or a software process executed on the processor.

[0079] The control unit 110 can receive wheel speed sensor values ​​via the communication unit 120 and estimate the road surface conditions. The wheel speed sensor 200 can be the same wheel speed sensor used in driver assistance systems such as ADAS (Advanced Driving Assistance System) or vehicle control systems such as ABS / TCS.

[0080] When wheel speed values ​​are passed through a high-pass filter, they have a value similar to the wheel or vehicle body vertical acceleration value, which can then be used to estimate the road surface condition.

[0081] Road surface conditions can be broadly categorized into two main types: surface roughness and the presence or absence of obstacles.

[0082] By broadly classifying road surface conditions according to roughness and the presence or absence of obstacles, skyhook control can be further refined.

[0083] Skyhook control may be applied to the seat dampers, or to dampers connected to the vehicle's wheels, but is not limited to these.

[0084] First, the system determines whether the road surface conditions necessitate skyhook control. If the conditions are not met, skyhook control is not performed.

[0085] If the road surface conditions are deemed to require skyhook control, the skyhook control will be subdivided depending on the presence or absence of obstacles.

[0086] First, the system determines whether or not there are obstacles. If no obstacles are detected, it performs road surface proportional skyhook control based solely on the road surface roughness. The detailed determination method is as described above.

[0087] If an obstacle is detected, proportional control is performed according to the type of obstacle, and skyhook control, i.e., the damping force of the damper, is adjusted according to the type of obstacle.

[0088] Thus, the damper control method and apparatus of the present invention have the effect of improving the situation-dependent skyhook control method without adding sensors for measuring the vertical acceleration of the seat or vehicle body.

[0089] Figure 6 is a graph showing the performance of the damper control method and apparatus according to the present invention.

[0090] Compared to conventional skyhook damper control with soft damper damping force (Conv(Soft), square) and conventional skyhook damper control with strong damper damping force (Conv(Hard), triangular), it can be confirmed that vertical vibrations with the semi-active damper control (SDC(Control), circular) according to the present invention are reduced across the entire frequency range.

[0091] While specific embodiments have been described in the detailed description of the present invention, it goes without saying that various modifications are possible as long as they do not deviate from the scope of the invention. Therefore, the scope of the present invention is not limited to the embodiments described, but must be defined by the claims described below and any equivalents thereof.

Claims

1. A damper control method performed by a control unit including one or more processors and memory, Steps to estimate road surface conditions, The steps include changing the skyhook control method according to the estimated road surface conditions, A damper control method characterized by comprising the step of controlling a damper by the modified skyhook control method.

2. The step of estimating the road surface condition is: The damper control method according to claim 1, characterized in that the road surface condition is estimated based on the wheel speed measured by a wheel speed sensor.

3. The aforementioned wheel speed is, The damper control method according to claim 2, which is filtered by a high-pass filter and used for estimating the road surface condition.

4. The estimated road surface conditions are, A damper control method according to claim 1, including the roughness of the road surface and the presence or absence of obstacles on the road surface.

5. The step of changing the skyhook control method is: The damper control method according to claim 1, further comprising the step of changing the skyhook control method based on the roughness of the road surface and the presence or absence of obstacles on the road surface among the estimated road surface conditions.

6. The damper control method according to claim 1, wherein the damper is a seat damper.

7. A communication unit for receiving sensor signals from an external sensor, A control unit including one or more processors and memory, The control unit, The road surface condition is estimated using the sensor signals received via the aforementioned communication unit. The skyhook control method is changed according to the estimated road surface conditions. A damper control device that controls a damper by the modified skyhook control method described above.

8. The aforementioned external sensor is a wheel speed sensor, The control unit, The damper control device according to claim 7, characterized in that it estimates the road surface condition based on the wheel speed measured by the wheel speed sensor.

9. The aforementioned wheel speed is, The damper control device according to claim 8, which is filtered by a high-pass filter and used for estimating the road surface condition.

10. The estimated road surface conditions are, The damper control device according to claim 7, including the roughness of the road surface and the presence or absence of obstacles on the road surface.

11. The damper control device according to claim 7, wherein the control unit classifies the skyhook control method based on the roughness of the road surface and the presence or absence of obstacles on the road surface from the estimated road surface conditions and changes the skyhook control method.

12. The damper control device according to claim 7, wherein the damper is a seat damper.

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