Vertical load controlled Anti-SKID management system

Abstract

The invention relates to a vertical load controlled anti-skid management system that continuously or intermittently increases, decreases or keeps the downforce of the wheels constant on the road by changing the damping level of the shock absorber with variable damping according to the change in brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles, and thus prevents the wheels from skidding or reduces the skidding.

Description

[0001] Vertical Load Controlled Anti-Skid Management System

[0002] TECHNICAL FIELD

[0003] The invention relates to a vertical load controlled anti-skid management system that increases, decreases or keeps the wheels' downforce constant by changing the damping level of the shock absorber with variable damping according to the change in brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles, and thus prevents the wheels from skidding or reduces the skidding speed.

[0004] PRIOR ART

[0005] The anti-skid control system used in today's vehicles, when a wheel is detected to be skidding, observes the acceleration-slip change and intervenes in the brake system and engine management system to slow down the wheels or prevent them from skidding or to get rid of the skid. While the brake torque is changed via the brake pressure in the brake system, the wheel is slowed down by changing the engine torque via the throttle valve opening in the engine management system. Thus, the skidding wheel can be controlled. When the rotational speed of the wheel is low during skidding, the skid control system increases the brake pressure to prevent skidding. At high rotational speeds, it slows down the engine rotational speed and the wheel by reducing the throttle opening independently of the driver or by delaying the ignition. In this way, in today's anti-skid control systems, the skidding wheel is tried to be controlled either by braking, by reducing the rotational torque, or by combining both interventions.

[0006] The general working principle of the current anti-skid control system is as follows:

[0007] The control curves of the anti-skid control system are shown in Figure 1. Curves numbered 1, 2, 3 and 4 given in Figure 1 show the wheel speed changes, the amount of fuel sprayed, the brake pressure change and the opening and closing movements of the inlet-outlet solenoid valve, respectively. Anti-skid control systems first increase the brake pressure when the linear speed of the wheel is below 30 km / h when the wheel first falls into skid. With this increase, the wheel is momentarily slowed down. After this moment, the brake pressure is gradually reduced, increasing the effect of the friction force of the wheel, and in this way, the wheel is allowed to move forward without skidding. It is a known fact that the anti-skid control systems used in today's vehicles have difficulties in controlling skidding on slippery surfaces. Since the solution to this problem is possible by developing methods that can improve the grip of the tire on the road during skidding, it is thought that similar methods that can be developed by third parties will inevitably conflict with the wheel load integrated anti-skid control system that is the subject of the invention. Within the scope of the literature review regarding the anti-skid control system that is the subject of the invention, publication and patent researches have been conducted and control methods such as PID and sliding mode control have been applied in the relevant systems and no studies on integration have been encountered. At the same time, many brands and models that have been introduced for the first time today have been examined and no integrated system has been encountered other than the traditional anti-skid control system.

[0008] There are some problems with the currently used skid control systems. The most important of these are as follows:

[0009] • The friction potential is obtained late or not obtained at all during skid control, which causes the wheel to skid for a long time or prevents the wheel from skidding. This situation becomes more evident especially on icy ground and slippery rough terrain where friction is difficult to be obtained. In such conditions, precautions must be taken to facilitate the emergence of friction in order to be able to control skid. In order to achieve this, applications that can increase the friction torque between the tire and the road and thus enable the braking torque to be used at a higher level are required.

[0010] • Other problem is that the wheel power and torque are not enough to move the vehicle due to the reduced throttle valve opening during skid control with engine torque.

[0011] • The other problem is that the engine management system needs to reduce the engine torque below the torque that can move the vehicle in order to prevent skidding. These situations cause the vehicle to remain stationary on the road without moving, especially on snowy, icy, muddy roads with upward slopes, even if the wheel has recovered from skidding. In addition, this situation becomes more serious due to the higher torque drop during skidding, where there is very little grip. At this time, in order for the vehicle to move, it is necessary to transfer enough power and torque to the wheels to overcome the vehicle resistances. For this, the intervention of the engine management system should be reduced and the engine torque should be increased again by increasing the throttle valve opening. This situation can only be achieved today by disabling the skid control system.

[0012] • Another problem is that when controlling the skid with brake pressure and providing directional control during skidding, the extension of the brake system's activation time causes the brake system to overload and this causes brake system failures. It is a known fact that brake pads wear out very quickly with the skid control system. In addition, since variable torque cannot be transferred to each wheel, in the event of the vehicle sliding to the right or left during skidding, the vehicle's direction control and engine torque intervention cannot be performed.

[0013] Considering the above problems, the anti-skid control system is needed that can intervene in the skid with engine torque management while ensuring that the engine torque remains at a level that will facilitate the movement of the vehicle and also reduce the brake load. Since the performance of anti-skid systems depends on the grip between the tire and the road, an antiskid control system that can control the grip through the wheel load and control the wheel load during skid control is needed.

[0014] As a result of the research conducted in the literature, a Turkish patent application with the application number "2021 / 014882" and the invention title " SYNCHRONIZED REDUCED ANTI-SKID AND TORQUE DISTRIBUTION DIFFERENTIAL SYSTEM" was found. The application in question is related to a system that carries out the motion difference transfers (increasing or decreasing) in proportion to the reaction forces coming to the right and left motion output groups with a 1 / 1 ratio transmitted from the center differential body to the left and right motion output groups via the main shaft, by transmitting them to the center differential via the right and left transmission groups and transmitting them to the transmission group of the opposite motion output group, taking into account that the total of the motion inputs and motion outputs of a differential system is 3, and that each motion input can be used as a motion output and each motion output can be used as a motion input, 2 motion inputs can be used as 1 motion output, 1 motion input can be used as 2 motion outputs, according to the need in the design. The application in question is related to a system that carries out the motion difference transfers (increasing or decreasing) in proportion to the reaction forces coming to the right and left motion output groups with a 1 / 1 ratio transmitted from the center differential body to the left and right motion output groups via the main shaft, by transmitting them to the center differential via the right and left transmission groups and transmitting them to the transmission group of the opposite motion output group, taking into account that the total of the motion inputs and motion outputs of a differential system is 3, and that each motion input can be used as a motion output and each motion output can be used as a motion input, 2 motion inputs can be used as 1 motion output, 1 motion input can be used as 2 motion outputs, according to the need in the design. However, in the application mentioned, there is no indication of a vertical load controlled antiskid management system that increases, decreases or keeps the wheels' downforce constant by changing the damping level of the shock absorber with variable damping according to the change in brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles, and thus prevents the wheels from skidding or reduces the skidding speed.

[0015] As a result, the problems mentioned above, which cannot be solved in the light of existing technology, have made it mandatory to realize innovation in the relevant technical field.

[0016] BRIEF DESCRIPTION OF THE INVENTION

[0017] The present invention relates to a vertical load controlled anti-skid management system to eliminate the above-mentioned disadvantages and bring new advantages to the relevant technical field.

[0018] The main purpose of the invention is to increase, decrease or keep the downforce of the wheels on the road constantly or intermittently by changing the damping level of the shock absorber with variable damping according to the change in brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles, and thus to prevent the wheels from skidding or to reduce the skidding speed.

[0019] Another purpose of the invention is to intervene in the skidding by engine torque management, to ensure that the engine torque remains at a level that facilitates the movement of the vehicle and to reduce the brake load.

[0020] In order to realize all the purposes mentioned above and to be revealed from the detailed explanation below, the present invention is a vertical load controlled anti-skid management system that increases, decreases or keeps the force of the wheels on the road constantly or intermittently by changing the damping level according to the change in the brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles and thus prevents the wheels from skidding or reduces the skidding speed, and its feature is; at least one wheel speed sensor that allows the linear speed of the wheel on the vehicle to be measured, variable damping shock absorber that allows the appropriate wheel load to be obtained by changing the damping level in order to increase the working distance of the wheel and to ensure that the wheel operates with less load, variable damping shock absorber that adjusts the load of the wheels that are not driven or not in skidding to bring it to the ride height of the vehicle body in order to change the load on the skidding wheel when one or more of the vehicle's wheels are subject to skidding, height potentiometer that measures the movement direction of the variable damping shock absorber and allows the ride height to be determined, damper trigger cable that allows the damper current to be changed to change the damping level of the variable damping shock absorber, brake pressure sensor that measures the applied brake pressure to transmit to the control unit, hydraulic modulator that increases, decreases or keeps the brake pressure constant according to the commands coming from the control unit, wheel acceleration calculation and decision-making algorithm that calculates the wheel acceleration with the data it receives from the wheel speed sensor through the software run inside it and determines whether the wheel slows down or accelerates according to the speed change of the wheel, shock absorber movement direction determination algorithm that determines the direction of the wheel load change, the compression or expansion of the wheel according to the load effect matrix through the software run inside it to transmit to the control unit, vehicle speed and slip rate calculation unit that determines the slip rate according to the wheel speed and vehicle speed through the software run inside it, throttle potentiometer that reduces the wheel torque by decreasing the throttle valve opening or increases the wheel torque by increasing the throttle valve opening according to the commands coming from the control unit, It contains the control unit mentioned above, which communicates with wheel speed sensor, the variable damping shock absorber, height potentiometer, damper trigger cable, brake pressure sensor, hydraulic modulator, wheel acceleration calculation and decision-making algorithm, shock absorber movement direction determination algorithm, vehicle speed and slip rate calculation unit and throttle potentiometer, compares instantly according to the load effect matrix using the wheel acceleration, variable damping shock absorber movement direction, slip rate and brake pressure and determines the damping level, and sends commands to the variable damping shock absorber, damper trigger cable, hydraulic modulator and throttle potentiometer according to the determined damping level.

[0021] In order to best understand the structure of the present invention and its advantages together with the additional elements, it should be evaluated together with the figures explained below.

[0022] BRIEF DESCRIPTION OF THE FIGURES

[0023] Figure 1 is a representative representation of the anti-skid control system function curves. Figure 2 is a representative representation of the wheel model to which the brake and drive torque are applied.

[0024] Figure 3 is a representative representation of the change of the adhesion coefficient according to the slip on different roads.

[0025] Figure 4 is a representative representation of the change of the friction force depending on the acceleration slip. Figure 5 is a representative representation of the block diagram of the developed algorithm rules.

[0026] Figure 6 is a representative representation of the vertical load controlled anti-skid management system, which is the subject of the invention.

[0027] The drawings are not necessarily to scale and details not essential to understanding the present invention may be omitted. Furthermore, elements that are at least substantially identical or at least have substantially identical functions are indicated by the same numerals.

[0028] REFERENCE NUMBERS

[0029] 1. Wheel speed sensor

[0030] 2. Variable damping shock absorber

[0031] 3. Height potentiometer

[0032] 4. Damper trigger cable

[0033] 5. Brake pressure sensor

[0034] 6. Hydraulic modulator

[0035] 7. Wheel acceleration calculation and decision algorithm

[0036] 8. Shock absorber movement direction determination algorithm

[0037] 9. Control unit

[0038] 10. Vehicle speed and slip ratio calculation unit

[0039] 11. Throttle potentiometer

[0040] DETAILED DESCRIPTION OF THE INVENTION

[0041] In this detailed description, the vertical load controlled anti-skid management system, which is the subject of the invention, is explained only with examples that will not create any limiting effect for a better understanding of the subject.

[0042] The vertical load controlled anti-skid management system includes a wheel speed sensor (1), a variable damping shock absorber (2), a height potentiometer (3), a damper trigger cable (4), a brake pressure sensor (5), a hydraulic modulator (6), a wheel acceleration calculation and decision-making algorithm (7), a shock absorber movement direction determination algorithm (8), a control unit (9), a vehicle speed and slip ratio calculation unit (10), and a throttle potentiometer (11). The wheel speed sensor (1) enables the linear speed of the wheel to be measured and monitored. Variable damping shock absorber (2) is a part that allows the appropriate wheel load to be obtained by changing the damping level, adjusts the load on the wheels that are not driven or not in skid to bring the vehicle body to driving height in order to change the load on the skidding wheel when one or more of the vehicle's wheels are exposed to skid, thus increasing the working distance and at the same time allowing it to operate with less load, increasing the damping level to increase the wheel load and decreasing the damping level to decrease the wheel load. The wheel load change is adjusted according to the load effect matrix with the variable damping shock absorber (2). The height potentiometer (3) is the sensor that measures the direction of movement of the variable damping shock absorber (2) and determines the ride height. The damper trigger cable (4) allows the current of the shock absorber to be changed in order to change the damping level of the variable damping shock absorber (2). The brake pressure sensor (5) measures the applied brake pressure to be transmitted to the control unit (9). The hydraulic modulator (6) is the part that increases, decreases and keeps the brake pressure constant according to the commands coming from the control unit (9). Brake pressure modulation is carried out as follows. If the calculated slip is higher than the reference slip value, it reduces the brake pressure. When the calculated slip is equal to the reference slip value, it keeps the brake pressure constant. If the calculated slip is lower than the reference slip value, it increases the brake pressure. The wheel acceleration calculation and decision-making algorithm (7) determines whether the wheel is slowing down or accelerating according to the speed change of the wheel by means of the software run inside it and calculates the wheel acceleration. The shock absorber movement direction determination algorithm (8) determines the direction of the wheel load change, the compression or expansion of the wheel according to the load effect matrix by means of the software run inside it to transmit to the control unit (9). The control unit (9) is the unit that compares the wheel acceleration, shock absorber movement direction, slip rate and brake pressure according to the load effect matrix and determines the damping level. The vehicle speed and slip rate calculation unit (10) is the unit that determines the wheel speed and slip rate according to the vehicle speed through the software that is run in it, which communicates with the control unit (9). The throttle potentiometer (11) provides the change of the wheel torque by changing the throttle valve opening according to the commands transmitted from the control unit (9). The wheel torque is reduced by decreasing the throttle valve opening. The wheel torque is increased by increasing the throttle valve opening.

[0043] The control method developed to make the vertical load controlled anti-skid management system, which is the subject of the invention, more understandable, is explained through the working principle of the traditional skid control system. The system designed to eliminate the skid occurring in the wheels is called the vertical load controlled anti-skid control system. The current anti-skid control system is dependent on the slip rate and tries to prevent skidding by modulating the brake pressure and wheel torque according to the slip rate. Due to the difficulties in determining the slip rate as the road becomes slippery with the current control method, it takes a long time to prevent skidding, especially on snowy, icy and mudslick surfaces, or skidding cannot be prevented. In order to solve this problem, it is necessary to keep the slip rate at a level that can be determined accurately. For this, support is needed to keep the grip at a suitable level or prevent the grip from deteriorating. In order to keep the grip between the tire and the road at a certain level, the wheel load integrated anti-skid control system, which is the subject of the invention, has been developed. Thanks to this system, by changing the load on the wheel depending on the relationship between the brake pressure applied to the wheel or the wheel torque and the deceleration level of the wheel during skidding, a thrust force can be produced that will improve the grip of the tire on the road and push the vehicle forward. In this way, the deceleration of the skidding wheel will be fast and the skid can be ended in a shorter time.

[0044] Within the scope of applicability to industry and agriculture; the anti-skid control system, which is the subject of the invention, can be applied to all road and agricultural vehicles with air or hydropneumatic suspension systems, as well as vehicles with shock absorbers (2) providing variable damping. In air or hydropneumatic suspension systems, the wheel load can be changed by changing the air pressure and hydraulic oil pressure. Thus, the wheel load determined according to the relationship between the brake pressure or wheel torque and the wheel acceleration can be applied to the wheels by changing the air pressure or hydraulic fluid pressure. Our invention addresses the automotive sector and is an anti-skid control system that can be used in vehicles where air springs and hydropneumatic springs are used in addition to the shock absorbers (2) providing variable damping with the anti-skid control system. The fact that the anti-skid system is standard in all vehicles will allow the system to be used in a wide range of vehicles from automobiles to heavy vehicles. In addition, it can be said that it has a very wide area of use, as it can be applied to vehicles that have been manufactured or are in use.

[0045] As mentioned in the previous technique, when the brake pressure is not sufficient at the time of skidding and the wheel speed exceeds 30 km / h, the anti-skid control system starts the fuel cut-off process via the engine management system, cuts the power transferred to the wheels, reduces the wheel's momentum and tries to slow down the wheels in this way. This process continues until the acceleration slip reaches the reference value. The point to be noted here is that the fuel cut-off curve in Figure 1 almost drops to the idle level. This situation causes a serious decrease in the power transferred to the wheels. This result is one of the important bases of our invention. The point to be noted in Figure 1 is that the higher the brake pressure applied at the first moment of skidding, the higher the moment that slows down the wheels and thus the quicker it will be to prevent the wheel from skidding. For this, the factors that will ensure the locking of the wheel at high brake pressure at this moment should be taken into consideration. The most important of these points is the increase in the friction between the tire and the road during skidding. This result is another important base of our invention. In order to determine the dynamics of our invention’s anti-skid control system, the physical model and the equations obtained from this model were examined in Figure 2. The brake dynamics under the effect of vertical load changed by the shock absorber damping force are seen in the model.

[0046] The definition of the model parameters was given in Table 1:

[0047] Tablo 1. Model Parameters

[0048] Vehicle speed, V

[0049] Linear wheel speed between tire and road, V_tire

[0050] Angular acceleration of wheel,

[0051] Effective rolling radius, Re

[0052] Friction (Adhesion) force between tire and road, Fs

[0053] Vertical load, Fz

[0054] Braking force between tire and road, Fbr

[0055] Braking torque, Tb

[0056] Engine torque, Te _

[0057] From this model, two dynamic equations are obtained for the vehicle body and the wheel. The vehicle body equation is as follows:

[0058]

[0059] (1)

[0060] The equation expressing the dynamics of the wheel to which the drive and brake torque is applied is as follows.

[0061] J_T φ̈ = T_e − T_b − F_s R_e (2)

[0062] Friction force is expressed as F_s = μ(λ)F_z and F_s = PK_b equations (1) and (2) become as follows:

[0063] Mν̇_x = μ(λ)F_z (3)

[0064]

[0065] J_T φ̈ = T_e − PK_b − μ(λ)F_z R_e (K_b: Brake gain) (4)

[0066] From these equations, the vehicle body acceleration and the angular acceleration changes of the wheel are obtained as follows. Avv-“^" / / (A)(A / 7) (5)

[0067] M

[0068] Δφ̈ = (1 / J_T)(ΔT_e − ΔT_b − μ(λ)ΔF_z R_e) (6)

[0069]

[0070] J,

[0071] The positive angular acceleration of the wheel indicates that the wheel is accelerated and the negative angular acceleration indicates that the wheel is decelerated. Therefore, the point to be noted in Equation (6) is that the wheel that is spinning can be freed from the skid with negative acceleration. Thus, according to Equation 6, anti-skid control systems used today either increase the brake pressure, reduce the engine torque or intervene with a combination of both to reduce the wheel acceleration. Equation 6 can be rearranged according to the types of intervention. For only brake intervention, equation 6 becomes like equation 7. Since the skid is controlled only by the brake torque in Equation 7, the engine torque component ΔT_e becomes zero.

[0072] Δφ̈ = (1 / J_T)(−ΔT_b − μ(λ)ΔF_z R_e) (7)

[0073]

[0074] According to equation 7, the deceleration of the skidding wheel, that is, negative wheel acceleration, can be provided by changing the wheel load in addition to the braking torque. At the same time, the decrease in the intensity of the braking torque can be provided by increasing the wheel load. For only engine torque intervention, equation 7 becomes like equation 8. Since the skidding is controlled only by engine torque intervention in equation 8, the brake torque component ΔT_b becomes zero.

[0075] Δφ̈ = (1 / J_T)(ΔT_e − μ(λ)ΔF_z R_e) (8)

[0076]

[0077] JTAccording to Equation 8, the deceleration of the skidding wheel, that is, the negative acceleration of the wheel, can be provided by the decrease in the engine torque as well as the change in the wheel load. At the same time, it is seen that the decrease in the engine torque can be provided by the change in the wheel load. Equation 6 can be used for the joint intervention of the engine torque and the brake torque. According to Equation 6, it is seen that the skidding can be intervened with the combination of engine and brake torques, and that the level of brake and engine torque can be controlled by the change in the wheel load during this intervention. As a result of the above examinations, it can be seen that the increases and decreases in the brake torque and engine torque in all interventions made to the skidding wheel can be controlled by the change in the wheel load. In this way, the increase in the vertical load will build up the brake pressure during the skidding that occurs at wheel speeds lower than 30 km / h, and it will also decrease the reductions in the engine torque at wheel speeds higher than 30 km / h. At the same time, according to Equation 5, the increase in the vertical load shows that the acceleration of the vehicle can be increased. In this way, the vertical load increase can regulate both the angular acceleration of the wheel and the linear acceleration of the vehicle body.

[0078] Design of Control Algorithm

[0079] Anti-skid systems change the brake pressure and engine torque according to the acceleration slip of the wheel via the brake pressure. Acceleration slip is a function of the friction coefficient and is expressed as follows.

[0080]

[0081] Vwheel

[0082] According to Equation 9, the acceleration slip takes values between 0 and 1. When the slip value is 1, the wheel is in full skid and at this moment the vehicle's translational speed, that is, the acceleration is zero. When the slip value is 0, the wheel rotates without slipping and the vehicle speed reaches its maximum value. At this moment, no brake or drive torque is applied to the wheel. If drive or brake torque is applied to the wheel, a difference will occur between the wheel speed and the vehicle speed, resulting in slip. When drive torque is applied to the wheel, the slip change becomes as in Figure 3.

[0083] As seen in Figure 3, traction at the moment of drive depends on the road conditions and acceleration slip takes maximum values between 0.1 and 0.3. For example, when the slip is 0.15 on an icy road, maximum traction is achieved. Maximum traction is approximately 0.1. This value indicates that 10% of the drive force to be applied on an icy road will be used to move the vehicle. Therefore, the skidding speed on icy roads is higher than on other roads. In order to prevent this skidding, the braking force applied to the road by the brake system will be very high compared to the friction force between the tire and the road, so the wheel will constantly skid but will not be able to move the vehicle. For this, the friction force must be increased. Loading the drive wheels of a skidding vehicle or seating the occupants of the skidding vehicle on the seats on the drive wheel or making a jumping movement on the axle to which the drive wheel is attached are real-life examples of this situation. In addition, pouring gravel under a tire that skids in mud is also a real-life application to increase friction force. In this context, the easiest way to increase the friction force between the tire and the road is to increase the vertical load on the wheel, as seen in Figure 4. Figure 4 shows how the increase in load changes the friction force depending on the slip. As seen in Figure 4, the friction force also increases as the vertical load increases at the same slip value. According to the graph given in Figure 4, when the vertical load of the wheel that skids is increased, higher braking force can be applied to the wheel at the same slip value. In this way, the tire will receive better force from the road and will start to move on the road without skidding or with less skidding. Thus, the increased vertical load will be able to apply higher brake pressure on the same road and allow the wheel to get out of skidding more quickly. Considering that the wheel load change is obtained with variable damping force, the rules of the control algorithm designed according to the above findings are as follows. The definitions of the variables used in this algorithm are as follows:

[0084] • AP>0 and AP<0, respectively, brake pressure increases and decreases,

[0085] • ATe >0 and ATe <0, respectively, engine torque increases and decreases,

[0086] • Aco>0 and Aco<0, respectively, wheel acceleration change, i.e. wheel acceleration and deceleration,

[0087] • AFz>0, wheel load is increased by increasing the damping force of the shock absorber, • AFz<0, wheel load is reduced by decreasing the damping force of the shock absorber, • AFz=0, respectively, wheel load is kept constant without changing the damping force of the shock absorber,

[0088] • S, calculated acceleration slip Se, the reference acceleration slip where maximum grip is achieved. (Note: For this algorithm, it is considered that the vehicle is driven on a snowy road. Therefore, the slip threshold value Se is considered as 20%). In the rules of this invention; The relationships between the calculated acceleration slip and the reference acceleration slip are defined as follows:

[0089] 1. S> Se indicates that the wheel's grip is weakening and approaching the locking limit, 2. S=Se indicates that the wheel is rotating with maximum grip,

[0090] 3. S< Se indicates that the wheel's grip is increasing but has not yet reached maximum.

[0091] While the rotation dynamics of the wheel around its own axis are in the three different slip ranges defined above, the algorithm assumes that the anti-skid control system calculates the pressure change 20 times per second. In other words, the control cycle starts again every 50ms. The goal here is to obtain the S=Se equation in each cycle with the wheel load change and thus to bring the grip of all the drive wheels to the same level. If the linear speed of the wheel is below 30 km / h, the following algorithm should be used. At these speeds, the following conditions must be met without applying the algorithm the brake pressure change and the acceleration of the wheel as follows in flat road and uphill situations for the wheel load change.

[0092] Conditions to be met before skid management on flat roads and uphill:

[0093] In flat roads and uphill situations, before using the control algorithm developed for skid management, the load on the axle wheels that are not driven or not skidding should be increased by means of shock absorbers to bring the vehicle body to the ride height, in other words, to make the vehicle body parallel to the road, and should be kept constant at the ride height. Thus, the following rules are applied for the load control that will manage the skid, starting from the ride height level.

[0094] When AP>0 & Aco<0, that is, when the wheel slows down with the increase in brake pressure while controlling the skid, the wheel load should change according to the acceleration slip value as follows:

[0095] • If the slip value S of the skidding wheel is greater than the reference slip value Se, that is, if the wheel is spinning at a speed close to skidding, the wheel load should be increased. Thus, if S> Se, AFz>0 should be. (Thanks to this rule, the load acting on the skidding wheel can be increased and the wheels can be slowed down faster by applying higher brake pressure to the wheels. In this way, skidding can be stopped in a shorter time).

[0096] • If the acceleration slip value S of the skidding wheel is equal to the reference slip value Se, that is, if the wheel is spinning at maximum grip, the wheel load should be kept constant. Thus, if S=Se, AFz=0 should be. (Thanks to this rule, the load acting on the skidding wheel can be kept constant and maximum grip can be achieved. Under these conditions, when the wheels move back and forth while skidding and there is a change in the wheel load, the damping level of the shock absorber should be controlled in a way that keeps the wheel load constant).

[0097] • If the acceleration slip value S of the skidding wheel is smaller than the reference slip value Se, i.e. if the wheel is rotating slower, the wheel load should be reduced. Thus, if S< Se, AFz<0. (Thanks to this rule, the load acting on the skidding wheel can be reduced, the effect of the brake pressure can be increased, and higher braking effect can be achieved, and thus skidding can be stopped in a shorter time).

[0098] When AP>0 & Aco>0, that is, when controlling the skid during skidding, if the wheel does not slow down but accelerates despite the increase in brake pressure, that is, if the wheel cannot be slowed down to the desired level with insufficient brake pressure, the wheel load should change according to the acceleration-slip change as follows:

[0099] • If the slip value S of the skidding wheel is greater than the reference slip value Se, that is, if the wheel is rotating at a speed close to skidding, the wheel load should be reduced. Thus, if S> Se, AFz<0 should be. (Thanks to this rule, the load acting on the skidding wheel will be reduced, the brake effect will be reduced with decreased friction and as a result, a higher brake torque will be applied to the wheels than the friction torque, and the wheels will be slowed down faster. Thus, skidding will be stopped in a shorter time).

[0100] • If the acceleration slip value S of the skidding wheel is equal to the reference slip value Se, that is, if the wheel is rotating at maximum grip, the wheel load should be kept constant. Thus, if S=Se, AFz=0 should be. (Thanks to this rule, the load acting on the skidding wheel will be kept constant and maximum grip will be achieved. Under these conditions, when there is a change in the wheel load with the wheels moving back and forth during skidding, the damping level of the shock absorber should be controlled in a way that keeps the wheel load constant).

[0101] • If the acceleration slip value S of the skidding wheel is smaller than the reference slip value Se, i.e. if the wheel is rotating slower, the wheel load should be reduced. Thus, if S< Se, AFz<0. (Thanks to this rule, the load acting on the skidding wheel can be increased and higher brake pressure can be applied to the wheels, thus stopping the skidding in a shorter time).

[0102] If the linear speed of the wheel is above 30 km / h, the engine torque change and the acceleration of the wheel should be taken as reference for the wheel load change as follows. The wheel load change rules according to the engine torque change are similar to the rules obtained according to the brake pressure change given above. Here, the main basis of the rules obtained according to the engine torque is to prevent excessive decrease in the engine torque and to slow down the wheels by means of wheel load integration and engine torque management.

[0103] When ATe<0 & Aco<0, that is, when the wheel slows down with the decrease in engine torque while controlling the skid, the wheel load should change as follows:

[0104] • If the slip value S of the skidding wheel is greater than the reference slip value Se, that is, if the wheel is rotating at a speed close to skidding, the wheel load should be increased. Thus, if S> Se, AFz<0 should be. (Thanks to this rule, the load acting on the skidding wheel will be reduced and the engine torque will be reduced more slowly, and as a result, the wheels will slow down and finally the wheels will be freed from skidding at a higher engine torque, that is, at a higher engine speed).

[0105] • If the acceleration slip value S of the skidding wheel is equal to the reference slip value Se, that is, if the wheel is rotating at maximum grip, the wheel load should be kept constant. Thus, if S=Se, AFz=0 should be. (Thanks to this rule, the load acting on the skidding wheel will be kept constant and maximum grip can be achieved. Under these conditions, when the wheels move back and forth while skidding and there is a change in the wheel load, the damping level of the shock absorber should be controlled in a way that keeps the wheel load constant).

[0106] • If the acceleration slip value S of the skidding wheel is smaller than the reference slip value Se, that is, if the wheel is rotating slower, the wheel load should be reduced. Thus, if S< Se, AFz<0. (Thanks to this rule, the load acting on the skidding wheel is reduced, the effect of the decrease in engine torque is increased, and the wheels can be slowed down with a higher engine speed, and thus skidding can be stopped in a shorter time).

[0107] When ATe<0 & Aco>0, that is, If the wheel does not slow down at the desired rate due to the decrease in engine torque while controlling the skid, the wheel load should change as follows:

[0108] • If the slip value S of the skidding wheel is greater than the reference slip value Se, that is, if the wheel is rotating at a speed close to skidding, the wheel load should be increased. Thus, if S> Se, AFz<0 should be. (Thanks to this rule, the wheels can be slowed down faster by increasing the load acting on the skidding wheel, by reducing the moment of the wheels faster. In this way, skidding can be stopped in a shorter time).

[0109] • If the acceleration slip value S of the skidding wheel is equal to the reference slip value Se, that is, if the wheel is rotating at maximum grip, the wheel load should be kept constant. Thus, if S=Se, AFz=0 should be. (Thanks to this rule, the load acting on the skidding wheel can be kept constant and maximum grip can be achieved. Under these conditions, when there is a change in the wheel load with moving the wheels back and forth during skidding, the damping level of the shock absorber should be controlled in a way that keeps the wheel load constant).

[0110] • If the acceleration slip value S of the skidding wheel is smaller than the reference slip value Se, i.e. if the wheel is rotating slower, the wheel load should be decreased. Thus, if S< Se, AFz<0. (Thanks to this rule, the load acting on the skidding wheel will be reduced, the effect of the decrease in wheel torque will be increased, and a higher deceleration effect will be achieved, and thus skidding will be stopped in a shorter time).

[0111] As a result, the block diagram of the developed algorithm rules is as in Figure 5. In order to apply the above control rules, the operating principle of the system should be as follows.

[0112] • When the linear speed of the wheel is below 30 km / h, the brake pressure is firstly increased for the wheel that skids, then the brake pressure and the wheel acceleration are compared, and the wheel load change is selected and applied according to the acceleration-slip value.

[0113] • When the linear speed of the wheel is above 30 km / h, the wheel torque is firstly reduced for the wheel that skids, then the wheel torque and the wheel acceleration are compared, and the wheel load change is selected and applied according to the acceleration-slip value. The wheel load change depends on the direction of movement of the shock absorber, and the wheel loads should change according to the load effect matrix below.

[0114] Shock absorber damping level selection

[0115] Req 'ueste,d wheel load

[0116] change Comprression movement _ Expansion movement Decrease in wheel ioad Soft Hard

[0117] Increase in wheel load Hard Soft

[0118] Table 2. Illustration of the change in wheel load according to the shock absorber damping level

[0119] In the load effect matrix in Figure 5, the wheel loads should change according to the shock absorber movement direction as follows:

[0120] 1. If the wheel load is requested to be increased while the shock absorber is compressing during the skid management, the shock absorber level should be set to hard, and if the wheel load is requested to be reduced, the shock absorber level should be set to soft.

[0121] 2. If the wheel load is requested to be increased while the shock absorber is expanding, the shock absorber level should be set to soft, and if the wheel load is requested to be reduced, the shock absorber level should be set to hard.

[0122] Thus, in order to realize the wheel load change integrated skid management during skidding, the structure of the system should be as in Figure 6.

[0123] According to the diagram in Figure 6, the data required for the control system are:

[0124] • Brake pressure pressure change rate (AP) is obtained by taking the derivative of the brake pressure measured from the brake pressure sensor (5), • Engine torque change rate (ΔTe) is obtained by taking the derivative of the engine torque determined by the throttle potentiometer (11),

[0125] • Wheel acceleration (Δω) is obtained by taking the derivative of the wheel speed measured by the wheel speed sensors (1),

[0126] • Slip rate (S) is obtained by using the wheel speeds measured from the wheel speed sensors (1),

[0127] • Shock absorber movement direction is obtained with the distance measured by the height potentiometer (3).

[0128] The working principle of the wheel load integrated skid control system:

[0129] When one or more of the vehicle's wheels are exposed to skidding, in order to change the load on the skidding wheel more quickly, the load of the wheels that are not driven or not in skid is adjusted with the variable damping shock absorber (2) in a way that brings the vehicle body to the ride height. In this process, the wheel load is either increased or decreased until the ride height is reached and kept constant at the ride height. The ride height is determined with the height potentiometer (3). In this way, the vehicle body that applies the load on the wheels is also brought to the ride height. In this way, the working distance of the shock absorber is increased and at the same time, the shock absorber can be operated with less load. After this process is completed, the intervention of the skidding wheel is started. For this purpose, the wheel acceleration calculation and decision-making algorithm (7) uses the linear speed of the wheel measured by the wheel speed sensor (1) and the wheel acceleration, vehicle speed and slip rate calculation unit (10) determines the vehicle speed, linear speed of the wheel and the slip rate of the skidding wheel from all wheel speeds. If the linear speed of the wheel is lower than 30 km / h, the throttle valve opening is firstly decreased according to the slip calculated for the skidding wheel and the engine torque is reduced. When the linear speed of the wheel is higher than 30 km / h, the brake pressure is firstly increased by the hydraulic modulator (6). Immediately after this intervention, the existing brake pressure is measured by the brake pressure sensor (5) and the brake pressure change rate or the engine torque change rate measured by the throttle valve potentiometer (11) according to the throttle valve opening is determined by the shock absorber movement direction determination algorithm (8) and the compression or expansion of the wheel is determined and all information is sent to the control unit (9) as shown in Figure 6. The brake pressure change rate or the engine torque change rate according to the linear speed of the wheel is compared with the wheel acceleration in the control unit (9) and the wheel load change is determined according to the slip value calculated by the vehicle speed and slip rate calculation unit (10). Here, the decision is given regarding increasing or decreasing the wheel load. The damping level that will provide the decided wheel load change is determined by the load effect matrix in the control unit (9). The intervention is completed by triggering the current with the damper trigger cable (4) according to the determined damping. Subsequent interventions are continued in this way to ensure that the wheel falls out of the skid.

Claims

CLAIMS1. A vertical load controlled anti-skid management system that increases, decreases or keeps the vertical force of the wheels on the road constantly or intermittently by changing the damping level according to the change in brake pressure and engine torque during skidding in single-axle or multi-axle drive vehicles and thus prevents the wheels from skidding or reduces the skidding speed, and characterized by comprising;• at least one wheel speed sensor (1) that allows the linear speed of the wheel on the vehicle to be measured,• variable damping shock absorber (2) that allows the appropriate wheel load to be obtained by changing the damping level in order to increase the working distance of the wheel and to ensure that the wheel operates with less load, and adjusts the load of the wheels that are not driven or not in skid to bring it to the ride height of the vehicle body in order to change the load on the skidding wheel when one or more of the vehicle's wheels are subject to skidding,• height potentiometer (3) that measures the direction of movement of the variable damping shock absorber (2) and determines the ride height, • damper trigger cable (4) that allows the current of the shock absorber to be varied to change the damping level of the variable damping shock absorber (2),• brake pressure sensor (5) that measures the applied brake pressure to be transmitted to the control unit (9),• hydraulic modulator (6) that increases, decreases or keeps the brake pressure constant according to the commands coming from the control unit (9), • wheel acceleration calculation and decision-making algorithm (7) that calculates the wheel acceleration with the data which it receives from the wheel speed sensor (1) through the software run in it and determines whether the wheel is slowing down or accelerating according to the change in wheel speed,• shock absorber movement direction determination algorithm (8) that determines the direction of wheel load change, compression or expansion of the wheel according to the load effect matrix through software run inside it to transmit to the control unit (9),• vehicle speed and slip rate calculation unit (10) that determines the slip rate according to the wheel speed and vehicle speed through software run inside it, which communicates with the control unit (9),• throttle potentiometer (11) that reduces the wheel torque by decreasing the throttle valve opening or increases the wheel torque by increasing the throttle valve opening according to the commands received from the control unit (9) • The control unit (9) which communicates with the wheel speed sensor (1), variable damping shock absorber (2), height potentiometer (3), damper trigger cable (4), brake pressure sensor (5), hydraulic modulator (6), wheel acceleration calculation and decision-making algorithm (7), shock absorber movement direction determination algorithm (8), vehicle speed and slip ratio calculation unit (10) and throttle potentiometer (11), instantly compares the wheel acceleration, variable damping shock absorber (2) movement direction, slip ratio and brake pressure according to the load effect matrix and determines the damping level, and sends commands to the variable damping shock absorber (2), damper trigger cable (4), hydraulic modulator (6) and throttle potentiometer (11) according to the damping level it determines.

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