CN105752325B - Control Method for Airplane Antiskid Braking System based on brake torque feedback - Google Patents

Abstract

The application is related to a kind of Control Method for Airplane Antiskid Braking System based on brake torque feedback, including：Detect the brake torque of airplane wheel and the rotating speed of airplane wheel；The actual slip factor is determined based on brake torque and rotating speed；Compare the actual slip factor and sliding factor threshold；If the actual slip factor is equal to sliding factor threshold, the threshold value of the sliding factor is updated；And reduce brake torque so that the actual slip factor is less than the sliding factor threshold after updating.According to the scheme of the application, wheel can be avoided to skid, improve antiskid brake efficiency of the aircraft under complicated runway surface situation.

Description

Aircraft antiskid braking control method based on braking torque feedback

technical field

The present application relates to the field of aviation technology, in particular to an aircraft anti-skid braking control method based on braking torque feedback.

Background technique

The take-off and landing of an aircraft are the phases where aircraft accidents occur frequently. The anti-skid brake system is an important airborne equipment of the aircraft, which has an important impact on the safety of the aircraft take-off and landing. It is of great significance to improve the safety and reliability of aircraft to require that the aircraft can still land safely and stop under complex runway environmental conditions.

Aircraft anti-skid braking system is a complex nonlinear system with uncertainty. There are many nonlinear factors in the system, which directly affect the performance of anti-skid braking. The landing and rolling process of the aircraft takes a short time, so the anti-skid braking system is required to work stably, quickly and accurately to ensure the safety of the aircraft [2]. The performance of the anti-skid braking system is affected by many factors, such as whether the runway surface is grooved, the condition of the runway surface (dry, wet or snow-covered, etc.), changes in aircraft speed, and tire inflation pressure. Essentially, these factors affect the bond and rolling resistance of the tires of the aircraft's braked wheels to the runway surface. The main purpose of the anti-skid braking system is to make full use of the binding force provided by the runway to stop the aircraft in the shortest possible distance.

The change of the surface condition of the runway is a serious external disturbance to the aircraft anti-skid braking system. For example, when the combination coefficient of the surface of the runway where the wheel is located changes from high to low, the wheel slips or even locks up due to the sharp decrease in the combined torque. This requires the anti-skid brake control box to respond in time to make the machine The rotation speed is restored. Therefore, the adaptability of the braking control algorithm to different runway surface conditions and the robustness when the runway surface conditions change directly affect the anti-skid braking effect.

Judging from the published aircraft anti-skid braking control algorithm, it mainly relies on the measurement of the angular velocity or angular acceleration of the main engine wheel of the aircraft at present, and cooperates with the estimated airframe speed to make the aircraft Slow down and stop according to the desired index. For a single runway surface condition, this type of control method can obtain better antiskid braking effect. However, due to the different indicators corresponding to different runway surface states, this kind of control method lacks the adaptability to the change of runway surface state.

Contents of the invention

A brief overview of the application is given below in order to provide a basic understanding of certain aspects of the application. It should be understood that this summary is not an exhaustive summary of the application. It is not intended to identify key or critical elements of the application, nor is it intended to limit the scope of the application. Its purpose is merely to present some concepts in a simplified form as a prelude to the more detailed description that is discussed later.

A main purpose of the present application is to provide an aircraft anti-skid braking control method based on braking torque feedback, aiming to solve the above technical problems.

In the first aspect, the present application provides an aircraft anti-skid braking control method based on braking torque feedback, including: detecting the braking torque of the aircraft wheel and the rotational speed of the aircraft wheel; determining the actual slip factor based on the braking torque and the rotational speed; comparing the actual The slip factor and the slip factor threshold; if the actual slip factor reaches the slip factor threshold, update the slip factor threshold; and reduce the braking torque so that the actual slip factor is smaller than the updated slip factor threshold.

The aircraft anti-skid braking control method based on braking torque feedback of the present application determines the actual slip factor by detecting the braking torque of the aircraft wheel and the rotational speed of the aircraft wheel, and continuously updates the slip factor based on the comparison between the actual slip factor and the slip factor threshold. The shift factor is used to keep the binding force between the wheel and the runway near the peak value of the binding force, thereby avoiding the wheel slipping and improving the anti-skid braking efficiency of the aircraft under complex runway surface conditions.

In some embodiments, the aircraft anti-skid braking control method based on braking torque feedback of the present application also increases the braking torque when the combined force F _lm meets F _lm <k _ad F _slip , thereby keeping the aircraft wheel away from the adhesion area and improving The anti-skid braking efficiency of the aircraft under complex runway surface conditions.

In some embodiments, the aircraft anti-skid braking control method based on braking torque feedback of the present application also re-updates the peak value of the combined force when the difference ΔF _slip between two adjacent updated peak values of the combined force is not within the preset value range, So that when the combination coefficient of the runway changes, the braking torque can be adjusted accordingly, so that the combination force can be kept near the peak value of the combination force, and the anti-skid braking efficiency of the aircraft under complex runway surface conditions can be improved.

Description of drawings

The above and other objects, features and advantages of the present application will be more easily understood with reference to the following description of the embodiments of the present application in conjunction with the accompanying drawings. The components in the figures are only intended to illustrate the principles of the application. In the drawings, the same or similar technical features or components will be denoted by the same or similar reference numerals.

Fig. 1 is the schematic flowchart of an embodiment of the aircraft anti-skid braking control method based on braking torque feedback of the present application;

Fig. 2 is a schematic structural diagram of an aircraft braking device that can be used to collect and detect braking torque;

Fig. 3 A is the actual relationship curve between the slip factor and the braking torque;

Fig. 3B is the relationship curve between the slip factor and the braking torque that can distinguish whether the wheel is in a locked state;

Fig. 4A is after adopting the method of the present embodiment, the curve graph of aircraft body speed and aircraft wheel speed with time;

Fig. 4B is a graph corresponding to the binding force and the peak value of the binding force over time corresponding to Fig. 4A;

Fig. 5A is after adopting the method of the present embodiment, when the runway changes from a high combination coefficient to a low combination coefficient, the speed of the aircraft body and the speed of the aircraft wheel change with time;

Figure 5B is a graph of the binding force and the peak value of the binding force as a function of time corresponding to Figure 5A

Fig. 6A is after adopting the method of the present embodiment, when the runway changes from a low combination coefficient to a high combination coefficient, the speed of the aircraft body and the speed of the aircraft wheel change with time;

FIG. 6B is a graph corresponding to FIG. 6A of the binding force and the peak value of the binding force over time.

detailed description

Embodiments of the present application are described below with reference to the drawings. Elements and features described in one drawing or one embodiment of the present application may be combined with elements and features shown in one or more other drawings or embodiments. It should be noted that representation and description of components and processes that are not relevant to the present application and known to those of ordinary skill in the art are omitted from the drawings and descriptions for the purpose of clarity.

Referring to FIG. 1 , it is a schematic flowchart of an embodiment of an aircraft anti-skid braking control method based on braking torque feedback of the present application.

The aircraft anti-skid braking control method based on braking torque feedback of the present embodiment includes:

Step 110, detecting the braking torque of the aircraft wheel and the rotational speed of the aircraft wheel.

In some optional implementation manners, the rotational speed of the aircraft wheel may be detected and collected, for example, by a rotational speed sensor installed on the axle of the aircraft wheel. The braking torque of the aircraft wheel, for example, can be detected and collected by using a braking device as shown in FIG. 2 .

As shown in FIG. 2 , the static disk 210 of the braking device is connected to the wheel shaft 230 through the flange 220 , and the left side of the wheel shaft is connected to the landing gear pillar. When the aircraft performs anti-skid braking, the high-pressure oil at the outlet of the anti-skid brake valve pushes the piston 240 to compress the static disc 210 and the dynamic disc. Braking torque, on the other hand, applies torque to the wheel shaft through the static disc 210 and the flange 220 , so the torque on the wheel shaft can be measured through the strain gauge 250 arranged on the wheel shaft 230 , thereby obtaining the braking torque.

Step 120, determining an actual slip factor based on the braking torque and the rotational speed.

In order to make full use of the accurately measured physical quantities and known structural parameters to construct the slip factor, and to clearly express the different characteristics of the wheel in the attachment zone and the ideal working zone and the slip zone, the slip factor expression is as follows: Formula 1.1 Shown:

Among them, η is the slip factor, F _lm is the binding force between the wheel and the runway, r is the radius of the wheel, and M _b is the braking torque.

According to the dynamic equation of the wheel, when the rolling friction moment of the wheel is neglected, there is:

where ω is the speed of the wheel. J is the moment of inertia of the wheel, which is a known structural parameter.

Generally speaking, the relationship between the slip factor and the braking torque satisfies the curve shown in FIG. 3A . In FIG. 3A , the peak of the curve corresponds to the wheel speed being 0, that is, the corresponding slip factor when locking occurs.

It can be seen from FIG. 3A that the slip factor will change drastically when the aircraft wheel is about to slip (that is, when the curve approaches the braking torque corresponding to the peak of the curve from the origin direction). Therefore, if the above-mentioned formula (1.2) is directly used to calculate the slip factor η, it will not be possible to judge that the state of the aircraft corresponding to the slip factor at this time is before reaching the peak value of the slip factor (that is, the aircraft has not yet locked up). The value is still the value after reaching the peak value of the slip factor (that is, the aircraft is locked). Therefore, it is necessary to increase the auxiliary judgment standard of the wheel speed. That is to say, if the slip factor η calculated by the formula (1.2) is greater than the slip factor threshold, and the wheel speed satisfies ω<ω _min , the value of the slip factor η is set Values that cause malfunctions, for example, η at this time can be set to 1. Here, ω _min is a preset value close to 0.

The relationship curve between the corrected slip factor and the braking torque is shown in Fig. 3B by assisting in judging the wheel speed.

Therefore, by detecting the machine rotation speed ω and the braking torque M _b , the actual slip factor η can be determined by combining the formula (1.2) and auxiliary judgment and adjustment of the wheel speed.

Step 130, comparing the actual slip factor with the slip factor threshold.

Please continue to refer to FIG. 3B . It can be seen from Figure 3B that when the wheel is working in the adhesion zone (that is, the actual braking torque is less than and far from the braking torque corresponding to the peak value of the slip factor, and the aircraft does not skid), the slip factor η remains very small range changes. And once it enters the skidding region (that is, the actual braking torque is less than but close to the braking torque corresponding to the peak value of the slip factor, and the aircraft starts to skid), the value of the slip factor η increases rapidly. This feature provides a relatively clear and loose judgment standard for judging the working area of the wheel. Therefore, by reasonably setting the slip factor threshold η _slip , it can be ensured that the value of η _slip is far away from the value range of η in the slipping region.

The slip factor threshold η _slip can be selected within a relatively loose range. This is caused by the characteristics of the slip factor. First of all, because the slip factor η value difference between the slipping state and the non-slipping state of the wheel is obvious, there is a large margin when designing the value of η _slip ; secondly, the value of η _slip can be designed The purpose of is to make the aircraft wheel in the ideal working area, which broadens the selection range of slip factor threshold η _slip . When the aircraft wheel is in the ideal working area, the binding force between the aircraft wheel and the runway is close to the peak value F _slip of the binding force, and the wheel does not slip.

Step 140, if the actual slip factor reaches the slip factor threshold, update the slip factor threshold, and reduce the braking torque in step 150 so that the actual slip factor is smaller than the updated slip factor threshold.

In practical applications, when the aircraft has not yet landed, generally the relevant information of the runway surface cannot be obtained, therefore, the slip factor corresponding to the peak binding force F _slip cannot be obtained accurately. Therefore, the initial value of a slip factor threshold can be set first, and the slip factor threshold can be updated in a certain way, so that the slip factor threshold is constantly approaching the real slip factor threshold, that is, the combination with the real The slip factor corresponding to the peak force F _slip .

For example, when the actual slip factor is greater than or equal to the slip factor threshold, the peak coupling force may be updated based on the braking torque and the rotation speed, and the slip factor threshold may be updated based on the updated peak coupling force.

Specifically, the peak binding force is updated by the following formula (1.3):

Among them, F _lm is the bonding force, and r is the radius of the aircraft wheel.

The binding force F _lm when the actual slip factor is equal to the slip factor threshold is the binding force peak value F _slip .

After updating the peak binding force F _slip by the formula (1.3) shown above, the threshold value of the slip factor can be updated by the following formula (1.4):

Wherein, η _ss is the initial value of slip factor threshold value, and its specific value can be an empirical value; F _ss is the initial value of the binding force set in advance, and its specific value can be an empirical value; η _slip is the slip after updating Factor threshold, k ₁ , k ₂ , k ₃ , k ₄ are preset coefficients, and satisfy:

-1<k ₁ <0;

0<k ₂ <1;

-1<k ₃ <0;

0<k ₄ <1.

Through this update process, the slip factor can gradually approach the real slip factor threshold, so that the binding force between the wheel and the runway approaches the real peak binding force, thereby maximizing the braking efficiency.

In this way, if the current braking torque reaches or exceeds the current slip factor threshold, the braking torque is reduced, thereby avoiding wheel skidding and improving the anti-skid braking efficiency of the aircraft under complex runway surface conditions.

Optionally, the aircraft antiskid braking control method based on braking torque feedback in this embodiment may further include:

Step 160, determine the binding force F _lm based on the braking torque and the rotational speed, and judge whether the binding force F _lm satisfies F _lm <k _ad F _slip .

Step 170, if F _lm <k _ad F _slip is satisfied, increase the braking torque.

Wherein, k _ad is a preset adhesion coefficient, and satisfies 0.5<k _ad <1.

Through the above steps 160 and 170, the aircraft wheels can be kept away from the adhesion area, avoiding the situation that the wheels do not fully utilize the bonding force that the tires can produce, and further improve the anti-skid braking efficiency of the aircraft under complex runway surface conditions.

However, in practical applications, the combination coefficient of the runway does not remain constant when the aircraft lands. Here, the bond coefficient of the runway can characterize the coefficient of friction that the runway can provide to the aircraft wheels. When the combination coefficient of the runway is different, the relationship between the braking torque and the slip factor will also change accordingly.

For example, when the binding coefficient of the runway surface changes from low to high, the braking torque remains unchanged, but the binding force will increase significantly. Conversely, when the binding coefficient of the runway surface changes from high to low, the braking torque remains constant, and the binding force will decrease significantly.

Therefore, in order to capture significant changes in the runway surface binding coefficient, so that the braking torque can be quickly adjusted to the vicinity of the peak binding force corresponding to the current binding coefficient, the aircraft anti-skid braking control method based on braking torque feedback in this embodiment may further include the following A step of:

Step 180 , judging whether the difference ΔF _slip between two adjacent updated binding force peak values is within a preset value range.

Step 190, if not, update the peak binding force based on the following formula (1.5), and update the threshold of the slip factor based on the updated peak binding force:

Here, the preset numerical range may be, for example, a numerical interval, for example, [-ΔF _th1 , ΔF _th2 ]. When determining the value of ΔF _th1 and ΔF _th2 , the value change of bonding force caused by normal anti-skid braking and external disturbance can be considered, and the value of ΔF _th1 and ΔF _th2 is greater than the value change of bonding force caused by normal anti-skid braking and external disturbance scope.

Next, the aircraft anti-skid braking control method based on braking torque feedback of this embodiment will be described in conjunction with the simulation curves of FIGS. 4A-6B , so as to make its advantages more obvious and prominent.

Referring to shown in Figure 4A, after adopting the method of this embodiment, the speed of the aircraft body and the speed of the aircraft wheel change with time. picture.

It can be seen from Fig. 4A and Fig. 4B that the body speed decreases steadily during the entire anti-skid braking process, and the wheel speed fluctuates under the brake force of the loose-brake-loose cycle, which does not cause the wheel to slip, and the anti-skid brake is turned on During the process, no wheel lock occurred. After the body speed is lower than a certain value, the anti-skid brake control is cut off, and under the algorithm control based on the binding force feedback, the wheels work near the peak value of the binding force that the runway can provide, until the body speed is lower than a certain speed, the anti-skid brake is turned off , the wheel is locked, and the binding force is reduced.

Referring to Fig. 5A, after adopting the method of the present embodiment, when the runway changes from a high combination coefficient to a low combination coefficient, the speed of the aircraft body and the speed of the aircraft wheel change with time, and Fig. 5B is a graph corresponding to Fig. 5A Curves of binding force and peak binding force over time.

It can be seen from Fig. 5A and Fig. 5B that when the runway changes from a high binding coefficient to a low binding coefficient, the speed of the aircraft body during the whole anti-skid braking process decreases steadily, and the wheel speed is due to the braking force in the release-brake-release cycle. Fluctuations occurred under the action, and the change of the runway state had a significant impact on the deceleration rate of the airframe and the sliding component in the wheel motion, but did not cause the wheel to slip, and no wheel lock occurred during the opening of the anti-skid brake. After the state of the runway changes, use the same method to detect a new peak binding force; under the control of the algorithm based on binding force feedback, the wheels work near the peak binding force that the runway can provide until the body speed is lower than 5.5m /s, the anti-skid brake is turned off, the wheel is locked, and the binding force is reduced. After the state of the runway changes, the method of this embodiment detects that the wheels are slipping, firstly reduce the brake pressure command, thereby reducing the braking torque, so that the wheels return to the attached working area, and then increase the brake pressure command to search and combine online again force peak, a new ideal operating point is detected again.

Referring to Fig. 6A, after adopting the method of this embodiment, when the runway changes from a low combination coefficient to a high combination coefficient, the speed of the aircraft body and the speed of the aircraft wheel change with time, and Fig. 6B is a combination corresponding to Fig. 6A Graph of peak force and binding force versus time.

From Figure 6A and Figure 6B, it can be seen that when the runway changes from a low combination coefficient to a high combination coefficient, the body speed of the entire anti-skid braking process decreases steadily, and the wheel speed is due to the braking force in the release-brake-release cycle The change of the runway state has an impact on the deceleration rate of the airframe and the sliding component in the wheel motion, but it did not cause the wheel to slip, and the wheel lock did not occur during the activation of the anti-skid brake. The slip ratio gradually increases at low speeds, but the slip component in the wheel motion is much smaller compared to a runway with low binding coefficient. Under the low-speed working condition, the working point of the wheel gradually moves toward the positive direction of the horizontal axis, which indicates that the sliding component in the wheel movement gradually increases; after the state of the runway changes, a new peak value of the binding force is detected by the same method; Under the control of the combined force feedback algorithm, the wheels work near the peak value of the combined force that the runway can provide, until the body speed is lower than 5.5m/s, the anti-skid brakes are turned off, the wheels are locked, and the combined force decreases.

The above description is only a preferred embodiment of the present application and an illustration of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to the technical solution formed by the specific combination of the above-mentioned technical features, but should also cover the technical solution formed by the above-mentioned technical features without departing from the inventive concept. Other technical solutions formed by any combination of or equivalent features thereof. For example, a technical solution formed by replacing the above-mentioned features with technical features with similar functions disclosed in (but not limited to) this application.

Claims (6)

1. a kind of aircraft antiskid braking control method based on braking torque feedback, it is characterized in that, comprising: Detect the braking torque of the aircraft wheel and the speed of the aircraft wheel; determining an actual slip factor based on the braking torque and the rotational speed; comparing said actual slip factor with a slip factor threshold; if the actual slip factor reaches a slip factor threshold, updating the slip factor threshold; and reducing the braking torque so that the actual slip factor is less than the updated slip factor threshold; The determining the actual slip factor based on the braking torque and the rotational speed includes: calculate If η ₁ >η _slip , and ω<ω _min , then η=1; If η ₁ ≤ η _slip , then η = η ₁ ; Wherein, η is the actual slip factor, η _slip is the slip factor threshold, J is the moment of inertia of the aircraft wheel, ω is the rotational speed of the aircraft wheel, ω _min is a preset rotational speed threshold, and M _b is the braking torque. 2. The method according to claim 1, wherein if the actual slip factor reaches a slip factor threshold, updating the slip factor threshold comprises: If the actual slip factor is greater than or equal to a slip factor threshold, updating the peak coupling force based on the braking torque and the rotational speed; and The slip factor threshold is updated based on the updated peak binding force. 3. The method according to claim 2, wherein updating the peak value of the combined force based on the braking torque and the rotational speed comprises: pass to update the peak binding force; Among them, F _lm is the bonding force, r is the radius of the aircraft wheel; The binding force F _lm when the actual slip factor is equal to the slip factor threshold is the binding force peak value F _slip . 4. The method according to claim 3, wherein updating the slip factor threshold based on the peak binding force comprises: $\frac{{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; \&eta;</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; =</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}{<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; )</span>}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 3</span>}}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; l</span>}\mathrm{<span\; class="notranslate">\; i</span>}\mathrm{<span\; class="notranslate">\; p</span>}}}{{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; the\; s</span>}\mathrm{<span\; class="notranslate">\; the\; s</span>}}}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; k</span>}}_{\mathrm{<span\; class="notranslate">\; 4</span>}}<span\; class="notranslate">\; ;</span>$ Among them, η _ss is the preset initial value of the slip factor, F _ss is the preset initial value of the binding force, η _slip is the updated slip factor threshold, k ₁ , k ₂ , k ₃ , k ₄ is the preset coefficient, and it satisfies: -1<k ₁ <0; 0<k ₂ <1; -1<k ₃ <0; 0<k ₄ <1. 5. The method according to claim 4, further comprising: Determining the binding force F _lm based on the braking torque and the rotational speed and judging whether the binding force F _lm satisfies F _lm <k _ad F _slip ; If so, then increase the braking torque; Wherein, k _ad is the adhesion coefficient, and satisfies 0.5<k _ad <1. 6. The method according to any one of claims 3-5, further comprising: Judging whether the difference △F _slip between the peak values of the binding force after two adjacent updates is within the preset value range; If not, based on to update the peak binding force, and update the slip factor threshold based on the updated peak binding force.