Linear drive variable load control method based on push rod motor torque control

Abstract

The application discloses a variable load control method for a linear driver based on a push rod motor torque, and comprises the following steps: obtaining a current overturning angle θ of a machine cover; calculating a machine cover gravity torque M g ; calculating a push rod motor torque M p according to an acceleration requirement of the machine cover; calculating a push rod output force F p according to the push rod motor torque; judging whether the machine cover angle exceeds 90°, and determining a push rod output direction according to a judgment result: when 0°≤θ≤90°, a positive push force is output, and when 90°

Description

Technical Field

[0001] This invention relates to a control method for a linear DC motor driver, and more particularly to a variable load adaptive control method for controlling the opening and closing of the engine hood in engineering machinery and agricultural machinery. Background Technology

[0002] Construction machinery and agricultural machinery are widely used in my country's construction industry, and the maintenance and repair of their engines often require frequent opening of the engine hood. Currently, most construction machinery, such as loaders and road rollers, uses an integral tilting engine hood, characterized by a hinged connection between the front of the hood and the chassis. Opening the hood is typically achieved using methods such as gas springs, manual hydraulic pumps, valve-controlled hydraulic systems, and linear actuators.

[0003] Traditional gas spring methods are labor-intensive to operate, resulting in a large impact force when opening the hood and a limited opening angle. Manual hydraulic pump methods are slow to open and require significant physical exertion from maintenance personnel. Valve-controlled hydraulic systems are complex, costly, and difficult to maintain. In recent years, the use of DC linear actuators to open and close the hood has become an industry trend, but existing direct drive methods also have significant shortcomings.

[0004] Currently, most systems use a direct-drive motor to open and close the hood. During this process, the hood's center of gravity constantly changes, causing dynamic variations in the motor load and resulting in unstable speed, manifesting as sudden acceleration and deceleration, or vibration. In severe cases, this instability can damage the hood and the drive unit. Especially when the hood is closing near the starting point, gravity and inertia cause a significant impact between the hood and the frame, leading to deformation or damage to the hood.

[0005] Existing technologies generally employ fixed current control strategies, which cannot adapt to load variations at different angular positions of the engine shroud. Although some systems utilize position closed-loop control, the precise mathematical relationship between angle and required thrust is not established, hindering smooth control. Furthermore, the lack of effective acceleration and deceleration control strategies means that mechanical shock issues during startup and shutdown remain unresolved.

[0006] Therefore, there is an urgent need to develop an adaptive control method based on the torque control of a push rod motor, which can achieve stable control and safety protection of the machine cover under load change conditions through real-time feedback from an angle sensor and dynamic torque adjustment. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and provide a variable load control method based on a linear actuator with torque control of a push rod motor. By establishing a precise mathematical relationship model between the hood flipping angle and the driving force, and combining real-time feedback from the angle sensor, the push rod output force is dynamically adjusted to achieve smooth opening and closing of the hood and safe protection under load change conditions.

[0008] The control method based on rigid body dynamics model establishes the precise mathematical relationship between the hood flip angle and the required driving force. In the method, the current flip angle θ of the hood is first obtained, and then the gravity moment M g of the hood is calculated. The gravity moment is calculated by the formula , wherein m is the mass of the hood, g is the acceleration of gravity, L c is the distance from the center of gravity of the hood to the rotation center, and θ is the flip angle of the hood. The gravity moment changes with the flip angle of the hood, and is maximum at the horizontal position of the hood (θ=0°) and zero at the vertical position (θ=90°).

[0009] According to the acceleration requirement of the hood, the push rod motor torque T is calculated, wherein I is the moment of inertia of the hood relative to the rotation center, and α is the angular acceleration of the hood. The moment of inertia I can be calculated by the formula , assuming that the hood is a simplified model of a uniform flat plate.

[0010] According to the push rod motor torque, the push rod output force F is calculated, wherein L2 is the length of the push rod force arm, and β is the included angle between the push rod and the force arm. All parameters are substituted into the complete push rod output force formula: .

[0011] The method of the present application also considers the characteristics that the gravity moment is converted from the resistance moment to the driving moment after the hood passes the center line (θ=90°), and determines the output direction of the push rod according to the angle of the hood: when 0°≤θ≤90°, output positive thrust; when 90°<θ≤180°, output reverse braking force. According to the calculated push rod output force, the corresponding driving current is generated to control the linear drive to realize the smooth opening and closing of the hood.

[0012] To achieve smooth driving, the present application adopts S-curve control acceleration process. The target angular velocity of the hood in the acceleration stage is calculated by the formula , and the angular acceleration is calculated by the formula . This S-curve is more smooth at the start and end of acceleration than the traditional linear acceleration, reducing mechanical impact.

[0013] In the deceleration stage, the present application adopts a nonlinear deceleration strategy to control the angular velocity by the formula , wherein d norm is the normalized remaining distance, and n is the deceleration curve index and is greater than 1. This method realizes smooth deceleration when approaching the target position, effectively avoiding mechanical impact.

[0014] The present application also calculates the push rod length through geometric relationship:

[0015] Wherein the coordinates of the point (x3, y3) are determined by the hood angle θ: , .

[0016] At the same time, the telescopic speed of the push rod is calculated:

[0017] , realizing the precise control of the push rod movement.

[0018] The application also provides a variable load adaptive control system based on the above method, comprising an angle sensor, a controller, a linear driver and a built-in travel switch. The angle sensor is used to measure the turning angle θ of the hood in real time; the controller calculates the gravity moment and the push rod motor torque according to the input of the angle sensor, and calculates the required push rod output force; the linear driver controls the push rod to output the corresponding force according to the driving signal output by the controller; the built-in travel switch triggers the stop when the hood reaches the limit position, serving as the secondary protection of the angle sensor.

[0019] By using the control method of the application, the driving motor current can be automatically adjusted according to the change of the required push (pull) force at different positions during the turning of the hood, so as to avoid the phenomenon of fast and slow movement and shaking instability; when the hood falls close to the starting point, the speed control is realized to avoid the damage of the hood caused by the overpulling of the driver; the starting point and the ending point of the hood are arbitrarily set by the angle sensor, which is convenient and flexible (the linear driver is provided with a travel switch, which serves as the secondary protection). The device can automatically adjust the driving current according to the size and direction change of the load, and the opening and closing of the hood are more stable and reliable. Compared with other types of hood opening and closing devices, the structure is simple and the operation is convenient, which not only greatly reduces the labor intensity of the workers, but also improves the work efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 is the connection relationship between the hood and the linear driver of the application;

[0021] Figure 2 is the force analysis diagram of the movement process of the hood in the embodiment of the application;

[0022] Figure 3 is the hood turning state diagram when 0°≤θ≤90° in the application;

[0023] Figure 4 is the hood state diagram when θ=90° in the application;

[0024] Figure 5 is the hood turning state diagram when 90°<θ≤180° in the application;

[0025] Figure 6 is the flow structure diagram of the application.

[0026] Reference signs: 1, hood; 2, linear actuator; 3, controller ECU; 4, angle sensor. DETAILED DESCRIPTION

[0027] The application will be further described in conjunction with the accompanying drawings and specific embodiments.

[0028] As shown in Figure 1 , Figure 2 , the linear actuator variable load adaptive control system based on the force torque control of push rod motor provided by the application includes an engine hood 1, a linear actuator 2, a controller ECU 3, an angle sensor 4, and a travel switch built in the linear actuator (not shown in the figure). The hood 1 is connected with the vehicle frame through a hinge point O1, the telescopic rod of the linear actuator 3 is connected with the hood 1 through a pin shaft at the connection point O3, and the base of the linear actuator 3 is connected with the vehicle frame through a pin shaft at the connection point O2. The controller ECU 3 receives the hood overturning angle θ measured by the angle sensor 4 and outputs a control signal to the linear actuator 3.

[0029] As shown in Figure 6 , , the control method of the application is based on the rigid body dynamics model to establish the accurate mathematical relationship between the hood overturning angle and the required driving force. The rotation of the hood follows the basic equation of rigid body rotation dynamics: , where ∑M is the total torque acting on the hood, I is the moment of inertia of the hood relative to the rotation center O1, and α is the angular acceleration of the hood. The hood is jointly acted on by the push rod motor torque M p and the gravity torque M g during rotation: , therefore the required push rod motor torque can be expressed as: .

[0030] The moment of inertia I of the hood is related to the mass distribution of the hood. Assuming that the hood is a uniform flat plate, its moment of inertia can be approximated as: , where m is the mass of the hood, L c is the distance from the center of gravity of the hood to the rotation center O1. In practical applications, a more accurate moment of inertia value can be obtained through experimental measurement.

[0031] The gravity torque M g changes with the change of the hood overturning angle θ: , where g is the acceleration of gravity, θ is the overturning angle of the hood, and cos(θ) describes the component of gravity in the direction perpendicular to the force arm. This formula shows that the gravity torque is maximum when the hood is in the horizontal position (θ=0°) and zero when the hood is in the vertical position (θ=90°). When the hood angle exceeds 90°, cos(θ) becomes negative, and the gravity torque becomes a driving torque rather than a resistance torque.

[0032] The output force F pThere is a relationship between the push rod motor torque M p , where L2 is the push rod arm length, and β is the angle between the push rod and the arm. The push rod output force is solved as: . Substitute the push rod motor torque formula, and get the complete push rod output force formula: . This formula is the core of the invention, indicating that the push rod output force needs to be dynamically adjusted with the angle of the random cover.

[0033] To achieve smooth driving, the invention uses an S-curve to control the acceleration process. The target angular velocity of the machine cover in the acceleration stage is calculated by the formula , where ω max is the target constant angular velocity, t acc is the time required to complete acceleration, t is the current time and 0≤t≤t acc . The angular acceleration α(t) is the derivative of the angular velocity with respect to time, which can be calculated by the formula . This S-curve is more smooth at the start and end of acceleration compared to the traditional linear acceleration curve, reducing mechanical impact.

[0034] The invention takes into account the characteristics of the machine cover passing through the center line (as shown in Figure 4 , θ=90°) after which the gravitational torque changes from resistance torque to driving torque, and adopts a phased control strategy. When the machine cover angle is in the range of 0°≤θ≤90° (resistance stage), the push rod outputs positive thrust; when the machine cover angle is in the range of 90°<θ≤180° (driving force stage), the push rod needs to provide reverse braking force. This control strategy can be expressed as:

[0035] As shown in Figure 3 , , when 0°≤θ≤90° (resistance stage);

[0036] As shown in Figure 5 , , when 90°<θ≤180° (driving force stage).

[0037] In the deceleration stage, the invention adopts a nonlinear deceleration strategy. When the machine cover approaches the target position, calculate the normalized remaining distance , where θ remain is the remaining angle, and θ threshold is the deceleration trigger angle threshold. Then apply the nonlinear deceleration function to control the angular velocity: , where n is the deceleration curve index and n>1. A larger n value provides a smoother deceleration process, typically in the range of 1.5-3.0. This method achieves smooth deceleration when approaching the target position, effectively avoiding mechanical impact.

[0038] The invention also calculates the push rod length and speed through geometric relationships. The push rod length​ where the coordinates of point (x3, y3) are determined by the angle of the cover θ: , (x1, y1) is the coordinate of the rotation center O1 of the cover, (x2, y2) is the coordinate of the fixed end O2 of the push rod, and L1 is the distance from the rotation center O1 to the connecting point O3 of the push rod. The extension speed of the push rod is where ω is the current angular velocity of the cover. This speed calculation formula realizes the mapping relationship between the angular velocity of the cover and the linear velocity of the push rod, and ensures that the movement of the push rod is synchronized with the rotation of the cover.

[0039] The control process of the application includes four stages of initialization, acceleration, uniform speed running and deceleration. In the initialization stage, mechanical parameters (m, L c , I), geometric parameters (L1, L2) and control parameters (ω max , t acc , n) are set, the angle sensor is calibrated, the starting point angle θmin and the end point angle θ max are determined, and the state of the driver is checked. In the acceleration stage, the start / stop instruction is received, the current cover angle θ current is read, the target angular velocity and angular acceleration are calculated according to the S-shaped acceleration curve, the gravity torque, the push rod motor torque and the push rod output force are calculated, and the driving current is output. In the uniform speed running stage, the current angle θ current is read, the remaining angle θ remain is calculated, it is judged whether to enter the deceleration stage, the gravity torque is calculated, it is judged whether to pass the middle line position, the push rod output force is calculated, and the driving current is output. In the deceleration stage, the normalized remaining distance d norm is calculated, the angular velocity is reduced by applying a nonlinear deceleration function, the required push rod force is recalculated, the driving current is output, and the driving is stopped when the target position is approached.

[0040] During the entire control process, the system continuously monitors the angle anomaly, current overload and travel switch state to realize multiple safety protection. When the angle exceeds the preset range, the stop is triggered; when the current exceeds the safety threshold for a certain period of time, the protection is triggered; when the travel switch is triggered, the driving is immediately stopped.

[0041] The control system of the application includes an angle sensor 4, a controller ECU 3, a linear driver 3 and a built-in travel switch. The angle sensor 4 can adopt a potentiometer, a Hall sensor or an encoder, etc., is installed at the hinge of the cover, measures the turning angle θ of the cover in real time and outputs to the controller ECU 3. The controller ECU 3 is built-in with a microprocessor and a current driving circuit, executes the above control method according to the input of the angle sensor, calculates the gravity torque and the push rod motor torque, and outputs the driving current according to the formula The required push rod output force is calculated, and then converted into a corresponding drive current to control the linear driver 3. The linear driver 3 includes a motor and a telescopic rod, which controls the push rod to output a corresponding force according to the drive signal output by the controller, so as to realize the stable opening and closing of the machine cover. The built-in travel switch 6 is arranged in the linear driver, which triggers the stop when the machine cover reaches the limit position, serving as the secondary protection of the angle sensor.

[0042] According to the control method of the present application, the drive motor current can be automatically adjusted according to the change of the required push (pull) force at different positions during the turning of the machine cover, so as to avoid the phenomenon of fast and slow movement speed and shaking instability. When the machine cover falls close to the starting point, the speed control is realized to avoid damage caused by over-pulling of the machine cover by the driver. The starting point and the end point of the machine cover are arbitrarily set by the angle sensor, which is convenient and flexible. The device can automatically adjust the drive current according to the size and direction change of the load, so that the opening and closing of the machine cover is more stable and reliable. Compared with other types of machine cover opening and closing devices, the structure is simple and the operation is convenient, which not only greatly reduces the labor intensity of the workers, but also improves the work efficiency.

[0043] In order to better understand the present application, the present application provides a calculation example of the variable load control method based on the push rod motor torque control linear driver, which is as follows:

[0044] Initial parameter setting

[0045] This example is based on the actual parameters of a certain type of loader machine cover for method verification calculation, and the related parameters are as follows:

[0046] The mass of the machine cover m = 80 kg;

[0047] The distance L from the center of gravity to the rotation center c = 0.6 m;

[0048] The moment of inertia I = m·L c 2 = 80 × 0.6 2 = 28.8 kg·m 2 ;

[0049] The length of the push rod arm L2 = 0.3 m;

[0050] The acceleration time t acc = 2 s;

[0051] The target constant speed angular velocity ω max = 0.2 rad / s;

[0052] The deceleration curve index n = 2.0;

[0053] The deceleration trigger angle threshold θ threshold = 15°;

[0054] The gravitational acceleration g = 9.8 m / s2 ;

[0055] Geometric parameter settings:

[0056] The coordinates of the rotation center of the hood are O1(x1,y1)=(0,0)m;

[0057] The coordinates of the fixed end of the push rod are O2(x2,y2)=(0.2,-0.3)m;

[0058] The distance from the center of rotation to the push rod connection point is L1 = 0.5m;

[0059] The initial angle α between the push rod and the lever arm is 60°;

[0060] The target opening angle of the shroud is set to θ. max =110°, and the initial closed state angle is θmin=0°.

[0061] The calculation process is as follows:

[0062] 1. Acceleration phase calculation (t=0s to t=2s)

[0063] Detailed calculations were performed at four time points (t=0s, t=0.5s, t=1s, t=2s) to demonstrate the dynamic changes during the acceleration phase.

[0064] Calculation at t=0s

[0065] First, obtain the current rotation angle of the hood, θ(0) = 0°. Calculate the gravitational torque: M g =m·g·L c ·cos(θ)=80×9.8×0.6×cos(0°)=80×9.8×0.6×1=470.4N·m.

[0066] Calculate the target angular velocity using the S-shaped acceleration curve:

[0067] ω(0)=ω max ·(3·(0 / t acc ) 2 -2·(0 / t acc ) 3 = 0.2 × (3 × 0 - 2 × 0) = 0 rad / s

[0068] Calculate angular acceleration:

[0069] α(0)=(6·ω max / t acc 2 )·(0 / t acc -0 2 / t acc 2)= (6 x 0.2 / 4) x 0 = 0 rad / s 2

[0070] Calculate the force torque of the push rod motor: M p = I · a - M g = 28.8 x 0 - 470.4 = -470.4 N·m (negative sign indicates that the gravity generates resistance torque, and the push rod needs to provide positive direction torque to resist)

[0071] Calculate the output force of the push rod:

[0072] F p = M p / (L2·sin(β)) = -470.4 / (0.3 x sin(60°)) = -470.4 / (0.3 x 0.866) = -1810.6 N

[0073] Since the hood angle θ = 0° < 90° at this time, it is in the resistance stage, and the push rod needs to provide a positive thrust, so the actual thrust value is 1810.6 N.

[0074] Calculate the coordinates of the push rod connection point:

[0075] x3 = x1 + L1·sin(θ) = 0 + 0.5 x sin(0°) = 0 m y3 = y1 - L1·cos(θ) = 0 - 0.5 x cos(0°) = -0.5 m

[0076] Calculate the current length of the push rod: L p = √((x3 - x2) 2 + (y3 - y2) 2 )= √((0 - 0.2) 2 + (-0.5 - (-0.3)) 2 )= √(0.04 + 0.04) = √0.08 = 0.283 m

[0077] The push rod extension speed is 0 at this time, because the initial state angular velocity is 0.

[0078] t = 0.5 s calculation

[0079] Apply S-shaped acceleration curve to calculate the target angular velocity: ω(0.5) = ω max · (3·(0.5 / 2) 2 - 2·(0.5 / 2) 3 )= 0.2 x (3 x 0.0625 - 2 x 0.015625) = 0.2 x (0.1875 - 0.03125) = 0.2 x 0.15625 = 0.03125 rad / s

[0080] Calculate the angular acceleration:

[0081] α(0.5)=(6·ω max / t acc 2 )·(0.5 / t acc -(0.5) 2 / t acc 2 )=(6×0.2 / 4)·(0.25-0.0625)=0.3×0.1875=0.05625rad / s 2

[0082] Estimate the current angle (approximate by integration):

[0083] θ(0.5)≈θ(0)+ω(0)×0.5+0.5×α(0)×0.5 2 ≈0+0×0.5+0.5×0×0.25≈0° (In the initial acceleration state, the angle change is very small, so it is simplified to 0 here)

[0084] Calculate the gravitational torque: M g =80×9.8×0.6×cos(0°)=470.4N·m

[0085] Calculate the torque of the push rod motor:

[0086] M p =28.8×0.05625-470.4=1.62-470.4=-468.78N·m

[0087] Calculate the output force of the push rod:

[0088] F p =-468.78 / (0.3×sin(60°))=-468.78 / (0.3×0.866)=-1804.25N

[0089] Since the hood angle θ≈0°<90° at this time, it is in the resistance stage, and the push rod needs to provide positive thrust. Therefore, the actual thrust value is 1804.25N.

[0090] Calculation at t=1s

[0091] Calculate the target angular velocity using the S-shaped acceleration curve:

[0092] ω(1)=0.2×(3×(1 / 2) 2 -2×(1 / 2) 3 )=0.2×(3×0.25-2×0.125)=0.2×(0.75-0.25)=0.2×0.5=0.1rad / s

[0093] Calculate angular acceleration:

[0094] a(1) = (6 x 0.2 / 4) x (1 / 2 - (1) 2 / 4) = 0.3 x (0.5 - 0.25) = 0.3 x 0.25 = 0.075 rad / s 2

[0095] Estimate current angle (approximated by integration):

[0096] theta(1) = theta(0) + integral from 0 to t of omega(t) dt 1 = 0 + 0.05 = 2.86° (estimated value using average angular velocity 0.05 rad / s)

[0097] Calculate gravitational torque:

[0098] M g = 80 x 9.8 x 0.6 x cos(2.86°) = 80 x 9.8 x 0.6 x 0.9988 = 469.8 N·m

[0099] Calculate push rod motor torque:

[0100] M p = 28.8 x 0.075 - 469.8 = 2.16 - 469.8 = -467.64 N·m

[0101] Calculate push rod output force:

[0102] F p = -467.64 / (0.3 x sin(60°)) = -467.64 / (0.3 x 0.866) = -1799.5 N

[0103] Since the hood angle θ = 2.86° < 90° at this time, it is in the resistance stage, and the push rod needs to provide a positive thrust, so the actual thrust value is 1799.5 N.

[0104] Calculation at t = 2 s (acceleration end point)

[0105] Apply S-shaped acceleration curve to calculate target angular velocity:

[0106] omega(2) = 0.2 x (3 x (2 / 2) 2 - 2 x (2 / 2) 3 ) = 0.2 x (3 x 1 - 2 x 1) = 0.2 x 1 = 0.2 rad / s

[0107] Calculate angular acceleration:

[0108] a(2) = (6 x 0.2 / 4) x (2 / 2 - (2) 2 / 4) = 0.3 x (1 - 1) = 0 rad / s 2(Angular acceleration of the end of acceleration is 0)

[0109] Estimate current angle (approximated by integration):

[0110] θ(2)≈θ(0)+∫ 2 ω(t)dt≈0+0.2≈11.46°(estimated value using average angular velocity 0.1 rad / s)

[0111] Calculate the gravity moment:

[0112] M g =80×9.8×0.6×cos(11.46°)=80×9.8×0.6×0.98=461.1N·m

[0113] Calculate the push rod motor torque: M p =28.8×0-461.1=-461.1N·m

[0114] Calculate the push rod output force:

[0115] F p =-461.1 / (0.3×sin(60°))=-461.1 / (0.3×0.866)=-1775.3N

[0116] Since the hood angle θ=11.46°<90° at this time, it is in the resistance stage, and the push rod needs to provide a positive thrust, so the actual thrust value is 1775.3N.

[0117] 2. Uniform speed running stage calculation

[0118] Select three angle positions (θ=30°, θ=60°, θ=90°) for calculation, and show the thrust adjustment of the uniform speed stage with angle change.

[0119] Calculation when θ=30°

[0120] In the uniform speed stage, the angular velocity remains a constant value ω=0.2 rad / s, and the angular acceleration α=0 rad / s 2 .

[0121] Calculate the gravity moment:

[0122] M g =80×9.8×0.6×cos(30°)=80×9.8×0.6×0.866=407.5N·m

[0123] Calculate the push rod motor torque: M p =28.8×0-407.5=-407.5N·m

[0124] Calculate the push rod output force:

[0125] F p =-407.5 / (0.3×sin(60°))=-407.5 / (0.3×0.866)=-1568.2N

[0126] Since the angle of the fairing θ = 30° < 90° at this time, it is in the resistance stage, and the push rod needs to provide a positive thrust, so the actual thrust value is 1568.2N.

[0127] Calculate the coordinates of the push rod connection point:

[0128] x3 = 0 + 0.5 × sin(30°) = 0 + 0.5 × 0.5 = 0.25m y3 = 0 - 0.5 × cos(30°) = 0 - 0.5 × 0.866 = -0.433m

[0129] Calculate the current length of the push rod:

[0130] L p =√((0.25-0.2) 2 +(-0.433-(-0.3)) 2 )=√(0.0025+0.01773)=√0.02023=0.142m

[0131] Calculate the push rod extension speed:

[0132] v p =0.2×(1 / 0.142)×[(0.25-0.2)(0.5×cos(30°))+((-0.433)-(-0.3))(0.5×sin(30°))]=0.2×7.04×[0.05×0.433+(-0.133)×0.25]=1.41×[0.02165-0.03325]=1.41×(-0.0116)=-0.0164m / s(negative value indicates push rod contraction)

[0133] θ = 60° calculation

[0134] Calculate the moment of gravity:

[0135] M g =80×9.8×0.6×cos(60°)=80×9.8×0.6×0.5=235.2N·m

[0136] Calculate the push rod motor torque: M p =28.8×0-235.2=-235.2N·m

[0137] Calculate the push rod output force:

[0138] F p= -235.2 / (0.3 x sin(60°)) = -235.2 / (0.3 x 0.866) = -905.1 N

[0139] Since the angle of the housing at this time θ = 60° < 90°, it is in the resistance stage, and the push rod needs to provide a positive thrust, so the actual thrust value is 905.1 N.

[0140] Calculate the coordinates of the push rod connection point:

[0141] x3 = 0 + 0.5 x sin(60°) = 0 + 0.5 x 0.866 = 0.433 m y3 = 0 - 0.5 x cos(60°) = 0 - 0.5 x 0.5 = -0.25 m

[0142] Calculate the current length of the push rod:

[0143] L p = √((0.433 - 0.2) 2 + (-0.25 - (-0.3)) 2 )= √(0.05429 + 0.0025) = √0.05679 = 0.238 m

[0144] Calculate the push rod extension speed:

[0145] v p = 0.2 x (1 / 0.238) x [(0.433 - 0.2) (0.5 x cos(60°)) + ((-0.25) - (-0.3)) (0.5 x sin(60°))] = 0.2 x 4.2 x [0.233 x 0.25 + 0.05 x 0.866] = 0.84 x [0.05825 + 0.0433] = 0.84 x 0.10155 = 0.0853 m / s (positive value indicates push rod extension)

[0146] Calculation at θ = 90°

[0147] Calculate the gravity moment:

[0148] M g = 80 x 9.8 x 0.6 x cos(90°) = 80 x 9.8 x 0.6 x 0 = 0 N·m (the gravity moment at 90° position is zero)

[0149] Calculate the push rod motor torque: M p = 28.8 x 0 - 0 = 0 N·m

[0150] Calculate the push rod output force:

[0151] F p = 0 / (0.3 x sin(60°)) = 0 / (0.3 x 0.866) = 0 N (no thrust is needed at 90° position)

[0152] Calculate the push rod connection point coordinates:

[0153] x3=0+0.5×sin(90°)=0+0.5×1=0.5m y3=0-0.5×cos(90°)=0-0.5×0=0m

[0154] Calculate the current length of the push rod:

[0155] L p =√((0.5-0.2) 2 +(0-(-0.3)) 2 )=√(0.09+0.09)=√0.18=0.424m

[0156] Calculate the push rod extension speed:

[0157] v p =0.2×(1 / 0.424)×[(0.5-0.2)(0.5×cos(90°))+(0-(-0.3))(0.5×sin(90°))]=0.2×2.358×[0.3×0+0.3×1]=0.472×0.3=0.142m / s(positive value indicates push rod extension)

[0158] 3. Calculate after crossing the center line phase (θ=100°)

[0159] After the hood angle exceeds 90°, the gravity moment is converted from the resistance moment to the driving moment, and the push rod needs to provide a reverse braking force.

[0160] Calculate the gravity moment:

[0161] M g =80×9.8×0.6×cos(100°)=80×9.8×0.6×(-0.1736)=-81.7N·m(negative sign indicates that the gravity generates a driving moment)

[0162] Calculate the push rod motor moment: M p =28.8×0-(-81.7)=81.7N·m(positive sign indicates that the push rod needs to provide a resistance moment)

[0163] Calculate the push rod output force:

[0164] F p =81.7 / (0.3×sin(60°))=81.7 / (0.3×0.866)=314.5N

[0165] Since the hood angle θ=100°>90° at this time, it is in the driving force stage, and the push rod needs to provide a reverse braking force, so the output braking force is 314.5N.

[0166] 4. Calculation of deceleration phase

[0167] Assuming the shroud is 100° close to the target position, and there is still 10° of angle remaining to reach the target position θ. max =110°.

[0168] Calculate the remaining angle: θ remain =|θ max -θ current |=|110°-100°|=10°

[0169] Due to θ remain <θ threshold (15°), entering the deceleration phase.

[0170] Calculate the standardized residual distance: d norm =θ remain / θ threshold =10 / 15=0.667

[0171] Calculate the target angular velocity using a nonlinear deceleration function: ω = ω max ·(d norm ) n =0.2×(0.667) 2 =0.2 × 0.445 = 0.089 rad / s (angular velocity decreases to 44.5% of the constant velocity state)

[0172] Calculate the required angular deceleration (assuming a deceleration from 0.2 rad / s to 0.089 rad / s within 2 seconds): α = (0.089 - 0.2) / 2 = -0.0555 rad / s 2

[0173] Calculate the gravitational torque: M g =80×9.8×0.6×cos(100°)=-81.7N·m

[0174] Calculate the torque of the push rod motor:

[0175] M p =28.8×(-0.0555)-(-81.7)=-1.6+81.7=80.1N·m

[0176] Calculate the output force of the push rod:

[0177] F p =80.1 / (0.3×sin(60°))=80.1 / (0.3×0.866)=308.3N

[0178] Since the bonnet angle θ = 100° > 90° at this time, it is in the driving force stage, and the push rod needs to provide a reverse braking force, so the output braking force is 308.3N.

[0179] 5. Calculation of the position near the stop (θ = 108°)

[0180] When the bonnet approaches the end position (θ = 108°), the remaining angle is only 2°.

[0181] Calculate the normalized remaining distance: d norm = 2 / 15 = 0.133

[0182] Apply the nonlinear deceleration function to calculate the target angular velocity:

[0183] ω = 0.2 × (0.133) 2 = 0.2 × 0.0177 = 0.0035 rad / s (angular velocity reduced to 1.77% of uniform speed)

[0184] Calculate the gravitational torque:

[0185] M g = 80 × 9.8 × 0.6 × cos(108°) = 80 × 9.8 × 0.6 × (-0.309) = -145.5 N·m

[0186] Calculate the required angular deceleration (at this time, it is close to stopping): α ≈ -0.01 rad / s 2

[0187] Calculate the push rod motor torque:

[0188] M p = 28.8 × (-0.01) - (-145.5) = -0.288 + 145.5 = 145.2 N·m

[0189] Calculate the push rod output force:

[0190] F p = 145.2 / (0.3 × sin(60°)) = 145.2 / (0.3 × 0.866) = 559.0 N

[0191] Since the bonnet angle θ = 108° > 90° at this time, it is in the driving force stage, and the push rod needs to provide a reverse braking force, so the output braking force is 559.0N.

[0192] Result analysis

[0193] Through the above detailed calculation, the following conclusions are drawn:

[0194] Acceleration phase characteristics: The push rod force gradually decreases from the initial 1810.6N to 1775.3N, because as the hood angle increases, the gravity moment decreases, and the resistance required to be overcome also decreases. The S-shaped acceleration curve achieves a smooth start, the angular acceleration starts from 0, the maximum value appears in the middle (t=1s), and then returns to 0, avoiding sudden impact.

[0195] Constant speed phase characteristics: The push rod force decreases significantly as the hood angle increases: 1568.2N is required at 30°, 905.1N at 60°, and no push force is required at 90°.

[0196] The extension and retraction speed of the push rod changes from negative (-0.0164m / s at θ=30°) to positive (0.0853m / s at θ=60°), indicating that the push rod first retracts and then extends, which is consistent with the geometric relationship of the hood movement.

[0197] After the midline characteristics: When the hood angle exceeds 90°, the gravity moment changes from resistance to driving force, and the push rod needs to change from providing thrust to providing braking force.

[0198] At θ=100°, a braking force of 314.5N is required to prevent the hood from moving too fast under the action of gravity.

[0199] Deceleration phase characteristics: The braking force increases from 308.3N to 559.0N during the deceleration phase, because as the hood approaches the end point, a larger braking force is required to stop it smoothly.

[0200] Non-linear deceleration strategy (n=2) makes the speed decay in a square relationship with the remaining distance, providing a smooth speed transition.

[0201] System adaptability: Throughout the process, the push rod force is dynamically adjusted according to the hood angle, angular velocity and angular acceleration, adapting to load changes.

[0202] When the hood opens from 0° to 110°, the change range of the push rod force reaches 1810.6N to 559.0N, indicating that the fixed current driving mode cannot meet the demand.

[0203] Through the implementation of this method, the hood can maintain a smooth movement state throughout the opening and closing process, avoiding sudden speed changes and shaking phenomena, especially when approaching the end point position, effectively avoiding mechanical impact through the non-linear deceleration strategy. At the same time, the system can automatically adjust the push rod output force according to different angle positions, realizing variable load adaptive control.

Claims

1. A linear drive variable load control method based on push rod motor torque control, characterized in that, Comprising: Acquire the current angle of the hood θ; Moment of gravity M of the computer cover g , which is calculated by the following formula: , wherein m is the mass of the cover, g is the acceleration of gravity, L c is the distance from the center of gravity of the cover to the rotation center, and θ is the turning angle of the cover. According to the acceleration requirement of the machine cover, the push rod motor torque M is calculated p : , wherein I is the moment of inertia of the machine cover relative to the rotation center, and a is the angular acceleration of the machine cover. According to the force arm length of the putter, the putter output force F is calculated p : , wherein L2 is the force arm length of the putter, and β is the included angle between the putter and the force arm. Substitute the complete formula into the output force of the push rod: ; Determine whether the angle of the hood exceeds 90°, and determine the output direction of the push rod according to the result: when 0°≤θ≤90°, output positive thrust, when 90°<θ≤180°, output reverse braking force; According to the output force of the push rod, generate the corresponding drive current to control the linear driver, and realize the smooth opening and closing of the hood.

2. The push rod motor torque control linear drive variable load control method of claim 1, wherein, The moment of inertia I of the hood is calculated by the following equation: where m is the mass of the hood, L c is the distance from the center of rotation to the center of mass of the hood.

3. The push rod motor torque control linear driver variable load control method according to claim 1, wherein, Also comprising: According to the current angle θ of the hood, the push rod length L is calculated p : , wherein the coordinates of x3, y3 are determined by the hood angle θ: , ; x1, y1 are the coordinates of the hood rotation center; x2, y2 are the coordinates of the fixed end of the push rod, and L1 is the distance from the rotation center to the push rod connection point.

4. The push rod motor torque control linear drive variable load control method according to claim 3, wherein, Also comprising: The telescopic speed v of the pushrod is calculated p : where ω is the current angular speed of the cowling, L p is the current length of the pushrod.

5. The push-rod motor torque control linear drive variable load control method of claim 1, wherein, The target angular velocity ω(t) of the hood in the acceleration phase is calculated by a sigmoid curve: where ω max is the target constant angular velocity, t acc is the time needed to complete the acceleration, and t is the current time.

6. The push-rod motor torque control linear drive variable load control method of claim 1, wherein, The target angular velocity ω of the hood in the deceleration phase is calculated by the following equation: where ω max is the angular velocity when running at constant speed, d norm is the normalized remaining distance, d norm = θ remain / θ threshold , θ remain is the remaining angle, θ threshold is the deceleration trigger angle threshold, and n is the deceleration curve exponent and n > 1.

7. Linear drive variable load adaptive control system based on the method according to any one of claims 1 to 6, characterized in that Comprising: Angle sensor for real-time measurement of the turning angle of the hood θ; a controller for calculating the gravity moment from the input of the angle sensor and the force moment of the push rod motor and calculating the required push rod output force from the formula ​ Linear driver, including motor and telescopic rod, controls the push rod to output corresponding force according to the drive signal output by the controller, realizes the smooth opening and closing of the hood; Built-in travel switch is set in the linear driver, which triggers stop when the hood reaches the limit position, serving as secondary protection for the angle sensor.

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