Ramp braking compensation control method for electric transmission bulldozer

Abstract

The invention discloses a ramp braking compensation control method for an electric transmission bulldozer, which is characterized in that a certain torque is increased or reduced on the basis of original PID (Proportion Integration Differentiation) control output so as to counteract the gravity influence caused by the gradient, so that a control system is still designed to adjust the speed according to the level road. By compensating the torque, the whole vehicle can run on a flat ground under different slopes, the driving experience and the control precision are improved, and the situation that the vehicle is difficult to start on a slope or overspeed and out-of-control during downhill is prevented.

Description

Technical Field

[0001] This invention relates to the field of bulldozer control, and more particularly to a slope braking compensation control method for an electric drive bulldozer. Background Technology

[0002] In uneven terrain, due to the heavy weight of bulldozers (approximately 50 tons), changes in slope can lead to the following situations: when going uphill, the gravitational component tends to slide downhill, resulting in insufficient driving torque and a drop in vehicle speed; when going downhill, the force component propels the entire vehicle to accelerate, but the PID output is insufficient for braking, leading to loss of vehicle speed control.

[0003] Therefore, it is necessary to develop new control methods to improve the stability of bulldozers when going uphill or downhill. Summary of the Invention

[0004] Purpose of the invention: To address the shortcomings and defects of existing technologies, this invention provides a slope braking compensation control method for electric drive bulldozers. By compensating for torque, the entire vehicle can "perform as if driving on flat ground under different slopes," improving the driving experience and control precision, and preventing difficulties in starting on slopes or loss of control due to excessive speed on downhill slopes.

[0005] Technical solution: The present invention provides a slope braking compensation control method for an electric drive bulldozer, characterized by the following steps:

[0006] 1) Input the bulldozer's pitch angle θ through the vehicle attitude sensor, with the longitudinal direction of the vehicle body as a reference. Positive values ​​indicate uphill, and negative values ​​indicate downhill.

[0007] 2) Calculate the gravitational component Fslope=m×g×sin(θ) in the slope direction of the bulldozer, where m is the mass of the whole vehicle, g is the gravitational acceleration, and θ is the pitch angle;

[0008] 3) Convert the gravity component into torque Tslope=ηFslope×r / η=m×g×sin(θ)×r / η, where r is the track radius or equivalent transmission radius, and η is the transmission efficiency; so as to convert it into motor control quantity;

[0009] 4) The compensation torque calibration adopts theoretical initial value calculation + actual vehicle fine-tuning; the theoretical initial value calculation adopts theoretical modeling, sets different slope angles to calculate the weight component of the bulldozer and the required compensation torque, and establishes a table. The actual torque is based on the track radius and transmission efficiency; the actual vehicle fine-tuning adopts actual vehicle data acquisition, straight-line test at different slopes, records the speed drop / overspeed situation without compensation, the trend of PID output torque change, manually fine-tunes the compensation torque, and observes whether the vehicle speed is stable; finally, a slope-torque mapping table is formed.

[0010] 5) The control strategy adopts a fusion method. The driving torque is the PID output torque plus the compensation torque, i.e., Tcmd=TPID+Tslope; direction judgment: when going uphill, θ>0, increase positive torque; when going downhill, θ<0, decrease torque or become negative torque; complete the bulldozer slope braking compensation control.

[0011] In step 3), the transmission efficiency η varies between 0.85 and 0.95 depending on the transmission chain.

[0012] In step 4), straight-line tests are conducted at different slopes, including 5°, 10°, and 15°.

[0013] In step 4), the slope-torque mapping table is a piecewise linear table.

[0014] In step 5), dynamic smoothing is used to prevent sudden changes in the angle signal from affecting the torque, and a first-order filter or gradient limitation is added.

[0015] In step 5), compensation is ignored for slopes less than ±1° to avoid disturbances caused by sensor noise.

[0016] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: Based on the original PID control output, this invention increases or decreases a certain amount of torque to "counteract" the gravity effect caused by the slope, allowing the control system to still adjust the speed according to the "flat road" design. By compensating for torque, the vehicle "behaves as if driving on flat ground at different slopes," improving the driving experience and control precision, and preventing difficulties in starting on slopes or loss of control due to excessive speed on downhill slopes. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the present invention;

[0018] Figure 2 This is a schematic diagram of the present invention. Detailed Implementation

[0019] The technical solution of the present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0020] The slope braking compensation control method for electric drive bulldozers of the present invention includes the following steps:

[0021] 1) Input the bulldozer's pitch angle θ through the vehicle attitude sensor, with the longitudinal direction of the vehicle body as a reference. Positive values ​​indicate uphill, and negative values ​​indicate downhill.

[0022] 2) Calculate the gravitational component Fslope=m×g×sin(θ) in the slope direction of the bulldozer, where m is the mass of the whole vehicle, g is the gravitational acceleration, and θ is the pitch angle;

[0023] 3) Convert the gravitational component into torque Tslope=ηFslope×r / η=m×g×sin(θ)×r / η, where r is the track radius or equivalent transmission radius, and η is the transmission efficiency; so as to convert it into a motor control quantity; the transmission efficiency η is between 0.85 and 0.95 depending on the transmission chain.

[0024] 4) The compensation torque calibration adopts theoretical initial value calculation + actual vehicle fine-tuning; the theoretical initial value calculation adopts theoretical modeling, sets different slope angles to calculate the weight component of the bulldozer and the required compensation torque, and establishes a table. The actual torque is based on the track radius and transmission efficiency; the actual vehicle fine-tuning adopts actual vehicle data acquisition, straight-line tests are carried out at different slopes, the deceleration / overspeed situation without compensation is recorded, the trend of PID output torque change is recorded, the compensation torque is manually fine-tuned, and the vehicle speed is observed to ensure stability; finally, a slope-torque mapping table is formed; straight-line tests are carried out at different slopes, including 5°, 10°, and 15°; the slope-torque mapping table adopts a piecewise linear table;

[0025] 5) The control strategy adopts a fusion method. The driving torque is the PID output torque plus a compensation term torque, i.e., Tcmd=TPID+Tslope; direction judgment: when going uphill, θ>0, increase positive torque; when going downhill, θ<0, decrease torque or become negative torque; complete the bulldozer slope braking compensation control; adopt dynamic smoothing to prevent sudden changes in angle signal from affecting torque, and add a first-order filter or gradient limit; ignore compensation for slope less than ±1° to avoid disturbances caused by sensor noise.

[0026] Example:

[0027] As shown in the figure, this embodiment presents a slope braking compensation control method for electric drive bulldozers:

[0028] I. Sensor Input:

[0029] Pitch Angle: Measured from the vehicle's attitude sensor, in degrees or rad;

[0030] With the longitudinal direction of the vehicle body as a reference, positive values ​​represent uphill and negative values ​​represent downhill.

[0031] II. Formula for calculating gravitational components:

[0032] When the slope is θ, the gravitational component of the bulldozer in the slope direction is Fslope=m×g×sin(θ); where m is the total mass of the vehicle (kg) approximately 50,000 kg; g is the gravitational acceleration, 9.81 m / s²; and θ is the pitch angle (slope angle).

[0033] To make it easier to convert to motor control quantities, it is usually converted into torque:

[0034] Tslope = ηFslope × r / η = m × g ⋅ sin(θ) × r / η; where r is the track radius (or equivalent transmission radius), in meters; and η is the transmission efficiency (0.85-0.95, depending on the transmission chain).

[0035] III. Compensation Torque Calibration Method:

[0036] Initial values ​​were calculated theoretically, and then fine-tuned on a real vehicle.

[0037] 1. Theoretical modeling: With a fixed vehicle weight of 50 tons, different slope angles (-20° to +20°) are set; the gravity components and required compensation torque are calculated, and a table is created:

[0038] Slope (°) sin(θ) Compensating force F (N) Compensating torque T (Nm) 0° 0 0 0 +5° 0.087 42694 ≈8500 +10° 0.174 85387 ≈17000 -5° -0.087 -42694 ≈-8500 -10° -0.174 -85387 ≈-17000

[0039] The actual torque depends on the track radius and transmission efficiency, such as r=0.5m, η=0.9.

[0040] 2. Real vehicle data collection: Conduct straight-line tests on typical slopes (5°, 10°, 15°) and record: speed drop / overspeed without compensation; PID output torque change trend. Manually fine-tune the compensation torque and observe whether the vehicle speed is stable.

[0041] 3. Create a slope-torque mapping table using a piecewise linear table (Look-Up Table).

[0042] IV. Fusion Methods in Control Strategies:

[0043] 1. Add a compensation term after PID: Tcmd = TPID + Tslope.

[0044] 2. Direction determination: When going uphill, θ>0, increase positive torque; when going downhill, θ<0, decrease torque or become negative torque.

[0045] 3. Dynamic smoothing: To prevent sudden changes in angle signals from affecting torque, a first-order filter or gradient limit is added (e.g., maximum rate of change 1000 Nm / s).

[0046] 4. Slope dead zone handling: Slopes less than ±1° are ignored for compensation to avoid disturbances caused by sensor noise.

[0047] This invention adds or reduces torque based on the original PID control output to "counteract" the gravitational effects caused by the slope, allowing the control system to adjust speed as if driving on flat ground. By compensating for torque, the vehicle "behaves as if driving on flat ground at different slopes," improving the driving experience and control precision, and preventing difficulties starting on slopes or loss of control due to excessive speed on downhill slopes.

Claims

1. A method of slope brake compensation control for an electrically driven bulldozer, characterized by: The method comprises the following steps: 1) input the pitch angle θ of the bulldozer through the whole vehicle posture sensor, taking the vehicle body longitudinal direction as the reference, positive value for uphill and negative value for downhill; 2) calculate the gravity component in the slope direction of the bulldozer Fslope = m x g x sin(θ), wherein m is the whole vehicle mass, g is the gravity acceleration, and θ is the pitch angle; 3) convert the gravity component into torque Tslope = ηFslope x r / η = m x g x sin(θ) x r / η, wherein r is the track radius or equivalent transmission radius, and η is the transmission efficiency, so as to convert into the motor control quantity; 4) compensate the torque calibration by using theoretical calculation initial value + actual vehicle fine adjustment; the theoretical calculation initial value is calculated by theoretical modeling, setting different slope angles to calculate the gravity component of the bulldozer and the required compensation torque, establishing a table, and the actual torque is based on the track radius and the transmission efficiency; the actual vehicle fine adjustment is achieved by collecting actual vehicle data, doing straight running test at different slopes, recording the speed drop / speed increase without compensation, the PID output torque change trend, manually fine adjusting the compensation torque, and observing whether the vehicle speed is stable; finally, the slope-torque mapping table is formed; 5) the control strategy adopts a fusion method, the driving torque is the PID output torque plus the compensation torque, i.e. Tcmd = TPID + Tslope; the direction is judged as follows: when uphill, θ > 0, the positive torque is increased, and when downhill, θ < 0, the torque is reduced or becomes negative torque; the bulldozer slope braking compensation control is completed.

2. The electrically driven bulldozer ramp brake compensation control method of claim 1, characterized by: In step 3), the transmission efficiency η is between 0.85-0.95 according to different transmission chains.

3. The electrically driven bulldozer ramp brake compensation control method of claim 1, characterized by: In step 4), the straight running test is done at different slopes, including 5°, 10°, and 15°.

4. The electrically driven bulldozer ramp brake compensation control method of claim 1, characterized by: In step 4), the slope-torque mapping table adopts a segmented linear table.

5. The electrically driven bulldozer ramp brake compensation control method of claim 1, characterized by: In step 5), dynamic smoothing processing is adopted to prevent the torque from being affected by the angle signal mutation, and a first-order filter or gradient limit is added.

6. The electrically driven bulldozer ramp brake compensation control method of claim 1, characterized by: In step 5), the slope less than ±1° is ignored for compensation, so as to avoid the disturbance caused by sensor noise.

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