CN116101078A

CN116101078A - Automatic speed control system and method for electric mining dump truck

Info

Publication number: CN116101078A
Application number: CN202211521435.1A
Authority: CN
Inventors: 张伟康; 李怀义; 杨海; 陈文鹏
Original assignee: Jiangsu Advanced Construction Machinery Innovation Center Ltd
Current assignee: Jiangsu Advanced Construction Machinery Innovation Center Ltd
Priority date: 2022-11-30
Filing date: 2022-11-30
Publication date: 2023-05-12

Abstract

The invention discloses an automatic speed control system and method for an electric mining dump truck, wherein an expected vehicle speed is determined according to a current retarding handle gear, the current vehicle speed is calculated according to a motor rotating speed obtained in real time, and the driving torque or the braking torque is calculated through a vehicle speed closed-loop control algorithm. When the motor provides braking torque during downhill, and the required braking torque cannot be provided singly by the motor after the expected vehicle speed is exceeded, the insufficient braking torque is automatically provided by a hydraulic braking system, and speed limitation is carried out under electromechanical compound braking. The motor provides driving torque to make the vehicle stably run on a flat ground or an ascending slope. The automatic speed control system and method for the electric mining dump truck provided by the invention ensure that the electric mining dump truck runs at a stable vehicle speed when descending a slope. The vehicle can automatically perform stable speed control, and the driver operation is liberated. The oil acceleration demand or the braking demand can be responded to in real time.

Description

Automatic speed control system and method for electric mining dump truck

Technical Field

The invention relates to an automatic speed control system and method for an electric mining dump truck, and belongs to the technical field of automatic control of engineering machinery.

Background

The common operation working condition of the electric mining dump truck is long-distance continuous downhill. When the electric mining dump truck is in a downhill working condition, the electric mining dump truck basically has an electric braking function, and through different retarding gears, the motor is controlled to provide different braking torques, so that a driver is prevented from stepping on a brake pedal for a long time, and energy recovery can be performed. Currently, the calculation of the electric braking torque generally utilizes a vehicle dynamics formula, but the weight in the formula is calculated, and the weight is needed to be obtained by additionally assembling a load sensor; the coefficient of road friction resistance is more difficult to obtain accurately. Thus, the calculated electric brake torque is not necessarily accurate, resulting in difficulty in precisely performing speed limitation on a downhill slope. Moreover, when the battery is excessively charged or the motor braking torque is insufficient, the motor cannot provide the required braking torque, and at the moment, a driver is still required to actively step on the brake to perform mechanical braking, otherwise, overspeed phenomenon occurs in the vehicle.

When the vehicle is in long-distance ascending or flat ground working conditions, a driver is required to step on the accelerator pedal for a long time to drive, and stable-speed running cannot be automatically performed. In addition, on a bumpy mine pavement, the vehicle is bumpy up and down, so that a driver cannot accurately control the depth of the accelerator, and the phenomenon of fluctuation of the speed of the vehicle, which is suddenly accelerated and suddenly decelerated, is caused, and the driving experience is affected.

The first prior art is an adaptive safety speed limiting protection system of an electric transmission mining dump truck, wherein after the vehicle overspeed, a vehicle controller VCU applies electric braking of different modes according to the current motor temperature and the vehicle speed; if the current motor temperature is higher than the set temperature, the standard electric brake is applied, otherwise the maximum electric brake is applied. According to the technical scheme, the current state of the electric transmission mining dump truck can be automatically matched with the safety speed limit protection, particularly, the self-adaptive safety speed limit is carried out on vehicles under downhill working conditions, overspeed running of the vehicles is avoided, and the running safety and the transportation efficiency of the vehicles are improved. However, the first prior art brake torque calculation relies on mathematical formulas and is primarily applicable to downhill conditions.

The second prior art relates to an automatic electric creep system and method for an electric transmission mining dump truck, which can automatically judge the running condition of a vehicle and control the vehicle to automatically enter an electric creep state when the vehicle descends. When the vehicle exits the downhill, the electric creep state is automatically exited. The automatic control mode avoids tedious manual operation and reduces the labor intensity of drivers. The vehicle fault caused by insufficient driving experience of a driver is reduced, and the running efficiency and the intelligent degree of the vehicle are effectively improved. However, the second prior art focuses on the automatic switching process of the electric creep mode, mainly applied in downhill slowing, and does not consider the downhill overspeed condition.

The third prior art is a mining dump truck creep automatic control device and method, wherein a controller obtains current vehicle speed information through a speed sensor and compares the current vehicle speed information with a calculated current maximum allowable vehicle speed vmax; if the current speed of the vehicle exceeds vmax, the controller sends out a command, and the proportional control device slowly operates the wet disc brake until the speed of the vehicle is reduced to v1. The maximum speed threshold of the current vehicle is calculated in advance according to the gradient and the specified braking distance, and once the speed reaches the threshold, the controller sends out an instruction to start the creep function of the brake, so that the vehicle runs at the safe speed. However, the third prior art limits speed by mechanical braking and does not relate to the motor braking function on the electric vehicle type.

In summary, the method is mainly applied to downhill electric creep speed control in the prior art, the calculation of the electric braking torque mainly depends on a dynamics calculation formula, when parameters such as a rolling resistance coefficient, a wind resistance coefficient and the like cannot be accurately obtained, a calculation result is inaccurate, stable speed control is difficult to perform, and after overspeed, a driver is required to cooperatively step on a brake pedal to perform deceleration.

Disclosure of Invention

The purpose is as follows: in order to solve the problems that in long-distance downhill electric retarding control of an electric mining dump truck, electric braking torque calculation is inaccurate, stable speed control cannot be performed, a driver still needs to step on a brake pedal to slow down after overspeed, and long-distance flat ground or uphill cannot automatically perform stable speed driving, the invention provides an automatic speed control system and method of the electric mining dump truck. When the motor provides braking torque during downhill, and the required braking torque cannot be provided singly by the motor after the expected vehicle speed is exceeded, the insufficient braking torque is automatically provided by a hydraulic braking system, and speed limitation is carried out under electromechanical compound braking. When the vehicle is on a level ground or a downhill, the motor provides driving torque to enable the vehicle to stably run at a desired speed.

The technical scheme is as follows: in order to solve the technical problems, the invention adopts the following technical scheme:

in a first aspect, an automatic speed control system for an electric mining dump truck includes: the device comprises a retarding handle, a retarding switch, an accelerator pedal, a brake pedal, an inclination sensor, a whole vehicle controller, a motor, a gearbox, a running system, a braking proportional electromagnetic valve and a hydraulic brake.

And the retarding handle is connected with the whole vehicle controller and is used for providing different vehicle speed gears.

And the retarder switch is connected with the whole vehicle controller and is used for judging whether the automatic speed mode is started or not.

The accelerator pedal is connected with the whole vehicle controller and is used for vehicle acceleration requirements.

And the brake pedal is connected with the whole vehicle controller and is used for braking the vehicle speed.

The inclination angle sensor is connected with the whole vehicle controller and used for detecting the working condition of the current vehicle on an ascending slope, a flat ground or a descending slope.

The whole vehicle controller is used for controlling the whole vehicle to run and executing the automatic speed control method.

The motor controller is connected with the whole vehicle controller and the motor, and is used for receiving the driving torque or the braking torque output by the whole vehicle controller, controlling the motor to output corresponding torque, feeding back the current motor rotating speed and providing maximum torque information.

The motor is connected with the motor controller and the gearbox, and is used for executing driving or braking torque and transmitting the torque to the gearbox.

The gearbox is connected with the motor and the running system, plays a role in speed changing and torque changing of the motor, and transmits torque to the running system.

And the braking proportional electromagnetic valve is connected with the whole vehicle controller and receives a PWM control signal of the whole vehicle controller to proportionally adjust the opening of the electromagnetic valve.

The hydraulic brake is connected with the braking proportional electromagnetic valve and used for executing mechanical braking.

Preferably, the method further comprises: and the power battery is connected with the motor controller and used for providing motor driving energy or recovering motor braking energy.

Preferably, the running system is connected with the gearbox and comprises an axle and wheels, and is used for running of the vehicle.

In a second aspect, an automatic speed control method for an electric mining dump truck includes the steps of:

step S1: the state of the current retarder switch, the retarder gear position, the gearbox gear and the current vehicle speed are obtained.

Step S2: it is judged whether or not the condition for entering the automatic speed control is satisfied, and if so, step S3 is entered.

Step S3: after the condition of entering the automatic speed control is met, the current ramp condition is obtained through the inclination angle sensor, and the current working condition is obtained.

Step S4: selecting an expected speedometer according to the current working condition, and determining an expected speed basic value according to the gear of the current retarding handle

。

Step S5: and acquiring an acceleration coefficient k, and calculating a final expected vehicle speed value according to the acceleration coefficient k.

Step S6: according to the final expected vehicle speed value, calculating the current required torque through a closed-loop PID control algorithm

。

Step S7: according to the current demand torque

And performing torque distribution to obtain a motor torque request.

Preferably, the step S1 includes the following steps:

the gear of the gearbox is sent to the CAN bus of the whole vehicle through the self-controller of the gearbox, and is obtained through the CAN bus by the controller of the whole vehicle.

The retarder switch and the retarder gear are directly connected with a DI port of the whole vehicle controller in a hard wire mode for detection.

Current vehicle speed

The current motor speed fed back by the motor controller is calculated by the following formula

in the formula ,

for the current rotational speed of the motor, < >>

For the radius of the tire>

For axle reduction ratio>

Is the current reduction ratio of the gearbox.

Preferably, the condition for entering automatic speed control includes:

condition 1: the retarder switch is closed.

Condition 2: the gear of the retarding handle is not neutral.

Condition 3: the gear of the gearbox is the forward gear.

Condition 4: the current vehicle speed is greater than a threshold value.

The above conditions must be met simultaneously.

Preferably, step S3 includes the following steps:

when detecting inclination angle

And duration +.>

And judging that the vehicle is currently in an uphill working condition.

When detecting inclination angle

And duration +.>

And judging that the vehicle is currently in a downhill working condition.

When detecting inclination angle

And duration +.>

And judging that the vehicle is currently in the flat ground working condition.

Otherwise, the current working condition is maintained.

As a preferred embodiment of the present invention,

，/>

，/>

。

preferably, the step S4 includes the following steps:

when the current working condition is a downhill working condition and the gear of the retarding handle is 1, the expected basic value of the vehicle speed is 10km/h.

When the current working condition is a downhill working condition and the gear of the retarding handle is 2, the expected basic value of the vehicle speed is 15km/h.

When the current working condition is a downhill working condition and the gear of the retarding handle is 3, the expected basic value of the vehicle speed is 20km/h.

When the current working condition is a downhill working condition and the gear of the retarding handle is 4, the expected basic value of the vehicle speed is 25km/h.

When the current working condition is an uphill working condition and the gear of the retarding handle is 1, the expected basic value of the speed is 10km/h.

When the current working condition is an uphill working condition and the gear of the retarding handle is 2, the expected basic value of the vehicle speed is 20km/h.

When the current working condition is an uphill working condition and the gear of the retarding handle is 3, the expected basic value of the speed is 30km/h.

When the current working condition is an uphill working condition and the gear of the retarding handle is 4, the expected basic value of the vehicle speed is 35km/h.

When the current working condition is a flat ground working condition and the gear of the retarding handle is 1, the expected basic value of the vehicle speed is 10km/h.

When the current working condition is a flat ground working condition and the gear of the retarding handle is 2, the expected basic value of the vehicle speed is 20km/h.

When the current working condition is a flat ground working condition and the gear of the retarding handle is 3, the expected basic value of the vehicle speed is 30km/h.

When the current working condition is a flat ground working condition and the gear of the retarding handle is 4, the expected basic value of the vehicle speed is 40km/h.

Preferably, the calculation formula of the final expected vehicle speed value is as follows:

wherein, k corresponding to the accelerator opening of 0% -100% is a numerical value between 1 and 2, k corresponding to the brake pedal opening of 0% -100% is a numerical value between 1 and 0, 0% represents no stepping, and 100% represents all stepping.

Preferably, the current required torque

The calculation formula is as follows:

wherein ,

for the desired speed +.>

And the current actual vehicle speed>

Difference of->

；/>

Is a proportionality coefficient; />

Is an integration time constant; />

Is a differential time constant.

Preferably, the step S7 includes the following steps:

s7-1, when the working condition of ascending or leveling is in the condition of the ground, the torque is required

The drive torque is provided by the motor>

Accelerating the vehicle until the vehicle stabilizes at the desired speed +.>

。

S7-2, when the vehicle is in the downhill working condition, the torque is required

The vehicle is decelerated by preferentially applying a braking torque from the motor, when the maximum braking torque that the motor can apply is +.>

The hydraulic brake system cooperates to complete the deceleration of the vehicle, at which point the electric motor provides an electric braking torque +.>

The hydraulic brake provides a mechanical braking torque +.>

. Otherwise, the motor alone provides the required torque +.>

At this time->

Until the vehicle stabilizes to the desired speed +.>

。

Preferably, the step S7 further includes:

the motor controller receives a motor torque request sent by the whole vehicle controller and controls the motor to execute.

The whole vehicle controller adjusts the PWM duty ratio value of the braking proportional electromagnetic valvepTo control the magnitude of the mechanical braking torque and the PWM duty cycle valuepThe calculation formula is as follows:

in the formula ,

for the number of hydraulic brakes>

The amount of braking torque provided for a single brake when fully braked.

The beneficial effects are that: according to the automatic speed control system and method for the electric mining dump truck, when the electric mining dump truck is on level ground or on an ascending slope, the motor provides driving torque, the driving torque is calculated under a vehicle speed closed-loop control algorithm, and stable speed running can be achieved without the need of stepping an accelerator pedal by a driver. Compared with the prior art, the method has the following advantages:

(1) And when the motor can not fully provide the required braking torque, the insufficient braking torque is automatically supplemented by the hydraulic braking system, so that the running at a stable vehicle speed during downhill is ensured.

(2) When the vehicle is on the flat ground or on an ascending slope, the required driving torque is calculated by adopting a vehicle speed closed-loop control algorithm, so that the vehicle can automatically perform stable speed control, and the operation of a driver is released.

(3) And calculating an acceleration coefficient according to the opening degrees of the accelerator pedal and the brake pedal, so that the oil acceleration requirement or the brake requirement can be responded in real time when the automatic speed control is performed.

Drawings

Fig. 1 is a diagram of an automatic speed control system of an electric mining dump truck.

Fig. 2 is a flowchart of an automatic speed control method of the electric mining dump truck.

Detailed Description

The invention will be further described with reference to specific examples.

A first embodiment is an automatic speed control system for an electric mining dump truck, as shown in fig. 1, including: the device comprises a retarding handle, a retarding switch, an accelerator pedal, a brake pedal, an inclination sensor, a whole vehicle controller, a motor, a gearbox, a running system, a braking proportional electromagnetic valve and a hydraulic brake.

And the power battery is connected with the motor controller and is used for providing motor driving energy or recovering motor braking energy.

The traveling system is connected with the gearbox and comprises an axle and wheels, and is used for vehicles to travel.

A second embodiment is an automatic speed control method of an electric mining dump truck, as shown in fig. 2, including the steps of:

The current gear of the gearbox is sent to the CAN bus of the whole vehicle through the self-controller of the gearbox, and therefore the controller of the whole vehicle CAN be obtained through the CAN bus.

The speed-reducing switch and the speed-reducing gear are directly connected with a DI port of the whole vehicle controller in a hard wire mode for detection.

Wherein, the current vehicle speed

/>

in the formula ,

for the current rotational speed of the motor, < >>

For the radius of the tire>

For axle reduction ratio>

Is the current reduction ratio of the gearbox.

Considering the driving safety of the vehicle and being separated from the creep start mode of the vehicle, the following conditions must be satisfied at the same time.

Condition 1: the retarder switch is closed.

Condition 2: the gear of the retarding handle is not neutral.

Condition 3: the gear of the gearbox is the forward gear.

Condition 4: the current vehicle speed is greater than a threshold value, preferably 5km/h.

When detecting inclination angle

And duration +.>

And judging that the vehicle is currently in an uphill working condition.

When detecting inclination angle

And duration +.>

And judging that the vehicle is currently in a downhill working condition.

When detecting inclination angle

And duration +.>

And judging that the vehicle is currently in the flat ground working condition.

Otherwise, the current working condition is maintained.

The angle threshold is defined in consideration of the detection precision of the sensor and the ramp dividing threshold

，/>

. Detection time threshold +.>

。

。

Considering the driving safety, different expected speedometers are selected according to different ramp conditions.

Table 1 shows downhill conditions

Gear of retarding handle	1	2	3	4
					Basic value of desired vehicle speed	10km/h	15km/h	20km/h	25km/h

Table 2 shows the uphill condition

Gear of retarding handle	1	2	3	4
					Basic value of desired vehicle speed	10km/h	20km/h	30km/h	35km/h

Table 3 shows the working conditions of the flat ground

Gear of retarding handle	1	2	3	4
					Basic value of desired vehicle speed	10km/h	20km/h	30km/h	40km/h

After entering automatic speed control, in order to respond to the acceleration and braking demands of a driver in real time, the opening degree of an accelerator and the opening degree of a brake pedal are collected, and an acceleration coefficient k is obtained according to a MAP diagram corresponding to the opening degree-coefficient. The value of k corresponding to the accelerator opening of 0% -100% is a value between 1 and 2, and the value of k corresponding to the brake pedal opening of 0% -100% is a value between 1 and 0 (0% represents not stepping and 100% represents all stepping). And ensures that the braking is prioritized, i.e. when simultaneously depressed, the braking pedal opening coefficient is preferentially responded.

The final desired vehicle speed value is

。

。/>

in the formula ,

-desired vehicle speed->

And the current actual vehicle speed>

Difference of->

；

-a scaling factor;

-an integration time constant;

-a differential time constant;

the value of the parameter needs to be determined by real vehicle test.

When the vehicle is on level ground or is ascending, the required torque is calculated

>0, which is the driving torque. On downhill, the required torque is calculated>

Is the braking torque.

Step S7: according to the current demand torque

And performing torque distribution to obtain a motor torque request.

The drive torque is provided by the motor>

Accelerating the vehicle until the vehicle stabilizes at the desired speed +.>

。

The vehicle being decelerated by preferentially applying braking torque by the motor, when the motor is availableMaximum braking torque->

The hydraulic brake provides a mechanical braking torque +.>

. Otherwise, the motor alone provides the required torque +.>

At this time->

Until the vehicle stabilizes to the desired speed +.>

。

in the formula ,

for the number of hydraulic brakes>

The amount of braking torque provided for a single brake when fully braked. />

Value range->

。pWhen the brake proportion electromagnetic valve is 0%, the brake proportion electromagnetic valve is fully closed, and mechanical brake is not carried out; when the braking proportion electromagnetic valve is 100%, the braking proportion electromagnetic valve is fully opened, and mechanical braking is performed with maximum strength.

The foregoing is only a preferred embodiment of the invention, it being noted that: it will be apparent to those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present invention, and such modifications and adaptations are intended to be comprehended within the scope of the invention.

Claims

1. An automatic speed control system of an electric mining dump truck is characterized in that: comprising the following steps: the device comprises a retarding handle, a retarding switch, an accelerator pedal, a brake pedal, an inclination sensor, a whole vehicle controller, a motor, a gearbox, a running system, a braking proportional electromagnetic valve and a hydraulic brake;

the retarding handle is connected with the whole vehicle controller and is used for providing different vehicle speed gears;

the retarder switch is connected with the whole vehicle controller and is used for judging whether an automatic speed mode is started or not;

the accelerator pedal is connected with the whole vehicle controller and is used for vehicle acceleration requirements;

the brake pedal is connected with the whole vehicle controller and is used for braking the vehicle speed;

the inclination angle sensor is connected with the whole vehicle controller and used for detecting the working condition of the current vehicle on an ascending slope, a flat ground or a descending slope;

the whole vehicle controller is used for controlling the whole vehicle to run and executing the automatic speed control method;

the motor controller is connected with the whole vehicle controller and the motor, and is used for receiving the driving torque or the braking torque output by the whole vehicle controller, controlling the motor to output corresponding torque, feeding back the current motor rotating speed and providing maximum torque information;

the motor is connected with the motor controller and the gearbox, and is used for executing driving or braking torque and transmitting the torque to the gearbox;

the gearbox is connected with the motor and the running system, plays a role in speed changing and torque changing of the motor, and transmits torque to the running system;

the braking proportional electromagnetic valve is connected with the whole vehicle controller and receives a PWM control signal of the whole vehicle controller to proportionally adjust the opening of the electromagnetic valve;

2. The automatic speed control system for an electric mining dump truck according to claim 1, wherein: further comprises: and the power battery is connected with the motor controller and used for providing motor driving energy or recovering motor braking energy.

3. The automatic speed control system for an electric mining dump truck according to claim 2, wherein: the traveling system is connected with the gearbox and comprises an axle and wheels, and is used for vehicles to travel.

4. An automatic speed control method for an electric mining dump truck is characterized by comprising the following steps of: the method comprises the following steps:

step S1: acquiring the state of a current retarder switch, a retarder gear position, a gearbox gear and a current vehicle speed;

step S2: judging whether the condition for entering the automatic speed control is met, and if so, entering step S3;

step S3: after the condition of entering the automatic speed control is met, acquiring the current ramp condition by an inclination angle sensor, and acquiring the current working condition;

；

Step S5: acquiring an acceleration coefficient k, and calculating a final expected vehicle speed value according to the acceleration coefficient k;

；

Step S7: according to the current demand torque

And performing torque distribution to obtain a motor torque request.

5. The automatic speed control method for the electric mining dump truck according to claim 4, wherein: the step S1 comprises the following steps:

the gear of the gearbox is sent to the CAN bus of the whole vehicle through the self-controller of the gearbox, and is obtained through the CAN bus by the controller of the whole vehicle;

the speed reducing switch and the speed reducing gear are directly connected with a DI port of the whole vehicle controller in a hard wire mode for detection;

current vehicle speed

in the formula ,

for the current rotational speed of the motor, < >>

For the radius of the tire>

For axle reduction ratio>

Is the current reduction ratio of the gearbox.

6. The automatic speed control method for the electric mining dump truck according to claim 4, wherein: the condition for entering automatic speed control includes:

condition 1: closing a retarding switch;

condition 2: the gear of the retarding handle is not neutral;

condition 3: the gear of the gearbox is a forward gear;

condition 4: the current vehicle speed is greater than a threshold value;

the above conditions must be met simultaneously.

7. The automatic speed control method for the electric mining dump truck according to claim 4, wherein: the step S3 comprises the following steps:

when detecting inclination angle

And duration +.>

Judging that the current working condition is in an ascending working condition;

when detecting inclination angle

And duration +.>

Judging that the vehicle is currently in a downhill working condition;

when detecting inclination angle

And duration +.>

Judging that the current working condition is in the flat ground;

otherwise, the current working condition is maintained.

8. The automatic speed control method for the electric mining dump truck according to claim 7, wherein:

，

，/>

。

9. the automatic speed control method for the electric mining dump truck according to claim 4, wherein: the step S4 includes the following steps:

when the current working condition is a downhill working condition and the gear of the retarding handle is 1, the expected basic value of the speed is 10km/h;

when the current working condition is a downhill working condition and the gear of the retarding handle is 2, the expected basic value of the speed is 15km/h;

when the current working condition is a downhill working condition and the gear of the retarding handle is 3, the expected basic value of the vehicle speed is 20km/h;

when the current working condition is a downhill working condition and the gear of the retarding handle is 4, the expected basic value of the vehicle speed is 25km/h;

when the current working condition is an uphill working condition and the gear of the retarding handle is 1, the expected basic value of the speed is 10km/h;

when the current working condition is an uphill working condition and the gear of the retarding handle is 2, the expected basic value of the speed is 20km/h;

when the current working condition is an uphill working condition and the gear of the retarding handle is 3, the expected basic value of the speed is 30km/h;

when the current working condition is an uphill working condition and the gear of the retarding handle is 4, the expected basic value of the speed is 35km/h;

when the current working condition is a flat ground working condition and the gear of the retarding handle is 1, the expected basic value of the speed is 10km/h;

when the current working condition is a flat ground working condition and the gear of the retarding handle is 2, the expected basic value of the vehicle speed is 20km/h;

when the current working condition is a flat ground working condition and the gear of the retarding handle is 3, the expected basic value of the speed is 30km/h;

10. The automatic speed control method for the electric mining dump truck according to claim 4, wherein: the final expected vehicle speed value is calculated as follows:

/>