CN111017005A - Torque control method and system for electric power-assisted transport vehicle - Google Patents
Torque control method and system for electric power-assisted transport vehicle Download PDFInfo
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- CN111017005A CN111017005A CN201811180368.5A CN201811180368A CN111017005A CN 111017005 A CN111017005 A CN 111017005A CN 201811180368 A CN201811180368 A CN 201811180368A CN 111017005 A CN111017005 A CN 111017005A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D5/00—Power-assisted or power-driven steering
- B62D5/04—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear
- B62D5/0457—Power-assisted or power-driven steering electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear characterised by control features of the drive means as such
- B62D5/046—Controlling the motor
Abstract
The invention relates to a torque control method and a system of an electric power-assisted transport vehicle. Specifically, a linear type assistance characteristic curve is adopted, and the assistance characteristic curve comprises three regions: a non-power-assisted area, a power-assisted variable area and a power-assisted constant area; when the vehicle is in parking, low-speed steering or middle-high-speed driving steering, the driving speed sensor detects the driving speed of the vehicle, the detected signal is transmitted to the control unit to have corresponding boosting characteristics, and different boosting currents are applied to the motor to change the rotating speed of the motor, so that the variability of torque during steering is achieved, and good steering control road feel is ensured. The problem that the existing torque control method is complex in calculation is solved.
Description
Technical Field
The invention belongs to the technical field of automobile steering, and particularly relates to a torque control method and system for an electric power-assisted transport vehicle.
Background
Currently, most automobiles still adopt a hydraulic power steering system (HPS), and the power-assisted characteristic of the steering system is fixed, namely the power-assisted steering is not adjusted correspondingly with the change of the automobile speed. An electric power steering system (EPS) and an Electric Hydraulic Power System (EHPS) can make an automobile light and stable during low-speed steering, but are not suitable for heavy vehicles with large front axle loads due to limited power. The steering feel and road feel of a driver at each vehicle speed depend on the power-assisted characteristic of the ECHPS, and the power-assisted characteristic of the ECHPS at each vehicle speed is related to the structural parameters of the rotary valve and the flow entering the rotary valve.
The torque control method is various, the traditional control method is low in control precision, poor in robustness and long in response time, and therefore the assisting force provided by the motor is delayed, and great influence is brought to the comfort and the safety of the automobile. In addition, the traditional method needs to perform a large amount of calculation for fitting the steering assistance curve, and the method is complex for calculating the response assistance current for each torque measurement.
Disclosure of Invention
The invention aims to provide a torque control method of an electric power-assisted transport vehicle, which is used for solving the problem that the existing torque control method is complex in calculation.
In order to solve the technical problems, the technical scheme of the invention is as follows:
the invention provides a torque control method of an electric power-assisted transport vehicle, which comprises the following steps:
1) detecting the torque of a steering wheel during steering;
2) if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value;
3) and adjusting the output power of the booster motor according to the booster characteristic of the booster motor corresponding to the current torque.
The invention also provides a torque control system of the electric power-assisted transport vehicle, which comprises a processing unit and a storage unit, wherein the processing unit executes instructions stored in the storage unit to realize the following method steps:
1) detecting the torque of a steering wheel during steering;
2) if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value;
3) and adjusting the output power of the booster motor according to the booster characteristic of the booster motor corresponding to the current torque.
The invention has the beneficial effects that:
when the vehicle turns, the torque of a steering wheel is detected, a signal is transmitted to the controller, the controller performs corresponding control on the motor after analysis and processing, and the torque output by the motor is transmitted to the rack-and-pinion steering gear through the speed reducing mechanism and is finally output to a steering wheel through the transmission shaft. Specifically, a linear type assistance characteristic curve is adopted, and the assistance characteristic curve comprises three regions: a non-power-assisted area, a power-assisted variable area and a power-assisted constant area; when the vehicle is in parking, low-speed steering or middle-high-speed driving steering, the driving speed sensor detects the driving speed of the vehicle, the detected signal is transmitted to the control unit to have corresponding boosting characteristics, and different boosting currents are applied to the motor to change the rotating speed of the motor, so that the variability of torque during steering is achieved, and good steering control road feel is ensured. The problem that the existing torque control method is complex in calculation is solved.
Further, the boosting characteristic of the boosting motor is represented by a boosting current I of the boosting motor, and is represented as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxFor a second set torque value, K is a constant, ImaxThe maximum boosting current provided by the boosting motor.
Further, when the current torque is greater than the first set torque value and less than the second set torque value, the larger the vehicle speed, the smaller the magnitude of the boost characteristic increase with the increase in the current torque.
Further, the boosting characteristic of the boosting motor is represented by a boosting current I of the boosting motor, and is represented as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxFor a second set torque value, K (v) is a running speed inductance, ImaxThe maximum boosting current provided by the boosting motor.
Drawings
FIG. 1 is a schematic view of a steering system according to an embodiment of the present invention;
FIG. 2 is a schematic view of a power assist characteristic of a second embodiment of the method of the present invention;
in the figure, 1-a steering wheel, 2-a torque sensor, 3-a speed reducing mechanism, 4-a control unit, 5-an assisting motor, 6-a rack and pinion steering gear, 7-a steering rocker arm, 8-a wheel, 9-an input shaft, 10-an output shaft and Va-a vehicle speed sensor.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention clearer, the present invention is further described in detail below with reference to the accompanying drawings and embodiments.
The structure of the vehicle steering system is shown in fig. 1, wherein a steering wheel 1 is connected with an input shaft 9; the control unit 4 is respectively connected with the torque sensor 2, the power-assisted motor 5 and the vehicle speed sensor Va; the torque sensor 2 is connected with the input shaft 9; the power-assisted motor 5 is connected to an input shaft 9 through a speed reducing mechanism 3, and the input shaft 9 is connected with a rack and pinion steering gear 6; the rack and pinion steering gear 6 is arranged on an output shaft 10, two ends of the output shaft are connected with steering rocker arms 7, and the steering rocker arms 7 control wheels 8.
When the steering wheel steering device works, when a driver operates the steering wheel 1, the torque sensor 2 detects the torque of the steering wheel 1 in real time, the control unit 4 analyzes and processes signals acquired by the torque sensor 2, outputs signals for controlling the power-assisted motor 5 according to the power-assisted characteristic of the current torque corresponding to the steering motor, controls the rotating speed of the power-assisted motor 5 in real time, transmits the signals to the rack-and-pinion steering device 6 through the input shaft 9, and transmits the signals to the steering rocker arm 7 through the output shaft 10 by the rack-and-pinion steering device 6, so that the wheels 8 are driven to steer.
The first embodiment of the method of the invention:
1) detecting the torque of a steering wheel during steering; the torque sensor 2 detects the torque of the steering wheel in real time, and the control unit receives the steering wheel torque sensor;
2) and (3) judging: if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value; and judging by combining the power-assisted characteristic curve to obtain the current power-assisted current I, wherein the power-assisted characteristic curve function is as follows:
wherein, Td0Is a first set torque value representing the steering wheel torque at the start of the assistance motor, TdmaxIs a second set torque value representing the steering wheel torque corresponding to the maximum assistance provided by the assistance motor 5, K is a constant, ImaxMaximum assistance current, T, supplied to the assistance motor 5dIs the current torque detected by the steering wheel torque sensor.
It can be seen that the power assist characteristic curve is divided into three intervals: a non-power-assisted area, a power-assisted variable area and a power-assisted constant area; the non-power-assisted area corresponds to the condition that the current torque is smaller than a first set torque value, the power-assisted change area corresponds to the condition that the current torque is larger than the first set torque value and smaller than a second set torque value, and the power-assisted constant area corresponds to the condition that the current torque is larger than the second set torque value; the steering wheel torque sensor detects the current steering wheel torque.
When the current torque of the steering wheel is less than or equal to T and 0d＜Td0When the vehicle is in a non-power-assisted area, the power-assisted motor 5 does not assist the steering of the vehicle, and the power-assisted current is 0; when the current torque T of the steering wheeld0≤Td＜TdmaxWhen the vehicle is in the boosting change area, the value of the boosting current is I ═ K (T) at the momentd-Td0) When the current torque T of the steering wheeld≥TdmaxWhen the vehicle is in the power-assisted constant region, the maximum power-assisted current I is applied to the power-assisted motor 5maxThe power-assisted steering device is used for assisting the steering of the vehicle.
3) Adjusting the output power of the power-assisted motor according to the power-assisted characteristic of the power-assisted motor corresponding to the current torque; by partitioning the power-assisted characteristic curve, the power-assisted current corresponding to each torque does not need to be calculated during control, and only the measured current torque of the steering wheel is combined with the power-assisted characteristic curve to find out the interval corresponding to the current torque, and then the power-assisted current corresponding to the interval is applied to the power-assisted motor to assist in steering.
Method embodiment two of the invention
1) Detecting the torque of a steering wheel during steering; the torque sensor 2 detects the torque of a steering wheel in real time, the vehicle speed sensor Va detects the current vehicle speed, and the control unit receives signals detected by the steering wheel torque sensor and the speed sensor;
2) and (3) judging: if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value; the current assist current I is obtained by combining with the assist characteristic curve judgment, as shown in fig. 2, the assist characteristic curve function is:
wherein, Td0Is a first set torque value representing the steering wheel torque at the start of the assistance motor, TdmaxA second set torque value representing the steering wheel torque corresponding to the maximum power provided by the power motor 5, K (v) being a running speed inductance, the higher the vehicle speed, the smaller K (v), ImaxMaximum assistance current, T, supplied to the assistance motor 5dIs the current torque detected by the steering wheel torque sensor.
It can be seen that the power assist characteristic curve is divided into three intervals: a non-power-assisted area, a power-assisted variable area and a power-assisted constant area; the non-power-assisted area corresponds to the condition that the current torque is smaller than a first set torque value, the power-assisted change area corresponds to the condition that the current torque is larger than the first set torque value and smaller than a second set torque value, and the power-assisted constant area corresponds to the condition that the current torque is larger than the second set torque value; the steering wheel torque sensor detects the current steering wheel torque.
When the current torque of the steering wheel is less than or equal to T and 0d＜Td0When the vehicle is in a non-power-assisted area, the power-assisted motor 5 does not assist the steering of the vehicle, and the power-assisted current is 0; when the current torque T of the steering wheeld0≤Td＜TdmaxWhen the vehicle is in the boosting change area, the value of the boosting current is I ═ K (v) (T)d-Td0) The higher the vehicle speed, the smaller K (v); when the current torque T of the steering wheeld≥TdmaxWhen the vehicle is in the power-assisted constant region, the maximum power-assisted current I is applied to the power-assisted motor 5maxThe power-assisted steering device is used for assisting the steering of the vehicle.
3) Adjusting the output power of the power-assisted motor according to the power-assisted characteristic of the power-assisted motor corresponding to the current torque; by partitioning the power-assisted characteristic curve, the power-assisted current corresponding to each torque does not need to be calculated during control, only the measured current torque and the current speed of the steering wheel are needed, then the section corresponding to the current torque is found out by combining the power-assisted characteristic curve, and then the power-assisted current corresponding to the section is applied to the power-assisted motor to be the steering power assistance.
The second method embodiment differs from the first method embodiment only in that the constant K is a function of the driving speed response K (v), K (v) relating to the driving speed v of the vehicle.
In the above embodiment, the assist characteristic of the assist motor is adjusted by controlling the assist current of the assist motor. As another embodiment, the adjustment of the boosting characteristic of the boosting motor can be realized by controlling the voltage or the power.
The system embodiment of the invention:
the system for implementing the first method embodiment comprises a vehicle control unit and a detection module for acquiring the torque, wherein the vehicle control unit comprises a processing unit and a storage unit, and the processing unit executes a program stored in the storage unit so as to implement the steps of the first method embodiment.
The system for implementing the second embodiment of the method comprises a vehicle control unit and a detection module for acquiring the torque and the vehicle running speed, wherein the vehicle control unit comprises a processing unit and a storage unit, and the processing unit executes a program stored in the storage unit so as to implement the steps of the method of the first embodiment of the method.
The processing unit may be a single processor, or may be a processing unit formed by two or more processors.
Claims (8)
1. The torque control method of the electric power-assisted transport vehicle is characterized by comprising the following steps of:
1) detecting the torque of a steering wheel during steering;
2) if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value;
3) and adjusting the output power of the booster motor according to the booster characteristic of the booster motor corresponding to the current torque.
2. The electric assist vehicle torque control method according to claim 1, wherein the assist characteristic of the assist motor is expressed as an assist current I of the assist motor, and is represented as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxFor a second set torque value, K is a constant, ImaxThe maximum boosting current provided by the boosting motor.
3. The electric assist vehicle torque control method according to claim 1, wherein when the current torque is greater than the first set torque value and less than the second set torque value, the magnitude of the increase in the assist characteristic with the increase in the current torque is smaller as the vehicle speed is larger.
4. The electric assist vehicle torque control method according to claim 3, wherein the assist characteristic of the assist motor is expressed as an assist current I of the assist motor, and is represented as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxFor a second set torque value, K (v) is a running speed inductance, ImaxThe maximum boosting current provided by the boosting motor.
5. An electric power assisted transportation vehicle torque control system comprising a processing unit and a memory unit, the processing unit executing instructions stored in the memory unit to implement the method steps of:
1) detecting the torque of a steering wheel during steering;
2) if the current torque is smaller than a first set torque value, the power-assisted characteristic of the power-assisted motor is zero, if the current torque is larger than the first set torque value and smaller than a second set torque value, the power-assisted characteristic of the power-assisted motor is increased along with the increase of the current torque, and if the current torque is larger than the second set torque value, the power-assisted characteristic of the power-assisted motor is a constant value;
3) and adjusting the output power of the booster motor according to the booster characteristic of the booster motor corresponding to the current torque.
6. The electric assist transporter torque control system of claim 5, wherein the assist characteristic of the assist motor is represented by an assist current I of the assist motor as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxFor a second set torque value, K is a constant, ImaxThe maximum boosting current provided by the boosting motor.
7. The electric assist transporter torque control system according to claim 5, wherein the magnitude of the increase in the assist characteristic with an increase in the current torque is smaller as the vehicle speed is larger when the current torque is larger than the first set torque value and smaller than the second set torque value.
8. The electric assist transporter torque control system of claim 7, wherein the assist characteristic of the assist motor is represented by an assist current I of the assist motor as:
wherein, TdFor the current torque detected by the steering wheel torque sensor, Td0Is a first set torque value, TdmaxIs as followsTwo set torque values, K (v) being the driving speed induction coefficient, ImaxThe maximum boosting current provided by the boosting motor.
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| CN201811180368.5A CN111017005A (en) | 2018-10-10 | 2018-10-10 | Torque control method and system for electric power-assisted transport vehicle |
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| CN201811180368.5A CN111017005A (en) | 2018-10-10 | 2018-10-10 | Torque control method and system for electric power-assisted transport vehicle |
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| CN113548110A (en) * | 2021-07-19 | 2021-10-26 | 东风汽车集团股份有限公司 | Continuously adjustable power-assisted steering method, system and computer equipment |
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Application publication date: 20200417 |
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