CN116552628A - Torque compensation control method of chassis domain EPS system - Google Patents

Abstract

The invention provides a torque compensation control method of a chassis domain EPS system, which comprises the following steps: collecting current information of a vehicle, and fusing calculated results after oversampling sign expansion, electric power assisting control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack tail end steering characteristic control and steering protection vibration compensation are carried out on the collected information to obtain target power assisting torque; and carrying out quantization noise attenuation compensation on the target power-assisted torque and outputting the target power-assisted torque. The invention is based on an electric power steering control strategy in chassis domain control and has the characteristics of quick response, less hardware, low cost and high safety.

Description

Torque compensation control method of chassis domain EPS system

Technical Field

The invention relates to the technical field of automobile control, in particular to a torque compensation control method of a chassis domain EPS system.

Background

With the progress of society, automobile technology and electronic technology, the conventional power steering system has no longer satisfied the development requirements, and has been developed into an electric power steering system. In the fuzzy self-adjustment of the electric power steering system, the source of the Electric Power Steering (EPS) for providing steering auxiliary power is a motor, the driving motor is the current provided by a vehicle-mounted storage battery, and when the vehicle runs at a high speed, namely the steering does not need power assistance or even damping power assistance, the storage battery only needs to provide small control current at the moment, so that the vehicle-mounted electric power steering system meets the development requirements of modern automobiles.

An Electric Power Steering (EPS) system is formed by adding a motor, various sensor devices, an electronic control device, a speed reducing mechanism and the like on the basis of a traditional mechanical steering system, and can provide proper steering power for a driver under different driving conditions such as different vehicle speeds, different torques and the like.

The main problem existing in the prior art is that the distributed power system architecture determines that the corresponding real-time performance of the Electronic Power Steering (EPS) is deficient, and signals such as steering torque signals, vehicle speed signals, steering angle signals, motor speed signals and the like need to be collected, control operation is carried out on the signals, and finally, the current value of the control motor is output. The time required for collecting signals to control and calculate the current required by the output torque is long, and a certain response lag exists subjectively, so that the driving hand feeling of a driver is influenced.

At present, the control mode of the electric power steering system of various automobiles has certain limitation, and the specific method is as follows:

1. a torque sensor of the electric power steering system detects steering torque, steering angle and steering speed signals applied on a steering wheel by a driver, and a vehicle speed sensor detects running speed and engine rotating speed signals of a current vehicle;

the CAN signal transmits the signals of the measured moment, steering angle, steering speed signal, vehicle speed, engine rotating speed and the like to the electronic control unit;

the ECU (electronic control unit) calculates ideal target current according to a self power-assisting characteristic curve chart and a control strategy, so that the ideal target current is converted into current for controlling the motor and the rotating direction of the motor;

4. the motor generates power-assisted torque according to the current output by the ECU, the power-assisted torque is transmitted to the steering mechanism through the speed reducing mechanism, and the power-assisted torque and the steering torque of the driver overcome the steering resistance torque together, so that the driver is provided with proper power assistance.

The above are all control strategies based on the control unit.

When the driver has steering intention, the steering wheel torque is changed, the control unit collects vehicle speed information and torque change, current vehicle information (such as vehicle speed, motor speed, steering torque and the like) is received through the CAN signal, and the target current and the target torque requirement are recalculated. The drawbacks of this case are mainly as follows:

a certain response delay exists, and the response has hysteresis;

the signal on CAN communication is easy to be subjected to electromagnetic interference to cause frame loss, so that the safety is reduced;

the large number of motors and controllers results in excessive costs.

In view of the drawbacks of the above strategies, a new electric power steering control strategy needs to be provided.

Disclosure of Invention

Aiming at the technical problems in the prior art, the invention provides a torque compensation control method of a chassis domain EPS system, which is based on an electric power steering control strategy in chassis domain control and has the characteristics of quick response, less hardware, low cost and high safety.

The technical scheme for solving the technical problems is as follows: a torque compensation control method of a chassis domain EPS system, comprising:

collecting current information of a vehicle, and fusing calculated results after oversampling sign expansion, electric power assisting control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack tail end steering characteristic control and steering protection vibration compensation are carried out on the collected information to obtain target power assisting torque; and carrying out quantization noise attenuation compensation on the target power-assisted torque and outputting the target power-assisted torque.

On the basis of the technical scheme, the invention can also make the following improvements.

Optionally, the collected current information of the vehicle at least includes:

steering torque, motor speed, control vehicle speed, friction torque, LPF (low pass filter) cut-off frequency ratio, steering angle, PDC compensation (offset compensation) torque, left steering maximum angle signal, right steering maximum angle signal, rack angle use permission flag signal, steering angle operand use permission flag, and steady post-compensation assist torque.

Optionally, performing oversampled symbol dilation includes:

and (3) performing oversampling sign expansion on the steering torque and motor speed signals, and outputting the steering torque after sign expansion, the motor speed after sign expansion and the steering speed signals after sign expansion.

Optionally, performing electric power control includes:

the vehicle speed signal, the sign-expanded steering torque signal, the sign-expanded motor speed signal, the friction torque signal and the LPF cut-off frequency ratio signal are input to an electric power control module, and steering torque LPF processing, basic power torque processing, responsive phase compensation processing, SAT (Self-calibration torque) compensation processing and hysteresis compensation processing are performed, respectively, to output electric power control torque and LPF post-steering torque signals.

Optionally, performing vehicle characteristic compensation includes:

the sign-extended steering angular velocity signal, the steering angular signal, the LPF-post steering torque signal, the sign-extended steering torque signal, and the sign-extended motor velocity signal are input to a vehicle characteristic compensation module, and SW (software) steering angle & steering velocity calculation processing, damping control processing, steering wheel return velocity torque processing, active return control processing, and angle control compensation torque calculation processing are performed, respectively, to output a return velocity torque signal and an angle control compensation torque signal.

Optionally, performing motor characteristic compensation includes:

the sign-extended motor speed signal, the sign-extended steering torque signal, the LPF-rear steering torque signal, and the control vehicle speed signal are input to a motor characteristic compensation module, and torque differential compensation processing, torque 2 differential compensation processing, motor inertia compensation processing, motor EMF compensation processing, and motor torque loss compensation processing are performed, respectively, to output a differential torque signal, a 2 differential torque signal, a motor characteristic compensation torque signal, and a friction torque signal.

Optionally, performing stabilization compensation includes:

and inputting the electric power-assisted control torque signal, the differential torque signal and the return speed torque signal into a stabilization compensation module, and respectively carrying out signal splitting processing, addition synthesis signal processing and phase compensation processing to output a stabilized and compensated power-assisted torque signal.

Optionally, performing the rack end steering characteristic control includes:

the stable compensated power-assisted torque signal, the steering angle signal, the sign-expanded steering angular velocity signal, the sign-expanded steering torque signal, the control vehicle speed signal, the left steering maximum angle signal, the right steering maximum angle signal, the rack steering angle use permission mark signal and the steering angle steering speed use permission mark signal are input into a rack tail end steering characteristic control module for carrying out rack tail end limiting processing so as to output the rack tail end compensated power-assisted torque signal.

Optionally, performing rudder protection vibration compensation includes:

the power-assisted torque signal after the tail end compensation of the rack, the 2-time differential torque signal, the angle control compensation torque signal, the PDC compensation torque signal, the steering torque signal after the sign expansion and the control vehicle speed signal are input into a steering protection vibration compensation module, and LPF cut-off frequency judgment processing and target power-assisted torque LPF processing are respectively carried out to output the steering protection vibration compensation power-assisted torque signal.

Optionally, the fusing the calculated result to obtain the target power-assisted torque includes:

and (3) fusing the motor characteristic compensation torque, the stabilized compensated power-assisted torque and the rudder-protecting vibration compensated power-assisted torque input addition part to obtain the target power-assisted torque.

The invention provides a torque compensation control method of a chassis domain EPS system, which is based on an electric power steering control strategy in chassis domain control. The method can obtain smaller return back complementary angle and faster steering wheel return speed, has fast signal response and obviously improves return efficiency, and greatly improves the safety of the vehicle during high-speed running; the hardware involved in control is less, and the hardware cost is low; the steering control device can obtain proper steering force and comfortable steering control characteristics when a driver steers, and can properly sense the motion state of the vehicle and realize smoother, quieter and reliable driving experience.

Drawings

FIG. 1 is a schematic diagram of the working principle of an EPS system;

FIG. 2 is a schematic workflow diagram of an EPS system;

fig. 3 is a schematic diagram of functional modules of the torque compensation control method provided by the invention.

Detailed Description

The following describes in further detail the embodiments of the present invention with reference to the drawings and examples. The following examples are illustrative of the invention and are not intended to limit the scope of the invention.

Fig. 1 is a schematic diagram of the working principle of the EPS system. As shown in fig. 1, the EPS system operates on the following principles: the torque sensor of the EPS system measures the steering torque applied by a driver on a steering wheel, the speed sensor measures signals such as the running speed and the engine rotating speed of the current automobile, the signals are transmitted to the Electronic Control Unit (ECU) through a circuit, and the ECU calculates ideal target current according to the self power-assisted characteristic curve and the control strategy, so that the current and the motor steering direction of the power-assisted motor are controlled; the booster motor then generates a booster torque which is transmitted to the steering mechanism via the transmission. When the EPS system fails, the power-assisted motor does not provide power; when the automobile runs straight, the electronic control unit does not send a steering instruction to the motor, and the power-assisted motor does not work.

Fig. 2 is a schematic workflow diagram of the EPS system. Based on the operation principle of fig. 1, as shown in fig. 2, after confirming that a steering command is issued, the ECU collects sensor signals of the vehicle to perform signal processing and calculation, and outputs a target current for controlling the assist motor; the target current passes through the motor to generate proper power-assisted torque; the power-assisted torque of the motor drives the steering mechanism to carry out steering power-assisted operation after passing through the transmission device, so that the steering control of the vehicle is realized.

Fig. 3 is a schematic diagram of functional modules of a torque compensation control method according to an embodiment of the present invention. The present invention aims to provide an Electronic Power Steering (EPS) system that satisfies a comfortable steering experience for a driver, and based on the above requirements, as shown in fig. 3, an EPS controller includes the following functional modules shown in fig. 3: oversampling symbol expansion, electric assist control, vehicle characteristic compensation, motor characteristic compensation, stabilization compensation, rack end steering characteristic control, steering protection vibration compensation, and quantization noise reduction compensation. The 8 functional modules work cooperatively to form the electronic power steering system.

The torque compensation control method of the chassis domain EPS system provided by the embodiment of the invention comprises the following steps:

collecting current information of a vehicle, and fusing calculated results after oversampling sign expansion, electric power assisting control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack tail end steering characteristic control and steering protection vibration compensation are carried out on the collected information to obtain target power assisting torque; and carrying out quantization noise attenuation compensation on the target power-assisted torque and outputting the target power-assisted torque.

It can be appreciated that, based on the defects in the background technology, the embodiment of the invention provides a torque compensation control method of a chassis domain EPS system, which is based on an electric power steering control strategy in chassis domain control. The method can obtain smaller return back complementary angle and faster steering wheel return speed, has fast signal response and obviously improves return efficiency, and greatly improves the safety of the vehicle during high-speed running; the hardware cost is low because less hardware participates in control; the steering control device can obtain proper steering force and comfortable steering control characteristics when a driver steers, and can properly sense the motion state of the vehicle and realize smoother, quieter and reliable driving experience.

In a possible embodiment, as shown in fig. 3, the collected current information of the vehicle at least includes:

steering torque, motor speed, control vehicle speed, friction torque, LPF (low pass filter) cut-off frequency ratio, steering angle, PDC compensation (offset compensation) torque, left steering maximum angle signal (rel_l_max), right steering maximum angle signal (rel_r_max), rack angle use permission flag signal (rel_end_vld), steering angle operand use permission flag, and steady post-compensation assist torque.

It will be appreciated that some of the vehicle current information comes from sensors of the vehicle EPS system, such as steering torque, motor speed, control vehicle speed, steering angle; and some information is output from each functional module, such as friction torque, LPF (low pass filter) cut-off frequency ratio, PDC compensation (deviation compensation) torque, left rudder maximum angle signal, right rudder maximum angle signal, rack angle use permission flag signal, steering angle operand use permission flag, and post-stability compensation assist torque.

In one possible embodiment, performing oversampled symbol dilation includes:

and (3) performing oversampling sign expansion on the steering torque and motor speed signals, and outputting the steering torque after sign expansion, the motor speed after sign expansion and the steering speed signals after sign expansion.

It will be appreciated that the oversampled symbol-expansion consists of a moving weighted average of the signed expansion to improve the accuracy of the input signal.

In one possible embodiment, the electric assist control includes:

the vehicle speed signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, the friction torque signal and the LPF cut-off frequency proportion signal are input into an electric power-assisted control module to respectively perform steering torque LPF processing, basic power-assisted torque processing, responsive phase compensation processing, SAT compensation processing and hysteresis compensation processing so as to output electric power-assisted control torque and the steering torque signal after LPF.

It is understood that by performing electric assist control on the vehicle speed signal, the sign-expanded steering torque signal, the sign-expanded motor speed signal, and the friction torque signal, quiet and smooth electric assist can be obtained.

In one possible embodiment, as shown in fig. 3, the vehicle characteristic compensation is performed, including:

the sign-extended steering angular velocity signal, the steering angle signal, the LPF-rear steering torque signal, the sign-extended steering torque signal, and the sign-extended motor velocity signal are input to a vehicle characteristic compensation module, and SW steering angle & steering velocity calculation processing, damping control processing, steering wheel return-to-normal velocity torque processing, active return-to-normal control processing, and angle control compensation torque calculation processing are performed, respectively, to output a return-to-normal velocity torque signal and an angle control compensation torque signal.

It is to be understood that the vehicle characteristic compensation module is constituted by a return position control, a return speed control, and a damping control, and that the driver can be made to appropriately perceive the vehicle condition by steering through the vehicle characteristic compensation.

In one possible embodiment, the motor characteristic compensation is performed, including:

the sign-extended motor speed signal, the sign-extended steering torque signal, the LPF-rear steering torque signal, and the control vehicle speed signal are input to a motor characteristic compensation module, and torque differential compensation processing, torque 2 differential compensation processing, motor inertia compensation processing, motor EMF compensation processing, and motor torque loss compensation processing are performed, respectively, to output a differential torque signal, a 2 differential torque signal, a motor characteristic compensation torque signal, and a friction torque signal.

It can be appreciated that the inertia and magnetic torque loss of the motor can be reduced to a certain extent by the motor characteristic compensation, and the accuracy of torque control is improved.

In one possible embodiment, the stabilization compensation is performed, including:

and inputting the electric power-assisted control torque signal, the differential torque signal and the return speed torque signal into a stabilization compensation module, and respectively carrying out signal splitting processing, addition synthesis signal processing and phase compensation processing to output a stabilized and compensated power-assisted torque signal.

It can be understood that the stability compensation module is mainly composed of stability phase compensation and robust stability compensation, and processes the electric power control torque signal output by the electric power control module, the differential torque signal output by the motor characteristic compensation module and the return speed torque signal output by the vehicle characteristic compensation module, so that a driver can obtain comfortable steering control characteristics.

In one possible embodiment, the rack end steering characteristic control includes:

the stable compensated power-assisted torque signal, the steering angle signal, the sign-expanded steering angular velocity signal, the sign-expanded steering torque signal, the control vehicle speed signal, the left steering maximum angle signal, the right steering maximum angle signal, the rack steering angle use permission mark signal and the steering angle steering speed use permission mark signal are input into a rack tail end steering characteristic control module for carrying out rack tail end limiting processing so as to output the rack tail end compensated power-assisted torque signal.

It can be understood that the steering characteristic control module at the tail end of the rack is mainly formed by limiting the tail end of the rack and is used for limiting the electric power assisting at the tail end of the rack, protecting the gear and improving the safety of the vehicle.

In one possible embodiment, performing rudder protection vibration compensation includes:

the power-assisted torque signal after the tail end compensation of the rack, the 2-time differential torque signal, the angle control compensation torque signal, the PDC compensation torque signal, the steering torque signal after the sign expansion and the control vehicle speed signal are input into a steering protection vibration compensation module, and LPF cut-off frequency judgment processing and target power-assisted torque LPF processing are respectively carried out to output the steering protection vibration compensation power-assisted torque signal.

It can be understood that the rudder-protecting vibration compensation module is mainly composed of low-pass cut-off frequency calculation and power-assisting torque low-pass filtering, and quantization noise caused by steering can be reduced through rudder-protecting vibration compensation.

In one possible embodiment, the fusing the calculated result to obtain the target assist torque includes:

and (3) fusing the motor characteristic compensation torque, the stabilized compensated power-assisted torque and the rudder-protecting vibration compensated power-assisted torque input addition part to obtain the target power-assisted torque.

Since the target assist torque output from the adder has a certain noise, the target assist torque output from the adder is subjected to quantization noise attenuation compensation, and then the filtered target assist torque is obtained and output as shown in fig. 3.

The invention provides a torque compensation control method of a chassis domain EPS system, which is based on an electric power steering control strategy in chassis domain control. The method can obtain smaller return back complementary angle and faster steering wheel return speed, has fast signal response and obviously improves return efficiency, and greatly improves the safety of the vehicle during high-speed running; the hardware involved in control is less, and the hardware cost is low; the steering control device can obtain proper steering force and comfortable steering control characteristics when a driver steers, and can properly sense the motion state of the vehicle and realize smoother, quieter and reliable driving experience.

In the foregoing embodiments, the descriptions of the embodiments are focused on, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.

It will be appreciated by those skilled in the art that embodiments of the present invention may be provided as a method, system, or computer program product. Accordingly, the present invention may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present invention may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The present invention is described with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems) and computer program products according to embodiments of the invention. It will be understood that each flow and/or block of the flowchart illustrations and/or block diagrams, and combinations of flows and/or blocks in the flowchart illustrations and/or block diagrams, can be implemented by computer program instructions. These computer program instructions may be provided to a processor of a general purpose computer, special purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, create means for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the instructions stored in the computer-readable memory produce an article of manufacture including instruction means which implement the function specified in the flowchart flow or flows and/or block diagram block or blocks.

These computer program instructions may also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer implemented process such that the instructions which execute on the computer or other programmable apparatus provide steps for implementing the functions specified in the flowchart flow or flows and/or block diagram block or blocks.

While preferred embodiments of the present invention have been described, additional variations and modifications in those embodiments may occur to those skilled in the art once they learn of the basic inventive concepts. It is therefore intended that the following claims be interpreted as including the preferred embodiments and all such alterations and modifications as fall within the scope of the invention.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention also include such modifications and alterations insofar as they come within the scope of the appended claims or the equivalents thereof.

Claims (10)

1. A torque compensation control method of a chassis domain EPS system, comprising:

collecting current information of a vehicle, and fusing calculated results after oversampling sign expansion, electric power assisting control, motor characteristic compensation, vehicle characteristic compensation, stabilization compensation, rack tail end steering characteristic control and steering protection vibration compensation are carried out on the collected information to obtain target power assisting torque; and carrying out quantization noise attenuation compensation on the target power-assisted torque and outputting the target power-assisted torque.

2. The method for controlling torque compensation of a chassis domain EPS system according to claim 1, wherein the collected current information of the vehicle comprises at least:

steering torque, motor speed, control vehicle speed, friction torque, LPF cut-off frequency proportion, steering angle, PDC compensation torque, left steering maximum angle signal, right steering maximum angle signal, rack angle use permission mark signal, steering angle operation use permission mark and stable compensated power-assisted torque.

3. A torque compensation control method of a chassis domain EPS system according to claim 1 or 2, characterized by performing oversampled sign expansion, comprising:

and (3) performing oversampling sign expansion on the steering torque and motor speed signals, and outputting the steering torque after sign expansion, the motor speed after sign expansion and the steering speed signals after sign expansion.

4. A torque compensation control method of a chassis domain EPS system according to claim 3, characterized by performing electric assist control, comprising:

the vehicle speed signal, the steering torque signal after sign expansion, the motor speed signal after sign expansion, the friction torque signal and the LPF cut-off frequency proportion signal are input into an electric power-assisted control module to respectively perform steering torque LPF processing, basic power-assisted torque processing, responsive phase compensation processing, SAT compensation processing and hysteresis compensation processing so as to output electric power-assisted control torque and the steering torque signal after LPF.

5. The method of torque compensation control of a chassis domain EPS system according to claim 4, characterized by performing vehicle characteristic compensation, comprising:

the sign-extended steering angular velocity signal, the steering angle signal, the LPF-rear steering torque signal, the sign-extended steering torque signal, and the sign-extended motor velocity signal are input to a vehicle characteristic compensation module, and SW steering angle & steering velocity calculation processing, damping control processing, steering wheel return-to-normal velocity torque processing, active return-to-normal control processing, and angle control compensation torque calculation processing are performed, respectively, to output a return-to-normal velocity torque signal and an angle control compensation torque signal.

6. The method of torque compensation control of a chassis domain EPS system according to claim 5, characterized by performing motor characteristic compensation, comprising:

the sign-extended motor speed signal, the sign-extended steering torque signal, the LPF-rear steering torque signal, and the control vehicle speed signal are input to a motor characteristic compensation module, and torque differential compensation processing, torque 2 differential compensation processing, motor inertia compensation processing, motor EMF compensation processing, and motor torque loss compensation processing are performed, respectively, to output a differential torque signal, a 2 differential torque signal, a motor characteristic compensation torque signal, and a friction torque signal.

7. The method of torque compensation control of a chassis domain EPS system according to claim 6, wherein performing stabilization compensation comprises:

and inputting the electric power-assisted control torque signal, the differential torque signal and the return speed torque signal into a stabilization compensation module, and respectively carrying out signal splitting processing, addition synthesis signal processing and phase compensation processing to output a stabilized and compensated power-assisted torque signal.

8. The method of torque compensation control of a chassis domain EPS system according to claim 7, characterized by performing rack end steering characteristic control, comprising:

the stable compensated power-assisted torque signal, the steering angle signal, the sign-expanded steering angular velocity signal, the sign-expanded steering torque signal, the control vehicle speed signal, the left steering maximum angle signal, the right steering maximum angle signal, the rack steering angle use permission mark signal and the steering angle steering speed use permission mark signal are input into a rack tail end steering characteristic control module for carrying out rack tail end limiting processing so as to output the rack tail end compensated power-assisted torque signal.

9. The method for torque compensation control of a chassis domain EPS system according to claim 8, wherein performing rudder-protecting vibration compensation comprises:

the power-assisted torque signal after the tail end compensation of the rack, the 2-time differential torque signal, the angle control compensation torque signal, the PDC compensation torque signal, the steering torque signal after the sign expansion and the control vehicle speed signal are input into a steering protection vibration compensation module, and LPF cut-off frequency judgment processing and target power-assisted torque LPF processing are respectively carried out to output the steering protection vibration compensation power-assisted torque signal.

10. The method for torque compensation control of a chassis domain EPS system according to claim 9, wherein the fusing the calculated result to obtain the target assist torque comprises:

and (3) fusing the motor characteristic compensation torque, the stabilized compensated power-assisted torque and the rudder-protecting vibration compensated power-assisted torque input addition part to obtain the target power-assisted torque.