CN111559424B - Digital line control steering system and control method and device thereof - Google Patents
Digital line control steering system and control method and device thereof Download PDFInfo
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- CN111559424B CN111559424B CN202010412456.4A CN202010412456A CN111559424B CN 111559424 B CN111559424 B CN 111559424B CN 202010412456 A CN202010412456 A CN 202010412456A CN 111559424 B CN111559424 B CN 111559424B
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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
- B62D5/06—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle
- B62D5/09—Power-assisted or power-driven steering fluid, i.e. using a pressurised fluid for most or all the force required for steering a vehicle characterised by means for actuating valves
- B62D5/091—Hydraulic steer-by-wire systems, e.g. the valve being actuated by an electric motor
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D15/00—Steering not otherwise provided for
- B62D15/02—Steering position indicators ; Steering position determination; Steering aids
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Abstract
The invention relates to a digital line control steering system, which is characterized by comprising: the angle sensor is used for acquiring a steering angle signal of a steering wheel; the speed reducing mechanism is used for transmitting a steering torque signal of a steering wheel to the force feedback motor according to a steering angle signal acquired by the angle sensor; one of the first pressure sensor and the second pressure sensor is used for acquiring a first pressure signal on an oil return path of the digital flow reversing valve, the other one of the first pressure sensor and the second pressure sensor is used for acquiring a second pressure signal on an oil outlet path of the digital flow reversing valve, and the displacement sensor is used for acquiring a piston expansion displacement signal of the steering oil cylinder; the controller is used for taking the steering angle signal and the steering torque signal converted by the A/D converter as input signals; the first pressure signal, the second pressure signal and the displacement signal after the conversion of the A/D converter are used as feedback signals; and determining the target step number of the stepping motor according to the input signal and the feedback signal so as to accurately control the opening size of the digital flow reversing valve.
Description
Technical Field
The embodiment of the invention relates to the technical field of engineering machinery, in particular to a digital line control steering system and a control method and equipment thereof.
Background
The loader is suitable for urban construction sites of engineering machines such as highways, railways, ports, wharfs, coals, mines, airports and the like, is mainly used for shoveling, loading, unloading, transporting and the like bulk materials, can also carry out slight shoveling on rocks and hard soil, and is indispensable mechanical equipment for building construction such as national defense engineering, mine construction, urban and rural roads and water conservancy construction and the like.
With the rapid advance of international cooperative construction business in China and the competitive pressure of overseas engineering machinery manufacturers, the requirements on the engineering machinery are not only large in quantity, but also quite high requirements on the technical level of the engineering machinery are provided. With the combination of modern electronic technology, computer technology, communication technology, artificial intelligence technology, sensor technology and other high and new technologies, the traditional loader steering hydraulic system is developing towards digitization.
At present, a steering gear is used for walking and steering of a traditional wheel loader, high-pressure oil of a steering pump enters a steering oil cylinder through the steering gear to control the stretching of a piston of the steering oil cylinder, and the rotation of a hinge point of the loader is realized. In order to solve the problem, a flow amplification technology is introduced along with the update of a loader steering system, namely, a small flow is used for controlling a large flow (the flow of a steering gear acts on a pilot valve core of an electromagnetic directional valve to control the reversing of the electromagnetic valve).
Disclosure of Invention
The invention provides a digital line control steering system and a control method and equipment thereof, which aim to realize the effects of low power consumption, high steering precision, simpler pipeline arrangement, low noise, good stability and the like.
To achieve the above object, an embodiment of an aspect of the present invention provides a digital line steering system, including:
the control end of the digital flow reversing valve is connected with the stepping motor, one side port of the digital flow reversing valve is connected with the fixed displacement pump, and the other side port of the digital flow reversing valve is connected with a steering oil cylinder; the angle sensor is used for acquiring a steering angle signal of a steering wheel; the speed reducing mechanism is respectively connected with the angle sensor and the force feedback motor and is used for transmitting a steering torque signal of the steering wheel to the force feedback motor according to a steering angle signal acquired by the angle sensor; one of the first pressure sensor and the second pressure sensor is used for acquiring a first pressure signal on an oil return path of the digital flow reversing valve, the other one of the first pressure sensor and the second pressure sensor is used for acquiring a second pressure signal on an oil outlet path of the digital flow reversing valve, and the displacement sensor is used for acquiring a piston expansion displacement signal of the steering oil cylinder; the controller is used for taking the steering angle signal and the steering torque signal converted by the A/D converter as input signals; and the first pressure signal, the second pressure signal and the displacement amount signal after the conversion by the a/D converter are used as feedback signals; and determining the target step number of the stepping motor according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve.
According to the digital steer-by-wire system provided by the embodiment of the invention, a steering angle signal and a steering torque signal which are converted by an A/D converter can be used as input signals; the first pressure signal, the second pressure signal and the displacement signal after the conversion of the A/D converter are used as feedback signals; and the target step number of the stepping motor is determined according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve, so that a steering gear is omitted, the flow of a steering pump directly enters a steering cylinder, the use efficiency of the pump is improved, the power of an engine is reasonably distributed, the energy consumption is reduced, and the operation performance of the loader is improved.
Optionally, the digital steer-by-wire system further comprises: and the constant pressure difference valve is used for compensating the pressure values of the inlet and the outlet of the digital flow reversing valve.
Optionally, the digital steer-by-wire system further comprises: and the overflow valve is connected in parallel on an oil way at one side of the digital flow reversing valve, which is connected with the constant delivery pump, and is used for preventing overflow.
In order to achieve the above object, another embodiment of the present invention provides a method for controlling a digital steering system, including:
acquiring the digitized steering angle signal and the digitized steering torque signal as input signals;
acquiring the first pressure signal, the second pressure signal and the displacement signal which are digitized as feedback signals;
and determining the target step number of the stepping motor according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve.
According to the control method of the digital steer-by-wire system provided by the embodiment of the invention, firstly, the digitized steering angle signal and the digitized steering torque signal are obtained as input signals; secondly, acquiring the first pressure signal, the second pressure signal and the displacement signal which are digitized as feedback signals; and finally, determining the target step number of the stepping motor according to the input signal and the feedback signal to determine the opening size of the digital flow reversing valve, so that a steering gear is omitted, the flow of a steering pump directly enters a steering cylinder, the use efficiency of the pump is improved, the power of an engine is reasonably distributed, the energy consumption is reduced, and the operation performance of the loader is improved.
Optionally, the determining a target number of steps of a stepper motor based on the input signal and the feedback signal to determine the opening size of the digital flow reversing valve comprises:
determining an ideal step number of the stepping motor according to the input signal;
determining the actual step number of the stepping motor according to the feedback signal;
acquiring an error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
acquiring the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor according to the error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
determining a target step number of the stepping motor based on a controller according to the error and the error change rate;
and controlling the stepping motor according to the target step number of the stepping motor so as to determine the opening size of the digital flow reversing valve.
Optionally, the determining a target number of steps of the stepping motor based on the controller according to the error and the error change rate further includes:
fuzzifying the error and the error change rate, and performing reasoning and counting by using a preset fuzzy ruleCalculating and analyzing, namely, automatically searching a fuzzy matrix table to carry out parameter setting so as to meet the requirement of errors and error change rates under different states on PID parameter self-setting, and calculating three parameters K of the PIDp，Ti，TdAccording to three parameters K of said PIDp，Ti，TdDetermining a target number of steps of the stepper motor.
Optionally, the obtaining an error between the ideal step number of the stepping motor and the actual step number of the stepping motor is obtaining a step number difference between the ideal step number of the stepping motor and the actual step number of the stepping motor;
and the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor is obtained by calculating the differential value of the step number difference.
In order to achieve the above object, an embodiment of another aspect of the present invention provides an apparatus including the above digital steer-by-wire system.
The equipment may be a loader, a road roller, and other wheeled construction machines, and is not limited herein.
Compared with the prior art, the invention has the following beneficial effects: (1) through the introduction of the digital flow reversing valve, the traditional electric control, hydraulic control and electro-hydraulic control modes are replaced, so that the whole steering system is digital and intelligent. (2) The arrangement of the pressure sensor and the displacement sensor greatly improves the steering control precision, and in an emergency, in order to avoid the misjudgment of a driver, the relevant input of the driver to the steering is ignored, and the stable and safe state of the vehicle is ensured; the method is suitable for high-precision working environment. (3) The pressure difference of the inlet and the outlet of the digital flow reversing valve is compensated by arranging the constant pressure difference valve, so that the pressure difference of the inlet and the outlet of the digital flow reversing valve is kept constant, the steering speed is kept stable, and the pressure loss of a pipeline is reduced. (4) By the arrangement of the overflow valve, the overflow phenomenon at the inlet of the digital flow reversing valve is avoided. (5) The force feedback motor is arranged so that when the steering wheel is rotated to the limit, the steering wheel can automatically turn. In actual operation, the most used of operators is direction control, and the traditional engineering machinery steering wheel is heavy, so that the labor amount of the operators is increased. The digital wire control steering system has light and flexible steering wheel.
Drawings
FIG. 1 is a schematic diagram of a digital steer-by-wire system configuration of an embodiment of the present invention;
FIG. 2 is a flow chart of a digital steer-by-wire system control method of an embodiment of the present invention;
FIG. 3 is a flow chart of a digital steer-by-wire system control method of one embodiment of the present invention;
FIG. 4 is a flow chart of a digital steer-by-wire system control method of one embodiment of the present invention;
fig. 5 is a schematic diagram of a digital steer-by-wire system control method according to an embodiment of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not to be construed as limiting the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Fig. 1 is a schematic diagram of a digital steer-by-wire system according to an embodiment of the present invention. As shown in fig. 1, the digital steer-by-wire system includes:
the device comprises an angle sensor 10, a speed reducer mechanism 11, a force feedback motor 12, an A/D converter 16, a controller 15, a stepping motor 17, a fixed displacement pump 1, a digital flow reversing valve 4, a first pressure sensor 5, a second pressure sensor 13 and at least one displacement sensor, wherein the control end of the digital flow reversing valve 4 is connected with the stepping motor 17, the port of one side of the digital flow reversing valve is connected with the fixed displacement pump 1, and the port of the other side of the digital flow reversing valve is connected with a steering oil cylinder;
the angle sensor 10 is used for acquiring a steering angle signal of the steering wheel 9;
the speed reducer mechanism 11 is respectively connected with the angle sensor 10 and the force feedback motor 12 and is used for transmitting a steering torque signal of the steering wheel 9 to the force feedback motor 12 according to a steering angle signal acquired by the angle sensor 10;
one of the first pressure sensor 5 and the second pressure sensor 13 is used for acquiring a first pressure signal on an oil return path of the digital flow reversing valve, the other one is used for acquiring a second pressure signal on an oil outlet path of the digital flow reversing valve, and the displacement sensor is used for acquiring a piston expansion displacement signal of the steering oil cylinder;
the controller 15 is configured to convert the steering angle signal and the steering torque signal into input signals according to the a/D converter 16; and the first pressure signal, the second pressure signal, and the displacement amount signal after the conversion by the a/D converter 16 as feedback signals; the target number of steps of the stepping motor 17 is determined based on the input signal and the feedback signal to determine the opening size of the digital flow rate switching valve 4.
An angle sensor 10 is arranged below a vehicle steering wheel 9, the angle sensor 10 is connected with a speed reducer mechanism 11, the speed reducer mechanism 11 is connected with a force feedback motor 12, a steering angle signal of the steering wheel 9 is acquired by the angle sensor 10, the force feedback motor 12 feeds back a steering torque signal of the steering wheel 9 according to the steering angle signal, and the angle sensor 10 and the force feedback motor 12 are electrically connected with an input end of an A/D converter 16; the output end of the A/D converter 16 is electrically connected with the input end of the controller 15, the output end of the controller 15 is electrically connected with the stepping motor 17, the stepping motor 17 is electrically connected with the control end of the digital flow reversing valve 4, the inlet of the digital flow reversing valve 4 is connected with the constant delivery pump 1, the outlet of the digital flow reversing valve 4 is connected with the steering oil cylinder, a pressure sensor is arranged on an oil path connecting the outlet of the digital flow reversing valve 4 and the steering oil cylinder, and a displacement sensor for detecting the telescopic displacement of a piston of the steering oil cylinder is arranged on the steering oil cylinder.
The number of the steering cylinders is two, namely a first steering cylinder 7 and a second steering cylinder 8, and each steering cylinder is provided with a displacement sensor for detecting the telescopic displacement of a steering cylinder piston, namely a first displacement sensor 6 and a second displacement sensor 14 which are correspondingly arranged respectively. Pressure sensors, namely a first pressure sensor 5 and a second pressure sensor 13, are arranged on oil paths of the digital flow reversing valve 4 connected with the steering oil cylinder. Each pressure sensor, each displacement sensor is connected to an input of the a/D converter 16.
When the vehicle is parked or is moving straight, as shown in fig. 1, the oil passages of the inlet and the outlet of the digital flow reversing valve 4 are respectively located at the middle transverse position, when the vehicle turns left, the oil passages of the inlet and the outlet of the digital flow reversing valve 4 are respectively located at the left parallel oil passage position in fig. 1, and when the vehicle turns right, the oil passages of the inlet and the outlet of the digital flow reversing valve 4 are respectively located at the right cross oil passage position in fig. 1. It will be appreciated that when turning left, the first pressure sensor 5 detects a pressure signal on the oil line and the second pressure sensor 13 detects a pressure signal on the oil return line; when turning to the right, the first pressure sensor 5 detects a pressure signal on the oil return path, and the second pressure sensor 13 detects a pressure signal on the oil outlet path.
It can be understood that the steering angle signal and the steering torque signal are converted by the a/D converter 16 and then sent to the controller 15, and the controller 15 determines the ideal number of steps of the stepping motor 17 according to the steering angle signal and the steering torque signal after analog-to-digital conversion as input signals; the controller 15 determines the actual number of steps of the stepping motor 17 according to the first pressure signal, the second pressure signal and the displacement amount signal after the analog-to-digital conversion as feedback signals; the controller 15 determines three parameters of the controller 15 based on the error between the desired step number and the actual step number of the stepper motor 17, and the error change rate, and finally determines the target step number of the stepper motor 17.
That is, an angle sensor 10 is installed under the steering wheel 9, which can accurately detect the rotation angle of the steering wheel 9, when the steering wheel 9 rotates, the steering torque and the steering angle are transmitted through a speed reducer mechanism 11 and then reach a force feedback motor 12, a control signal of the force feedback motor 12 enters a controller 15 through an a/D converter 16, the controller 15 outputs a digital signal and transmits the digital signal to a stepping motor 17 on a digital flow reversing valve 4, the stepping motor 17 drives a valve core to move, so as to realize the opening and closing and size control of a valve port of the digital flow reversing valve 4, and simultaneously, high-pressure oil pumped by a constant displacement pump 1 enters a steering cylinder through the valve port, wherein an overflow valve 3 plays a role of a safety valve, which ensures the steering pressure value of the whole hydraulic system, a constant pressure differential valve 2, which is a pressure compensation device, in order to make the differential pressure of the digital reversing flow valve constant, which ensures the steering speed to be stable, and simultaneously, the pressure loss of the pipeline can be reduced. At this time, the steering cylinder stretches to complete steering, the displacement sensor on the piston of the steering cylinder and the pressure sensor of the oil inlet and outlet of the steering cylinder detect the displacement of the piston and the system pressure in real time and feed back to the controller 15 after passing through the A/D converter 16, and at this time, an input signal of the steering wheel 9 is compared with a feedback signal of the steering cylinder, so that a closed-loop feedback system is formed, and high-precision steering control is realized.
The digital steer-by-wire system is suitable for an accurate operation environment, improves the use efficiency of a pump, reasonably distributes the power of an engine, reduces the energy consumption and improves the control skill of the wheel type engineering machinery; the digital steer-by-wire system occupies less space, the pipeline arrangement is simpler, the whole vehicle structure is more compact, the noise is low, the operation environment is optimized, the digital steer-by-wire system can form modularization, and the intelligent operation and unmanned driving are more easily realized.
Optionally, the method further comprises: and the constant pressure difference valve 2 is positioned between the inlet of the digital flow reversing valve 4 and the fixed displacement pump 1 and is used for compensating the pressure value of the inlet and the outlet of the digital flow reversing valve 4.
Optionally, the method further comprises: and the overflow valve 3 is connected in parallel at the inlet of the digital flow reversing valve 4 and used for preventing overflow.
It should be noted that three parameters of the controller 15 are automatically adjusted according to the external environment to ensure the stability of the control system. The controller 15 is a fuzzy adaptive PID controller 15, and the three parameters of the controller 15 are determined according to the following principle:
the controller 15 takes the error e and the change rate ec of the error as input, so as to meet the requirement of e and ec at different moments on the self-tuning of the PID parameters, and modifies the PID parameters on line by using a fuzzy control rule, so that the control system has good dynamic and static performances. The proportional, differential and integral parameters K can be established by utilizing fuzzy set theoryp、Ti、TdA binary continuous function relationship with the absolute value of error | e | and the absolute value of error variation | ec |:
Kp＝f1(|e|,|ec|)
Ti＝f2(|e|,|ec|)
Td＝f3(|e|,|ec|)
in general, the controlled process is applied to the parameter K under different | e | and | ec |p、Ti、TdThe self-tuning requirement can be summarized as follows:
1) when | e | is larger, a larger K should be used to make the system have a better fast tracking performancepWith a smaller TdMeanwhile, to avoid the system response from generating a large overshoot, the integral action is limited, and T is usually takeni＝O。
2) When | e | is at medium size, K is used to make the system response have small overshootpShould be made smaller, in which case TdThe value of (a) has a large influence on the system, TiThe value of (c) is to be taken as appropriate.
3) When | e | is small, K is used for better steady-state performance of the systempAnd TiShould be made larger, while T should be made larger to avoid oscillation of the system around the set pointdThe choice of value is of considerable importance.
As mentioned above, the controller 15 summarizes the technical knowledge and practical operation experience of the engineering designer, establishes a proper fuzzy rule table, and then obtains the respective setting Kp、Ti、TdFuzzy rules table of three parameters, and a fuzzy controller 15 for making inference and judgment. In addition, the controller 15 is established with K as follows for referencep、Ti、TdA fuzzy rule table.
And designing a fuzzy matrix table of PID parameters by using the membership of each fuzzy subset and a fuzzy control model of each parameter and applying fuzzy synthesis reasoning, and finding out correction parameters to be substituted into the following formula for calculation:
Kp＝Kp′+ΔKp
Ti＝Ti′+ΔTi
Td＝Td′+ΔTd
wherein K isp′、Ti′、TdThe' is the amount before correction, and in the online operation process, the system completes online self-correction of PID parameters through processing, table look-up and operation of fuzzy logic rules.
For example, if the ideal number of steps of the stepping motor 17 is 10 steps and the actual number of steps is 12 steps, the error is 2 steps, and the K of the controller 15 is smallpAnd TiShould be made larger, while T should be made larger to avoid oscillation of the system around the set pointdThe choice of the value is of considerable importance.
It should be noted that, an ideal step table of the stepping motor 17 corresponding to the steering angle of the steering wheel 9 and the steering torque of the steering wheel 9 is also prestored in the controller 15; the actual step number table of the stepping motor 17 corresponding to the first pressure signal, the second pressure signal and the displacement signal. The controller 15 can give the stepping motor 17 a target number of steps based on the aforementioned signals to more precisely control the opening size of the digital flow rate switching valve 4.
In summary, according to the digital steer-by-wire system provided by the embodiment of the present invention, the steering angle signal and the steering torque signal after the conversion by the a/D converter can be used as the input signal; the first pressure signal, the second pressure signal and the displacement signal after the conversion of the A/D converter are used as feedback signals; and the target step number of the stepping motor is determined according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve, so that a steering gear is omitted, the flow of a steering pump directly enters a steering cylinder, the use efficiency of the pump is improved, the power of an engine is reasonably distributed, the energy consumption is reduced, and the operation performance of the loader is improved.
Fig. 2 is a flowchart of a control method of a digital line steering system according to an embodiment of the present invention, as shown in fig. 2, including the following steps:
s1, acquiring a digitized steering angle signal and a digitized steering torque signal as input signals;
s2, acquiring the digitized first pressure signal, the digitized second pressure signal and the digitized displacement signal as feedback signals;
and S3, determining the target step number of the stepping motor according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve.
Alternatively, as shown in fig. 3, the step S3 of determining the target step number of the stepper motor according to the input signal and the feedback signal to determine the opening size of the digital flow direction valve includes:
s31, determining the ideal step number of the stepping motor according to the input signal;
s32, determining the actual step number of the stepping motor according to the feedback signal;
s33, obtaining the error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
s34, obtaining the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor according to the error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
s35, determining the target step number of the stepping motor based on the controller according to the error and the error change rate;
and S36, controlling the stepping motor according to the target step number of the stepping motor to determine the opening size of the digital flow reversing valve.
Alternatively, as shown in fig. 4, in step S35, determining the target number of steps of the stepping motor based on the controller according to the error and the error change rate includes:
fuzzifying the error and the error change rate, reasoning, calculating and analyzing by using a preset fuzzy rule, and carrying out parameter setting by automatically searching a fuzzy matrix table so as to meet the requirements of the error and the error change rate under different states on PID parameter self-setting and calculate three parameters K of the PIDp，Ti，TdThree parameters K according to PIDp，Ti，TdA target number of steps of the stepper motor is determined.
The target step number of the stepping motor can be dynamically updated through fuzzy self-adaptive PID adjustment, so that the whole system keeps better stability.
It should be noted that, three parameters of the controller should be automatically adjusted according to the external environment change, so as to ensure the stability of the control system. The controller is a fuzzy self-adaptive PID controller, and the three parameters of the controller are determined according to the following principle:
the controller takes the error e and the change rate ec of the error as input so as to meet the requirement of the e and the ec at different moments on the self-tuning of the PID parameters, and modifies the PID parameters on line by utilizing a fuzzy control rule so as to ensure that a control system has good dynamic and static performances. The proportional, differential and integral parameters K can be established by utilizing fuzzy set theoryp、Ti、TdBinary continuous function relationship with absolute value of error | e | and absolute value of rate of change of error | ec |:
Kp＝f1(|e|,|ec|)
Ti＝f2(|e|,|ec|)
Td＝f3(|e|,|ec|)
in general, the controlled process is applied to the parameter K under different | e | and | ec |p、Ti、TdThe self-tuning requirement can be summarized as follows:
1) when | e | is larger, a larger K should be used to make the system have a better fast tracking performancepWith a smaller TdMeanwhile, to avoid the system response from generating a large overshoot, the integral action is limited, and T is usually takeni＝O。
2) When | e | is at medium size, K is used to make the system response have small overshootpShould be made smaller, in which case TdThe value of (a) has a large influence on the system, TiThe value of (c) is to be taken as appropriate.
3) When | e | is small, K is used for better steady-state performance of the systempAnd TiShould be made larger, while T should be made larger to avoid oscillation of the system around the set pointdThe choice of the value is of considerable importance.
As mentioned above, the controller summarizes the technical knowledge and practical operation experience of the engineering designer, establishes a proper fuzzy rule table, and further obtains the respective setting Kp、Ti、TdFuzzy rule table of three parameters, so as to make inference and judgement. In addition, controlThe system is provided with K which is established as follows for referencep、Ti、TdA fuzzy rule table.
And designing a fuzzy matrix table of PID parameters by using the membership of each fuzzy subset and a fuzzy control model of each parameter and applying fuzzy synthesis reasoning, and finding out correction parameters to be substituted into the following formula for calculation:
Kp＝Kp′+ΔKp
Ti＝Ti′+ΔTi
Td＝Td′+ΔTd
wherein Kp′、Ti′、TdThe' is the amount before correction, and in the online operation process, the system completes online self-correction of PID parameters through processing, table look-up and operation of fuzzy logic rules.
For example, if the ideal number of steps of the stepping motor is 10 steps and the actual number of steps is 12 steps, the error is 2 steps, and the K of the controller is smallpAnd TiShould be made larger, while T should be made larger to avoid oscillation of the system around the set pointdThe choice of the value is of considerable importance.
It should be noted that, an ideal step table of the stepping motor corresponding to the steering angle of the steering wheel and the steering torque of the steering wheel is also prestored in the controller; the first pressure signal, the second pressure signal and the actual step number table of the stepping motor corresponding to the displacement signal. The controller can give the stepping motor a target number of steps according to the signals so as to more accurately control the opening size of the digital flow reversing valve.
Alternatively, the error between the ideal step number of the stepping motor and the actual step number of the stepping motor is obtained as a step number difference (e in fig. 5) between the ideal step number of the stepping motor and the actual step number of the stepping motor;
the error change rate of the ideal number of steps of the stepping motor and the actual number of steps of the stepping motor is obtained by differentiating the difference value of the number of steps (for example, ec in fig. 5).
In summary, according to the control method of the digital steer-by-wire system provided by the embodiment of the present invention, firstly, the digitized steering angle signal and the digitized steering torque signal are obtained as input signals; secondly, acquiring the first pressure signal, the second pressure signal and the displacement signal which are digitized as feedback signals; and finally, determining the target step number of the stepping motor according to the input signal and the feedback signal to determine the opening size of the digital flow reversing valve, so that a steering gear is omitted, the flow of a steering pump directly enters a steering cylinder, the service efficiency of the pump is improved, the power of an engine is reasonably distributed, the energy consumption is reduced, and the operating performance of the loader is improved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in some detail by the above embodiments, the invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the invention, and the scope of the invention is determined by the scope of the appended claims.
Claims (7)
1. A digital steerable system, comprising:
the control end of the digital flow reversing valve is connected with the stepping motor, one side port of the digital flow reversing valve is connected with the fixed displacement pump, and the other side port of the digital flow reversing valve is connected with a steering oil cylinder;
the angle sensor is used for acquiring a steering angle signal of a steering wheel;
the speed reducing mechanism is respectively connected with the angle sensor and the force feedback motor and is used for transmitting a steering torque signal of the steering wheel to the force feedback motor according to a steering angle signal acquired by the angle sensor;
one of the first pressure sensor and the second pressure sensor is used for acquiring a first pressure signal on an oil return path of the digital flow reversing valve, the other one of the first pressure sensor and the second pressure sensor is used for acquiring a second pressure signal on an oil outlet path of the digital flow reversing valve, and the displacement sensor is used for acquiring a piston expansion displacement signal of the steering oil cylinder;
the controller is used for taking the steering angle signal and the steering torque signal converted by the A/D converter as input signals; and the first pressure signal, the second pressure signal and the displacement amount signal after the conversion by the a/D converter are used as feedback signals; determining a target step number of the stepping motor according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve;
the determining a target number of steps of a stepper motor based on the input signal and the feedback signal to determine the opening size of the digital flow reversing valve comprises:
determining an ideal step number of the stepping motor according to the input signal;
determining the actual step number of the stepping motor according to the feedback signal;
acquiring an error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
acquiring the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor according to the error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
determining a target step number of the stepping motor based on a controller according to the error and the error change rate;
and controlling the stepping motor according to the target step number of the stepping motor so as to determine the opening size of the digital flow reversing valve.
2. The digital steer system of claim 1, further comprising: and the constant pressure difference valve is used for compensating the pressure value of the inlet and the outlet of the digital flow reversing valve.
3. The digital steer system of claim 1, further comprising: and the overflow valve is connected in parallel on an oil way at one side of the digital flow reversing valve, which is connected with the constant delivery pump, and is used for preventing overflow.
4. A control method of a digital line controlled steering system is characterized by comprising the following steps:
acquiring a digitized steering angle signal and a digitized steering torque signal as input signals;
acquiring a first digitized pressure signal, a second digitized pressure signal and a displacement signal as feedback signals;
determining a target step number of the stepping motor according to the input signal and the feedback signal so as to determine the opening size of the digital flow reversing valve;
the determining a target number of steps of a stepper motor based on the input signal and the feedback signal to determine the opening size of the digital flow reversing valve comprises:
determining the ideal step number of the stepping motor according to the input signal;
determining the actual step number of the stepping motor according to the feedback signal;
acquiring an error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
acquiring the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor according to the error between the ideal step number of the stepping motor and the actual step number of the stepping motor;
determining a target step number of the stepping motor based on a controller according to the error and the error change rate;
and controlling the stepping motor according to the target step number of the stepping motor so as to determine the opening size of the digital flow reversing valve.
5. The method of claim 4, wherein said determining a target number of steps of said stepper motor based on said error and a rate of change of error based on said controller comprises:
fuzzifying the error and the error change rate, performing reasoning, calculation and analysis by using a preset fuzzy rule, performing parameter setting by automatically searching a fuzzy matrix table to meet the requirement of the error and the error change rate in different states on PID parameter self-setting, and calculating three parameters K of the PIDp，Ti，TdAccording to three parameters K of said PIDp，Ti，TdDetermining a target number of steps of the stepper motor.
6. The method for controlling a digital steer-by-wire system according to claim 4, wherein said obtaining an error between an ideal number of steps of said stepper motor and an actual number of steps of said stepper motor is obtaining a difference between the ideal number of steps of said stepper motor and the actual number of steps of said stepper motor;
and the error change rate of the ideal step number of the stepping motor and the actual step number of the stepping motor is obtained by calculating the differential value of the step number difference.
7. An electronic device characterized by comprising the digital steer-by-wire system according to any one of claims 1 to 3.
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| JP6020881B2 (en) * | 2012-04-10 | 2016-11-02 | 株式会社ジェイテクト | Hydraulic power steering device |
| CN102806941B (en) * | 2012-08-02 | 2014-12-03 | 宁波海迈克动力科技有限公司 | High-precision forklift hydraulic steering system and control method thereof |
| CN104554432B (en) * | 2014-05-29 | 2017-04-12 | 四川大学 | Engineering machine steer-by-wire system |
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| CN105752152A (en) * | 2016-05-17 | 2016-07-13 | 山东汇川汽车部件有限公司 | Electric hydraulic power steering system for automobile |
| CN107600175B (en) * | 2017-10-09 | 2023-05-23 | 南京航空航天大学 | Active steering system of passenger car based on energy accumulator and steering control method thereof |
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| CN108820035B (en) * | 2018-05-29 | 2021-01-08 | 南京航空航天大学 | Steering control method of wire-controlled hydraulic steering system of commercial vehicle |
| CN209290484U (en) * | 2018-07-24 | 2019-08-23 | 王岚 | A kind of reversal valve electro-hydraulic steering device |
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