AU2020101128A4

AU2020101128A4 - Steering wheel steering gear and driving system, automatic driving system and method using steering gear

Info

Publication number: AU2020101128A4
Application number: AU2020101128A
Authority: AU
Inventors: Xiaowei PAN; Ruihao Wang; Hengshuai Zhang
Original assignee: JINAN KEYA ELECTRON SCIENCE AND TECHNOLOGY CO Ltd
Current assignee: JINAN KEYA ELECTRON SCIENCE AND TECHNOLOGY Co Ltd
Priority date: 2019-06-27
Filing date: 2020-06-25
Publication date: 2020-07-30
Anticipated expiration: 2028-06-25
Also published as: CN110203278A

Abstract

The present invention discloses a steering wheel steering gear and a driving system, an automatic driving system and method using the steering gear. A stator is fixedly mounted in a housing, a rotor is mounted at a positioning center, one end of the housing is sealed and provided with a circular mounting hole only in the center, an end cover is fixed to the other end of the housing, a center of the housing is also provided with a circular mounting hole, the stator comprises a mounting sleeve and a stator winding, the stator winding is arranged on an outer circumference of the mounting sleeve, the stator is mounted in the housing through the mounting sleeve, the rotor comprises a body, a first connecting sleeve is fixed to one end of the body, a second connecting sleeve is fixed to the other end of the body, a center of the body, the first connecting sleeve and the second connecting sleeve is provided with a rotating shaft mounting hole, and a rotor winding is arranged on an outer circumference of the body. The present invention is mainly used for driving of unmanned steering wheels in precise agricultural machinery. The steering wheel steering gear enables accurate positioning of agricultural machinery operations, can improve agricultural productivity, and can achieve fast, efficient, high-precision, and automated operations on large-area cultivated lands.

Description

STEERING WHEEL STEERING GEAR AND DRIVING SYSTEM, AUTOMATIC DRIVING SYSTEM AND METHOD USING STEERING GEAR

Field of the Invention The present invention relates to the technical field of automatic driving, and specifically to a steering wheel steering gear and a driving system, and an automatic driving system and method using the steering gear.

Background of the Invention With the continuous development of agricultural technology, the demand for agricultural automation has become more and more urgent in order to save labor and improve land utilization and labor efficiency. Agricultural automation operations are mainly implemented by automatic driving of agricultural machinery. During the automatic driving, an agricultural machinery driver needs to follow the whole journey, and needs to manually drive when reaching the edge of a field and encountering obstacles, so unmanned driving cannot be achieved, and more labor is still required.

Summary of the Invention The objective of the present invention is to provide a steering wheel steering gear and a driving system, an automatic driving system and method using the steering gear, to solve the problems raised in the background that an agricultural machinery driver needs to follow the whole journey, and needs to manually drive when reaching the edge of a field and encountering obstacles, so unmanned driving cannot be achieved, and more labor is still required. In order to achieve the above objective, the present invention provides the following technical solutions: A steering wheel steering gear includes a housing, an end cover, a rotor and a stator, the stator is fixedly mounted in the housing, the rotor is mounted at a positioning center, one end of the housing is sealed and provided with a circular mounting hole only in the center, the end cover is fixed to the other end of the housing, a center of the housing is also provided with a circular mounting hole, the stator includes a mounting sleeve and a stator winding, the stator winding is arranged on an outer circumference of the mounting sleeve, the stator is mounted in the housing through the mounting sleeve, the rotor includes a body, a first connecting sleeve is fixed to one end of the body, a second connecting sleeve is fixed to the other end of the body, a center of the body, the first connecting sleeve and the second connecting sleeve is provided with a rotating shaft mounting hole, a rotor winding is arranged on an outer circumference of the body, and the rotor is mounted in the housing through the first connecting sleeve and the second connecting sleeve. Further, a first bearing is mounted on the first connecting sleeve, a second bearing is mounted on the second connecting sleeve, and outer rings of the first bearing and the second bearing are both mounted within the housing. Further, the rotating shaft mounting hole is a cylindrical hole. Further, the second connecting sleeve extends out of the circular mounting hole at the sealed end of the housing. Further, the first connecting sleeve is arranged in the end cover. A driving system of the steering wheel steering gear is provided, the steering wheel steering gear has its own driving system, the driving system includes a control power supply and a driving power supply, and the control power supply supplies power to a CPU, a PWM, a protection circuit, a conditioning circuit, a resolver decoding circuit and a DA output respectively; the CPU controls the PWM, and the CPU is also connected with the protection circuit and the DA output; the driving power supply supplies power to a driving circuit and a current sensor respectively, the driving circuit is electrically connected to an inverter, the inverter is electrically connected to a PMSM, the current sensor is arranged between the inverter and the PMSM, the PMSM is electrically connected to a multi-turn absolute value encoder, the multi-turn absolute value encoder is electrically connected to the resolver decoding circuit, and the current sensor is electrically connected to the conditioning circuit. An automatic driving system using the steering gear includes a Beidou satellite base station receiver connected to a Beidou satellite and a main controller mounted on a vehicle, the Beidou satellite base station receiver is wirelessly connected to the main controller, the main controller includes a steering controller, a brake controller, an accelerator controller, a path comparison module and an obstacle detection controller, the steering controller is electrically connected to the steering wheel steering gear, the steering wheel steering gear is mounted on a rotating shaft of a steering wheel of the vehicle, an encoder is further mounted on the rotating shaft, the accelerator controller is electrically connected to an electronic accelerator of the vehicle, the brake controller is electrically connected to an electronic brake of the vehicle, the electronic accelerator and the electronic brake are both electrically connected to a speed sensor, the path comparison module is electrically connected to an angle calculation unit, the angle calculation unit is also electrically connected to the encoder, the encoder is electrically connected to the steering controller, and the obstacle detection controller includes a first radar and a second radar. Further, a fixed signal transmitter is arranged in the Beidou satellite base station receiver, a mobile signal receiver is arranged in the main controller, and the Beidou satellite base station receiver performs data transmission with the mobile signal receiver in the main controller through the fixed signal transmitter. Further, the encoder is electrically connected to a mobile signal transmitter, and the mobile signal transmitter is electrically connected to the main controller and the angle calculation unit. Further, the speed sensor is electrically connected to the main controller. Further, the angle calculation unit is electrically connected to the steering controller. Further, the first radar is mounted at a front end of a wheel of the vehicle, and the second radar is mounted at a front end of a head of the vehicle. An automatic driving method using the steering gear includes: step 1: the received Beidou navigation signal is captured, tracked, positioned and calculated by a Beidou satellite mobile station receiver to obtain a designated route for movement of the vehicle, and then a difference between the designated route and the data wirelessly transmitted from the Beidou satellite base station receiver is calculated to obtain an accurate position and attitude information of the vehicle itself; step 2: the designated route of the vehicle to be traveled is input into the main controller; the main controller obtains a position, speed, attitude information, and actual route of the vehicle from the mobile signal transmitter, and calculates a real time position of the vehicle through the information, and the path comparison module in the main controller compares the position with the designated route; step 3: the path comparison module obtains an angle a between the actual route and the designated route, the angle being an optimal angle at which the steering wheel steering gear needs to control the steering of the vehicle when the vehicle approaches the designated route; step 4: the steering controller obtains a current angle value 0 of the rotating shaft in the steering wheel steering gear in real time by reading the data of the encoder, wherein the angle a between the actual route and the designated route is known, and the rotating shaft in the steering wheel steering gear still needs to rotate an angle a-0, denoted by AO; step 5: the steering controller transmits, to the steering wheel steering gear, the angle AO that a guide wheel still needs to rotate, and the steering wheel steering gear drives the rotating shaft to rotate AO, such that an agricultural machine moves toward a specified direction; steps 3-5 are repeated, and the vehicle will gradually approach a desired path, and then follow the planned desired path, thereby achieving automatic driving control of the vehicle. Further, when the vehicle works normally, that is, when the vehicle is driven straight, the speed controller in the main controller controls the speed of the vehicle to less than 30 km/h by controlling the electronic accelerator, and the main controller monitors the speed through the speed sensor. Further, when the main controller detects that the vehicle needs to turn or turn around in the specified route, the speed controller in the main controller will reduce the speed of the vehicle to less than 10 km/h by controlling the electronic accelerator, and the main controller monitors the speed through the speed sensor. Further, when the first radar on the vehicle detects an obstacle signal and the second radar cannot detect the obstacle signal, the vehicle runs normally; when neither the first radar nor the second radar can detect an obstacle signal, the vehicle runs normally; when both the first radar and the second radar detect an obstacle signal, the obstacle detection controller feeds back the signal to the main controller, the brake controller in the main controller controls the electronic brake to brake the vehicle, and the main controller monitors the speed through the speed sensor. Compared with the prior art, the beneficial effects of the present invention are: the present invention is mainly used for driving of unmanned steering wheels in precise agricultural machinery. The steering wheel steering gear enables accurate positioning of agricultural machinery operations, can improve agricultural productivity, efficiently use agricultural resources and protect the ecological environment, is an effective way to achieve high-quality, high-yield, low-consumption, and environment friendly sustainable agriculture, can achieve fast, efficient, high-precision, and automated operations on large-area cultivated lands, and can be used for multiple production links such as leveling, sowing, harvesting, and pesticide spraying, which greatly improves production efficiency and land utilization.

Brief Description of the Drawings Fig. 1 is a three-dimensional structural diagram of a steering gear according to the present invention; Fig. 2 is a front-view structural diagram of Fig. 1 according to the present invention; Fig. 3 is an internal cross-sectional structural diagram of Fig. 1 according to the present invention; Fig. 4 is a three-dimensional structural diagram of a rotor in Fig. 3 according to the present invention; Fig. 5 is a front-view structural diagram of Fig. 4 according to the present invention; Fig. 6 is a cross-sectional structural diagram of a right view of Fig. 5 according to the present invention; Fig. 7 is a schematic structural diagram of a stator in Fig. 3 according to the present invention; Fig. 8 is a schematic diagram of an automatic driving system according to the present invention; Fig. 9 is a schematic diagram of formation of an angle a according to the present invention; Fig. 10 is a schematic diagram of installation of an obstacle detection controller in an automatic control system according to the present invention; Fig. 11 is a frame diagram of a driving system of the steering wheel steering gear according to the present invention; Fig. 12 is a schematic diagram of a multi-turn absolute encoder decoding circuit in the driving system according to the present invention; Fig. 13 is a schematic diagram of a conditioning circuit in the driving system according to the present invention; Fig. 14 is a schematic diagram of a protection circuit in the driving system according to the present invention; Fig. 15 is a schematic diagram of a DA conversion circuit in the driving system according to the present invention; Fig. 16 is a schematic diagram of a main power circuit in the driving system according to the present invention. In the figures: 1 housing, 2 end cover, 3 rotor, 301 body, 302 first connecting sleeve, 303 second connecting sleeve, 304 first bearing, 305 second bearing, 306 rotor winding, 307 rotating shaft mounting hole, 4 stator, 401 mounting sleeve, 402 stator winding, 403 power line, 5 Beidou satellite base station receiver, 6 main controller, 7 steering controller, 8 brake controller, 9 accelerator controller, 10 path comparison module, 11 obstacle detection controller, 12 steering wheel steering gear, 13 encoder, 14 mobile signal transmitter, 15 fixed signal transmitter, 16 mobile signal receiver, 17 electronic accelerator, 18 electronic brake, 19 speed sensor, 20 angle calculation unit, 21 first radar, 22 second radar.

Detailed Description of the Embodiments A clear and complete description will be made to the technical solutions in the embodiments of the present invention below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the embodiments described are only part of the embodiments of the present invention, not all of them. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present disclosure. Embodiment 1: Referring to Figs. 1-7, a steering wheel steering gear 12 includes a housing 1, an end cover 2, a rotor 3 and a stator 4, the stator 4 is fixedly mounted in the housing 1, the rotor 3 is mounted at a positioning center, one end of the housing 1 is sealed and provided with a circular mounting hole only in the center, the end cover 2 is fixed to the other end of the housing 1, a center of the housing 1 is also provided with a circular mounting hole, the stator 4 includes a mounting sleeve 401 and a stator winding 402, the stator winding 402 is arranged on an outer circumference of the mounting sleeve 401, the stator 4 is mounted in the housing 1 through the mounting sleeve 401, the rotor 3 includes a body 301, a first connecting sleeve 302 is fixed to one end of the body 301, a second connecting sleeve 303 is fixed to the other end of the body 301, a center of the body 301, thefirst connecting sleeve 302 and the second connecting sleeve 303 is provided with a rotating shaft mounting hole 307, a rotor winding 306 is arranged on an outer circumference of the body 301, and the rotor 3 is mounted in the housing 1 through the first connecting sleeve 302 and the second connecting sleeve 303. Embodiment 2:

Referring to Figs. 1-7, a steering wheel steering gear 12 includes a housing 1, an end cover 2, a rotor 3 and a stator 4, the stator 4 is fixedly mounted in the housing 1, the rotor 3 is mounted at a positioning center, one end of the housing 1 is sealed and provided with a circular mounting hole only in the center, the end cover 2 is fixed to the other end of the housing 1, a center of the housing 1 is also provided with a circular mounting hole, the stator 4 includes a mounting sleeve 401 and a stator winding 402, the stator winding 402 is arranged on an outer circumference of the mounting sleeve 401, the stator 4 is mounted in the housing 1 through the mounting sleeve 401, the rotor 3 includes a body 301, a first connecting sleeve 302 is fixed to one end of the body 301, a second connecting sleeve 303 is fixed to the other end of the body 301, a center of the body 301, the first connecting sleeve 302 and the second connecting sleeve 303 is provided with a rotating shaft mounting hole 307, a rotor winding 306 is arranged on an outer circumference of the body 301, and the rotor 3 is mounted in the housing 1 through the first connecting sleeve 302 and the second connecting sleeve 303. A first bearing 304 is mounted on the first connecting sleeve 302, a second bearing 305 is mounted on the second connecting sleeve 303, and outer rings of the first bearing 304 and the second bearing 305 are both mounted within the housing 1. The rotating shaft mounting hole 307 is a cylindrical hole. The second connecting sleeve 303 extends out of the circular mounting hole at the sealed end of the housing 1. The first connecting sleeve 302 is arranged in the end cover 2. The stator 4 is provided with a power line 403, and the stator 4 is electrically connected to a main controller through the power line 403. Control ports of the steering wheel steering gear include RS232, CAN, and analog voltage 0-5 V, and the housing of the steering wheel steering gear is provided with an external start-stop control button. Embodiment 3: On the basis of Embodiment 2, referring to Fig. 8, an automatic driving system using the steering gear includes a Beidou satellite base station receiver 5 connected to a Beidou satellite and a main controller 6 mounted on a vehicle, the Beidou satellite base station receiver 5 is wirelessly connected to the main controller 6, the main controller 6 includes a steering controller 7, a brake controller 8, an accelerator controller 9, a path comparison module 10 and an obstacle detection controller 11, the steering controller 7 is electrically connected to the steering wheel steering gear 12, the steering wheel steering gear 12 is mounted on a rotating shaft of a steering wheel of the vehicle, an encoder 13 is further mounted on the rotating shaft, the accelerator controller 9 is electrically connected to an electronic accelerator 17 of the vehicle, the brake controller 8 is electrically connected to an electronic brake 18 of the vehicle, the electronic accelerator 17 and the electronic brake 18 are both electrically connected to a speed sensor 19, the path comparison module 10 is electrically connected to an angle calculation unit 20, the angle calculation unit 20 is also electrically connected to the encoder 13, the encoder 13 is electrically connected to the steering controller 7, and the obstacle detection controller 11 includes a first radar 21 and a second radar 22. Embodiment 4: On the basis of Embodiment 2, referring to Fig. 8, an automatic driving system using the steering gear includes a Beidou satellite base station receiver 5 connected to a Beidou satellite and a main controller 6 mounted on a vehicle, the Beidou satellite base station receiver 5 is wirelessly connected to the main controller 6, the main controller 6 includes a steering controller 7, a brake controller 8, an accelerator controller 9, a path comparison module 10 and an obstacle detection controller 11, the steering controller 7 is electrically connected to the steering wheel steering gear 12, the steering wheel steering gear 12 is mounted on a rotating shaft of a steering wheel of the vehicle, an encoder 13 is further mounted on the rotating shaft, the accelerator controller 9 is electrically connected to an electronic accelerator 17 of the vehicle, the brake controller 8 is electrically connected to an electronic brake 18 of the vehicle, the electronic accelerator 17 and the electronic brake 18 are both electrically connected to a speed sensor 19, the path comparison module 10 is electrically connected to an angle calculation unit 20, the angle calculation unit 20 is also electrically connected to the encoder 13, the encoder 13 is electrically connected to the steering controller 7, and the obstacle detection controller 11 includes a first radar 21 and a second radar 22. A fixed signal transmitter 15 is arranged in the Beidou satellite base station receiver 5, a mobile signal receiver 16 is arranged in the main controller 6, and the Beidou satellite base station receiver 5 performs data transmission with the mobile signal receiver 16 in the main controller 6 through the fixed signal transmitter 15. The encoder 13 is electrically connected to a mobile signal transmitter 14, and the mobile signal transmitter 14 is electrically connected to the main controller 6 and the angle calculation unit 20. The speed sensor 19 is electrically connected to the main controller 6. The angle calculation unit 20 is electrically connected to the steering controller 7. The first radar 21 is mounted at a front end of a wheel of the vehicle, and the second radar 22 is mounted at a front end of a head of the vehicle. The encoder includes an incremental encoder and an absolute value sensor, the steering controller controls the working mode of the steering wheel steering gear in a speed mode and a position mode, and the steering controller is controlled by a CAN bus network, and realizes speed control and data reading of the steering wheel steering gear through RS232. Configuration table of working mode: Working mode Control instruction Feedback element RS232 CAN Incremental encoder, Speed mode Analog voltage 0-5 V absolute value sensor RS232 CAN Incremental encoder, Position mode Analog voltage 0-5 V absolute value sensor Embodiment 5: On the basis of Embodiment 4, referring to Figs. 8-10, an automatic driving method using the steering gear includes steps 1 to 5 includes the following steps. Step 1: the received Beidou navigation signal is captured, tracked, positioned and calculated by a Beidou satellite mobile station receiver to obtain a designated route for movement of the vehicle, and then a difference between the designated route and the data wirelessly transmitted from the Beidou satellite base station receiver 5 is calculated to obtain an accurate position and attitude information of the vehicle itself; Step 2: the designated route of the vehicle to be traveled is input into the main controller 6. The main controller 6 obtains a position, speed, attitude information, and actual route of the vehicle from the mobile signal transmitter 14, and calculates a real time position of the vehicle through the information, and the path comparison module in the main controller 6 compares the position with the designated route; Step 3: the path comparison module 10 obtains an angle a between the actual route and the designated route, the angle being an optimal angle at which the steering wheel steering gear 12 needs to control the steering of the vehicle when the vehicle approaches the designated route; Step 4: the steering controller 7 obtains a current angle value 0 of the rotating shaft in the steering wheel steering gear 12 in real time by reading the data of the encoder 13, wherein the angle a between the actual route and the designated route is known, and the rotating shaft in the steering wheel steering gear 12 still needs to rotate an angle a , denoted by AO; Step 5: the steering controller 7 transmits, to the steering wheel steering gear 12, the angle AO that a guide wheel still needs to rotate, and the steering wheel steering gear 12 drives the rotating shaft to rotate A, such that an agricultural machine moves toward a specified direction; Steps 3-5 are repeated, and the vehicle will gradually approach a desired path, and then follow the planned desired path, thereby achieving automatic driving control of the vehicle. Embodiment 6: On the basis of Embodiment 4, referring to Figs. 8-10, an automatic driving method using the steering gear includes steps 1 to 5 includes the following steps. Step 1: the received Beidou navigation signal is captured, tracked, positioned and calculated by a Beidou satellite mobile station receiver to obtain a designated route for movement of the vehicle, and then a difference between the designated route and the data wirelessly transmitted from the Beidou satellite base station receiver 5 is calculated to obtain an accurate position and attitude information of the vehicle itself; Step 2: the designated route of the vehicle to be traveled is input into the main controller 6. The main controller 6 obtains a position, speed, attitude information, and actual route of the vehicle from the mobile signal transmitter 14, and calculates a real time position of the vehicle through the information, and the path comparison module in the main controller 6 compares the position with the designated route; Step 3: the path comparison module 10 obtains an angle a between the actual route and the designated route, the angle being an optimal angle at which the steering wheel steering gear 12 needs to control the steering of the vehicle when the vehicle approaches the designated route; Step 4: the steering controller 7 obtains a current angle value 0 of the rotating shaft in the steering wheel steering gear 12 in real time by reading the data of the encoder 13, wherein the angle a between the actual route and the designated route is known, and the rotating shaft in the steering wheel steering gear 12 still needs to rotate an angle a , denoted by A; Step 5: the steering controller 7 transmits, to the steering wheel steering gear 12, the angle AO that a guide wheel still needs to rotate, and the steering wheel steering gear

12 drives the rotating shaft to rotate AO, such that an agricultural machine moves toward a specified direction; Steps 3-5 are repeated, and the vehicle will gradually approach a desired path, and then follow the planned desired path, thereby achieving automatic driving control of the vehicle. When the vehicle works normally, that is, when the vehicle is driven straight, the speed controller in the main controller 6 controls the speed of the vehicle to less than km/h by controlling the electronic accelerator 17, and the main controller 6 monitors the speed through the speed sensor 19. When the main controller 6 detects that the vehicle needs to turn or turn around in the specified route, the speed controller in the main controller 6 will reduce the speed of the vehicle to less than 10 km/h by controlling the electronic accelerator 17, and the main controller 6 monitors the speed through the speed sensor 19. When the first radar 21 on the vehicle detects an obstacle signal and the second radar 22 cannot detect the obstacle signal, the vehicle runs normally; when neither the first radar 21 nor the second radar 22 can detect an obstacle signal, the vehicle runs normally; when both the first radar 21 and the second radar 22 detect an obstacle signal, the obstacle detection controller 11 feeds back the signal to the main controller 6, the brake controller 8 in the main controller 6 controls the electronic brake 18 to brake the vehicle, and the main controller 6 monitors the speed through the speed sensor 19. The steering wheel steering gear has its own driving system, the driving system includes a control power supply and a driving power supply, and the control power supply supplies power to a CPU, a PWM, a protection circuit, a conditioning circuit, a resolver decoding circuit and a DA output respectively; the CPU controls the PWM, and the CPU is also connected with the protection circuit and the DA output; the driving power supply supplies power to a driving circuit and a current sensor respectively, the driving circuit is electrically connected to an inverter, the inverter is electrically connected to a PMSM, the current sensor is arranged between the inverter and the PMSM, the PMSM is electrically connected to a multi-turn absolute value encoder, the multi-turn absolute value encoder is electrically connected to the resolver decoding circuit, the current sensor is electrically connected to the conditioning circuit, and the CPU adopts digital control with a computing core DSPTMS320F28335, and is designed with a multi-turn absolute value encoder decoding circuit, a sampling conditioning circuit, a protection circuit, a DA output display circuit, etc.; and a main power circuit uses MOSFET as a switching device for the inverter. As shown in Fig. 12, in the multi-turn absolute value encoder decoding circuit, a multi-turn absolute value encoder is used as an angular displacement sensor of the steering wheel steering gear. Compared with a photoelectric encoder, the multi-turn absolute value encoder is more suitable for environments with large vibration, and has advantages in direct driving systems for special occasions such as machine tools. The multi-turn absolute value encoder has a maximum angle measurement error 10+, uses a sine wave differential signal with a frequency of 10 kHz as an excitation input, has an output waveform amplitude varying with the angle, and achieves digital reading of an angular velocity signal by means of a multi-turn absolute value decoding chip for digital decoding. A II type closed-loop system is used in the multi-turn absolute value decoding chip, with a maximum 16-bit angle decoding precision and a signed 15-bit speed decoding precision. The chip is used in this system to design the resolver decoding circuit. The circuit mainly includes a clock circuit, an excitation signal conditioning circuit, a sine and cosine signal filter circuit, etc. This system uses a 8.192 MHz passive crystal oscillator as a clock signal, and the excitation signal conditioning circuit needs to be designed according to the range of voltage transmitted and received by the decoding chip. The chip can send an excitation signal of 3.6Vp-p10% and receive a resolver feedback signal of 3.15Vp-p20%. Levels of RESO and RESI pins determine the decoding resolution of the chip. If the decoding resolution is higher, the angular velocity range that can be resolved is smaller. This system has a highest 16-bit resolution, so both the RESO and RES1 pins are connected to a high level. At this resolution, the decoding chip can track up to 7500 r/min, greater than a default excitation frequency 10 kHz of a maximum speed chip of an experimental motor, which is the same as the requirement for the excitation frequency of the multi-turn absolute value encoder used. A rail-to-rail operational amplifier TS922A is used to construct the excitation signal conditioning circuit for amplitude adjustment and filter processing, which not only enhances the driving ability of the excitation signal, but also reduces the noise of the excitation signal. The chip supports serial and parallel data communication manners. The SOE pin is a serial communication enable pin, and is valid at a low level. If data is transmitted in a parallel manner, the SOE pin should be connected to a high level. Levels of AO and

Al pins determine an operating mode of the chip. When AO and Al are both at a low level, a decoded angle digital signal will be output. When AO is at a low level and Al is at a high level, an angular velocity digital signal will be output. This system adopts a serial transmission manner, and controls the level change of the Al pin through a GPIO port of a DSP to switch the output mode of angle and angular velocity signals of the decoding chip. When the conditioning circuit of the multi-turn absolute value decoding chip is designed, it should pay attention to the phase locking range of sines and cosines, that is, the phase difference between the EXC output and the sine and cosine input cannot exceed 440. Due to the filter processing on the EXC output and SIN and COS input pins of the chip, the phase shift at 10 kHz needs to be taken into account when the filter circuit is designed, to ensure that the phase shift of the conditioning circuit of the entire multi-turn absolute value decoding chip is within 44°. TMS320F28335 provides an AD conversion channel of dual 8-channel 12-bit resolution, which requires an input voltage range of 0 to 3 V. The conditioning circuit performs amplitude adjustment and filter processing on output signals of current and voltage sensors to meet the input level requirements of the AD conversion channel of the DSP. The present invention takes an A-phase current conditioning circuit as an example to clarify the design idea of the conditioning circuit of this system. Fig. 13 shows an A-phase current conditioning circuit, which is formed by cascading two cascaded operational amplifier circuits. The front operational amplifier A plays a role in adjusting the bias and amplitude of an output signal XI a of the current sensor, such that the output level is between 0 and 3 V; and the back operational amplifier B constructs an active second-order filter circuit to reduce the influence of sampling noise and improve the reliability of current sampling. The current sensor used by the system outputs a bipolar current signal XI a, which should be converted into a bipolar voltage signal by a grounding resistor, with a voltage range of -3 V to +3 V. Accordingly, the bipolar voltage signal needs to be further processed to reduce its level change range to within 0 to 3 V. The circuit adjusts the bias and amplitude of the bipolar voltage signal by adding a reference voltage. The adjustment formula is:

X, = XI2 , where XIa is an output signal of the current sensor;

Vref is a 3 V bias voltage constructed by a voltage regulator chip TL431; XIa' is an output of the operational amplifier A. The level range of the adjusted voltage signal

XIa' is 0 to 3 V, which just meets the input voltage requirement of the AD conversion channel. As shown in Fig. 14, the protection circuit has the functions of bus overcurrent protection, bus overvoltage protection, resolver decoding fault protection, software error protection, etc. When the protection circuit receives any of the protection signals, the system will immediately block the output of a drive signal. The ErrO signal of the protection circuit is a DC bus overcurrent protection signal. The present invention only takes the overcurrent protection as an example to illustrate the working process of the protection circuit. XI DC is a voltage corresponding to the conditioned DC bus current, and a negative input terminal of a voltage comparator LM393 has a set bus overcurrent voltage threshold. If the XI DC exceeds the voltage threshold, an overcurrent protection signal lamp will light up, the ErrO level will change from high to low, a D flip-flop CD4013B is triggered by a rising edge, the level of an output pin flips, a system error signal lamp lights up, and a FAULT signal is changed to have a high level, thereby triggering a CPLD to block the drive output signal. Because trigger source signals of the protection circuit are analog signals, and an NAND gate and the D flip-flop used in a logic circuit are digital chips, an optocoupler is required to isolate the trigger source signal from a logic level, and the optocoupler also realizes the function of level conversion. As shown in Fig. 15, a DA conversion circuit plays a role in outputting a variable in a digital control system as an analog voltage, so as to facilitate the display and analysis of an oscilloscope. The specific process is: a digital variable in a program is first transmitted to the DA conversion circuit in a parallel or serial manner, then the DA conversion circuit converts the digital variable into an analog voltage signal, and the waveform of the analog voltage is viewed through the oscilloscope. The DA conversion circuit is built in this system by using an 8-channel 13-bit parallel DA chip MAX547 of Maxim Integrated. The DA chip is powered by dual power supplies, and a -5 V voltage regulator source built by means of TL431 is used as a negative voltage source of MAX547; the reference voltage of the DA chip is provided by ADR4525, and a follower circuit is formed using MAX494 to improve the driving capability of the reference voltage chip; AO-A2 pins are connected to DSP address pins XA-XA2 to select a data output channel. A three-phase bridge structure is used in the main power circuit to design a voltage source type inverter, and switching devices are six power field effect transistors of model IXFH52N300. MOSFET has the advantages of small on-resistance, small drive current, fast on-speed, etc., and can reduce the heat loss of a power amplifier circuit in an occasion of high switching frequency. The principle diagram of the main power circuit is as shown in Fig. 16. Drive signals for MOSFET are generated by an IR2110 chip, and three paths of signals output by the power transistors are respectively connected to U, V, and W three-phase winding terminals of a permanent magnet synchronous motor. The internal output impedance of the IR2110 chip is low, and if the internal output impedance is directly used to drive the power devices, voltage oscillation between the drain and source of the MOSFET will be caused, so a resistor is connected in series to an output terminal of the IR2110 to improve the stability of drive. At the same time, a diode is connected in anti-parallel to the series resistor to improve the tum-off speed. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments are considered as illustrative but not restrictive at any point, and the scope of the present invention is defined by the appended claims instead of the above description. Accordingly, all variations fall within the meanings and scope of equivalent elements of the claims are intended to be included in the present invention. Any reference signs in the claims should not be construed as limiting the claims.

Claims

Claims 1. A steering wheel steering gear, comprising a housing, an end cover, a rotor and a stator, the stator is fixedly mounted in the housing, the rotor is mounted at a positioning center, one end of the housing is sealed and provided with a circular mounting hole only in the center, the end cover is fixed to the other end of the housing, a center of the housing is also provided with a circular mounting hole, the stator includes a mounting sleeve and a stator winding, the stator winding is arranged on an outer circumference of the mounting sleeve, the stator is mounted in the housing through the mounting sleeve, the rotor includes a body, a first connecting sleeve is fixed to one end of the body, a second connecting sleeve is fixed to the other end of the body, a center of the body, the first connecting sleeve and the second connecting sleeve is provided with a rotating shaft mounting hole, a rotor winding is arranged on an outer circumference of the body, and the rotor is mounted in the housing through the first connecting sleeve and the second connecting sleeve.
2. The steering wheel steering gear according to claim 1, wherein a first bearing is mounted on the first connecting sleeve, a second bearing is mounted on the second connecting sleeve, and outer rings of the first bearing and the second bearing are both mounted within the housing.
3. A driving system of the steering wheel steering gear according to any one of claims 1-2, wherein the steering wheel steering gear has its own driving system, the driving system includes a control power supply and a driving power supply, and the control power supply supplies power to a CPU, a PWM, a protection circuit, a conditioning circuit, a resolver decoding circuit and a DA output respectively; the CPU controls the PWM, and the CPU is also connected with the protection circuit and the DA output; the driving power supply supplies power to a driving circuit and a current sensor respectively, the driving circuit is electrically connected to an inverter, the inverter is electrically connected to a PMSM, the current sensor is arranged between the inverter and the PMSM, the PMSM is electrically connected to a multi-turn absolute value encoder, the multi-turn absolute value encoder is electrically connected to the resolver decoding circuit, and the current sensor is electrically connected to the conditioning circuit.
4. An automatic driving system using the steering wheel steering gear according to any one of claims 1-2, comprising a Beidou satellite base station receiver connected to a Beidou satellite and a main controller mounted on a vehicle, the Beidou satellite base station receiver is wirelessly connected to the main controller, the main controller includes a steering controller, a brake controller, an accelerator controller, a path comparison module and an obstacle detection controller, the steering controller is electrically connected to the steering wheel steering gear, the steering wheel steering gear is mounted on a rotating shaft of a steering wheel of the vehicle, an encoder is further mounted on the rotating shaft, the accelerator controller is electrically connected to an electronic accelerator of the vehicle, the brake controller is electrically connected to an electronic brake of the vehicle, the electronic accelerator and the electronic brake are both electrically connected to a speed sensor, the path comparison module is electrically connected to an angle calculation unit, the angle calculation unit is also electrically connected to the encoder, the encoder is electrically connected to the steering controller, and the obstacle detection controller includes a first radar and a second radar.
5. The automatic driving system according to claim 3, wherein a fixed signal transmitter is arranged in the Beidou satellite base station receiver, a mobile signal receiver is arranged in the main controller, and the Beidou satellite base station receiver performs data transmission with the mobile signal receiver in the main controller through the fixed signal transmitter.
6. The automatic driving system according to claim 3, wherein the encoder is electrically connected to a mobile signal transmitter, and the mobile signal transmitter is electrically connected to the main controller and the angle calculation unit.
7. The automatic driving system according to claim 3, wherein the speed sensor is electrically connected to the main controller.
8. The automatic driving system according to claim 3, wherein the angle calculation unit is electrically connected to the steering controller.
9. The automatic driving system according to claim 3, wherein the first radar is mounted at a front end of a wheel of the vehicle, and the second radar is mounted at a front end of a head of the vehicle.
10. An automatic driving method using the steering gear according to any one of claims 1-2, wherein step 1: the received Beidou navigation signal is captured, tracked, positioned and calculated by a Beidou satellite mobile station receiver to obtain a designated route for movement of the vehicle, and then a difference between the designated route and the data wirelessly transmitted from the Beidou satellite base station receiver is calculated to obtain an accurate position and attitude information of the vehicle itself; step 2: the designated route of the vehicle to be traveled is input into the main controller; the main controller obtains a position, speed, attitude information, and actual route of the vehicle from the mobile signal transmitter, and calculates a real time position of the vehicle through the information, and the path comparison module in the main controller compares the position with the designated route; step 3: the path comparison module obtains an angle a between the actual route and the designated route, the angle being an optimal angle at which the steering wheel steering gear needs to control the steering of the vehicle when the vehicle approaches the designated route; step 4: the steering controller obtains a current angle value 0 of the rotating shaft in the steering wheel steering gear in real time by reading the data of the encoder, wherein the angle a between the actual route and the designated route is known, and the rotating shaft in the steering wheel steering gear still needs to rotate an angle a-0, denoted by AO; step 5: the steering controller transmits, to the steering wheel steering gear, the angle AO that a guide wheel still needs to rotate, and the steering wheel steering gear drives the rotating shaft to rotate AG, such that an agricultural machine moves toward a specified direction; steps 3-5 are repeated, and the vehicle will gradually approach a desired path, and then follow the planned desired path, thereby achieving automatic driving control of the vehicle.