CN108382456A - A kind of pilotless automobile electric wire-control transfer and rotating direction control method - Google Patents

Abstract

The invention discloses an electric control-by-wire steering device for an unmanned vehicle, comprising: a steering motor; a spur gear reducer, which is connected to the output shaft of the steering motor through a driving gear; a bevel gear reducer, which is driven through a conical The gear is connected with the output shaft of the spur gear reducer; the steering transmission shaft, one end of which passes through the bevel gear reducer and is connected with the driven gear of the bevel gear reducer. The electric steering-by-wire steering device for an unmanned vehicle provided by the present invention adopts an electric motor to provide power, occupies a small space, has strong versatility, and has a large torque, and can realize precise steering control. The steering control method of the driverless car based on the electric control-by-wire steering device of the driverless car provided by the present invention controls the rotation angle of the steering drive shaft through the fuzzy control method during the driving process of the vehicle, so that the steering control of the vehicle is more accurate. accurate.

Description

An electric control-by-wire steering device and steering control method for an unmanned vehicle

technical field

The invention belongs to the technical field of unmanned vehicle control, and in particular relates to an electric control-by-wire steering device and a steering control method for an unmanned vehicle.

Background technique

Unmanned vehicles are one of the future development directions of automobiles. It is expected that unmanned vehicles will become a safe means of transportation in people's lives in the future. Therefore, the intelligent vehicle driving system has also attracted much attention in the field of vehicle technology. Unmanned vehicles integrate many technologies such as automatic control, architecture, artificial intelligence, and visual computing. They are products of highly developed computer science, pattern recognition, and intelligent control technologies, and are an important indicator of a country's scientific research strength and industrial level. . In dangerous and harsh environments such as military, exploration and rescue, unmanned vehicles have broad application prospects, such as the current exploration of Mars rovers in the United States on Mars; in civilian use, it also has broad application prospects and a huge market. Because of its reliable, safe, convenient and efficient performance advantages, it has great practical significance for improving the intelligence and safety of human driving, and in the future, driverless cars can be networked with urban traffic command centers to choose the best route , effectively avoid traffic jams, and try our best to ensure the smooth flow of traffic. For example, in the United States, unmanned vehicles have begun to be put into the civilian market. For example, the self-driving vehicle launched by Google not long ago has passed the law in California and will soon be put into the market. For the 2010 Shanghai World Expo, visitors only need to press a button at the entrance of the park, and a four-seater convertible car without a driver will come from a distance and stop slowly, and then carry passengers to the attractions they want to visit. Therefore, many countries in the world are currently vigorously researching unmanned driving technology, using unmanned driving as an important platform to demonstrate their artificial intelligence level and lead the future development of vehicles.

In unmanned driving and intelligent driving, the steering system of the car is required to have the function of automatic steering, which requires a steering motor installed in the steering system of the car, so as to realize the wire control of the steering of the car, and complete the needs of automatic driving and intelligent driving. However, hydraulic power steering is mostly used in most models now. Even if electric power steering is used, the torque of the steering motor cannot complete the steering action of the car.

Contents of the invention

The object of the present invention is to provide a steer-by-wire device powered by an electric motor, through which the steer-by-wire control of the steering system during unmanned or intelligent driving can be realized, thereby realizing precise steering control.

Another object of the present invention is to provide a steering control method for an unmanned vehicle based on the electric control-by-wire steering device of an unmanned vehicle. The rotation angle of the steering drive shaft is controlled by the method of fuzzy control during the driving process of the vehicle, so that Steering control of the vehicle is more precise.

The technical scheme provided by the invention is:

An electric steering-by-wire device for an unmanned vehicle, comprising:

steering motor;

A spur gear reduction box, which is connected with the output shaft of the steering motor through a driving gear;

A bevel gear reducer, which is connected with the output shaft of the spur gear reducer through a bevel drive gear;

One end of the steering transmission shaft passes through the bevel gear reducer and is connected with the driven gear of the bevel gear reducer.

Preferably, the steering motor is vertically arranged with the steering transmission shaft.

Preferably, the steering motor is fixedly installed on the bevel gear reducer.

Preferably, the reduction ratio of the spur gear reducer is 2:1.

Preferably, the driving gear of the spur gear reducer is connected with the output shaft of the steering motor through a flat key.

Preferably, the driven gear of the spur gear reducer is connected with the output shaft of the spur gear reducer through a flat key.

Preferably, the input shaft and the output shaft of the spur gear reducer are connected to the casing of the spur gear reducer through bearings.

A steering control method for an unmanned vehicle, using the electric control-by-wire steering device for an unmanned vehicle, comprising:

Transform the angle α between the tangent of the vehicle's planned turning path and the central axis of the vehicle body, the vehicle speed V, and the rotation angle θ of the steering drive shaft into quantified levels in the fuzzy domain;

The angle α between the tangent of the planned turning path of the vehicle and the central axis of the vehicle body and the vehicle speed V are input into the fuzzy control model, and the angle α between the tangent of the planned turning path of the vehicle and the central axis of the vehicle body in the fuzzy control model is divided into 7 grades, divide the vehicle speed V into 7 grades;

The output of the fuzzy control model is the rotation angle θ of the steering transmission shaft, which is divided into 7 levels; according to the rotation angle θ of the steering transmission shaft, the steering of the vehicle is controlled.

Preferably, the domain of discourse of the included angle α between the tangent of the planned turning path of the vehicle and the central axis of the vehicle body is [-90,90], the domain of discourse of the vehicle speed V is [0,120], and the quantization factors are all set to 1, and the steering The rotation angle θ of the transmission shaft is [-900, 900].

Preferably, the transmission shaft rotation angle θ is corrected according to the friction coefficient μ of the road surface, the vehicle weight M, the vehicle body length L and the vehicle body width W, and the corrected transmission shaft rotation angle is:

where e is the base of the natural logarithm.

The beneficial effects of the present invention are:

(1) The electric steering-by-wire steering device for unmanned vehicles provided by the present invention uses an electric motor to provide power, which can realize wire-by-wire control of the steering system during unmanned driving or intelligent driving.

(2) The electric steering-by-wire steering device for an unmanned vehicle provided by the present invention occupies a small space, has strong versatility, and has a large torque, and can realize precise steering control.

(3) The steering control method of an unmanned vehicle based on the electric control-by-wire steering device of an unmanned vehicle provided by the present invention controls the rotation angle of the steering drive shaft during the running of the vehicle through a fuzzy control method to make the steering of the vehicle Control is more precise.

Description of drawings

FIG. 1 is a schematic diagram of the overall structure of the electric steering-by-wire device for an unmanned vehicle according to the present invention.

Fig. 2 is a schematic diagram of the installation of the steering motor and the spur gear reducer according to the present invention.

Fig. 3 is a structural schematic diagram of the spur gear reduction box according to the present invention.

Fig. 4 is the membership function of the included angle α between the tangent of the planned turning path of the vehicle and the central axis of the vehicle body according to the present invention.

Fig. 5 is the membership function of the vehicle speed V according to the present invention.

Fig. 6 is the membership function of the rotation angle θ of the steering transmission shaft according to the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings, so that those skilled in the art can implement it with reference to the description.

As shown in Figures 1-3, the present invention provides an electric steering-by-wire device for unmanned vehicles, which includes a steering motor 110; the output end of the steering motor 110 is connected to a spur gearbox 120, and through the direct The gear reduction box 120 outputs torque. Wherein, the end surface of the steering motor 110 is fixedly connected to the case cover 124 of the spur gear reduction case 120 by bolts. The input shaft and the output shaft of the spur gear reducer 120 are respectively connected to the casing of the spur gear reducer 120 through bearings. The driving gear 121 of the spur gear reduction box 120 is connected with the output shaft of the steering motor 110 through a flat key, and the driving gear 121 is meshed with the driven gear 122 of the spur gear reduction box 120 for transmission. The driven gear 122 is connected with the output shaft of the spur gear reduction box 120 through a flat key. The reduction ratio of the spur gear reducer 120 is 2:1. Wherein, the driving gear 121 and the driven gear 122 are connected with the gear case cover 124 through bearings.

The bevel gear reducer 130 includes a bevel driving gear and a bevel driven gear, the axes of the bevel drive gear and the bevel driven gear are perpendicular to each other. The bevel gear reducer 130 is connected to the output shaft of the spur gear reducer through a bevel drive gear, and the bevel drive gear is meshed with the bevel driven gear of the bevel gear reducer. Steering transmission shaft 140 , which is vertically arranged with the steering motor 110 , one end of the steering transmission shaft 140 passes through the bevel gear reducer 130 and is fixedly connected with the bevel driven gear of the bevel gear reducer 130 . Torque is transmitted from the output shaft of the linear gearbox to the bevel driven gear through the bevel driving gear, and then to the steering transmission shaft 140 .

The electric steering-by-wire device for unmanned vehicles also includes a steering transmission shaft fixing bracket 150, which is fixedly installed on the vehicle frame, and the steering transmission shaft 140 passes through the fixing bracket and is rotatably supported on the steering shaft. On the transmission shaft fixing frame 150 , the steering transmission shaft fixing frame 150 is used for supporting and positioning the steering transmission shaft 140 .

When the car needs to turn, the steering motor works to provide steering power. After deceleration and torque increase by the spur gear reduction mechanism, the power is transmitted to the bevel gear reduction mechanism. After deceleration and torque increase again, the power is transmitted to the steering drive shaft. The steering function of the car.

The present invention also provides a steering control method for an unmanned vehicle using the electric control-by-wire steering device for an unmanned vehicle. During the steering process of the vehicle, a fuzzy control method is used to output the angle θ that the transmission shaft needs to turn. , and finally calculate the rotation angle of the steering motor through the reduction ratio of the reduction mechanism, and control the rotation of the steering motor through the controller, so as to achieve the purpose of precisely controlling the turning of the unmanned vehicle.

The input of the fuzzy controller is the angle α between the tangent of the planned turning path of the vehicle and the central axis of the vehicle body and the vehicle speed V, and the output is the rotation angle θ of the steering drive shaft; The variation range of the angle α is [-90,90], the variation range of the vehicle speed V is [0,120], and the quantization factor is set to 1. Therefore, its domains are [-90,90] and [0,120] respectively, and the steering transmission The rotation angle θ of the shaft is [-900, 900]. Among them, the positive and negative values in the range of the angle α between the tangent line of the planned turning path of the vehicle and the central axis of the vehicle body and the rotation angle θ of the steering drive shaft represent different directions of rotation, and the absolute values of α and θ represent the angle. In order to ensure the accuracy of the control, so that it can be well controlled under various working conditions, according to repeated tests, the range of the angle α between the tangent of the vehicle's planned turning path and the central axis of the vehicle body is finally divided into 7 levels, fuzzy The set is {NB, NM, NS, 0, PS, PM, PB}; the vehicle speed V range is divided into 7 levels, and the fuzzy set is {0, PS, PM, PB, PVB, PMB, PBB}; the output corner The range of θ is divided into 7 grades, namely {NB, NM, NS, 0, PS, PM, PB}; the membership functions are triangular membership functions, as shown in Figures 4, 5 and 6.

The selection experience of the fuzzy control rule is: when the angle α between the tangent of the vehicle’s planned turning path and the central axis of the vehicle body is positive, the rotation angle θ of the steering drive shaft is positive. At this time, when the value of input α is large and the value of vehicle speed V is large , the rotation angle θ of the output steering transmission shaft is large; when the angle α between the tangent of the vehicle’s planned turning path and the central axis of the vehicle body is negative, the rotation angle θ of the steering transmission shaft is negative. At this time, when the absolute value of the input α is large, And when the value of the vehicle speed V is large, the absolute value of the rotation angle θ of the output steering drive shaft is large. The specific fuzzy control rules are shown in Table 1:

Table 1 Fuzzy control rules

In another embodiment, the steering control method of an unmanned vehicle further includes: according to the friction coefficient of the road surface, the vehicle weight (the real-time weight of the vehicle monitored by the weight sensor, including the self-weight and load of the vehicle body), the length of the vehicle body and the width of the vehicle body , correct the transmission shaft angle θ output by the fuzzy control model, so that the angle control of the steering transmission shaft is more accurate, and the corrected transmission shaft angle is:

Among them, e is the base number of natural logarithm; μ is the road surface friction coefficient; M is the weight of the vehicle, in Kg; L is the length of the vehicle body, in m; W is the width of the vehicle body, in m.

The electric steering-by-wire steering device for an unmanned vehicle provided by the present invention adopts an electric motor to provide power, occupies a small space, has strong versatility, and has a large torque, and can realize precise steering control. The steering control method of the driverless car based on the electric control-by-wire steering device of the driverless car provided by the present invention controls the rotation angle of the steering transmission shaft through the fuzzy control method during the driving process of the vehicle, so that the steering control of the vehicle is more accurate. accurate.

Although the embodiment of the present invention has been disclosed as above, it is not limited to the use listed in the specification and implementation, it can be applied to various fields suitable for the present invention, and it can be easily understood by those skilled in the art Therefore, the invention is not limited to the specific details and examples shown and described herein without departing from the general concept defined by the claims and their equivalents.

Claims (10)

1. a kind of pilotless automobile electric wire-control transfer, which is characterized in that including：

Steering motor；

Spur gear reduction box passes through the output axis connection of driving gear and the steering motor；

Conic reducer passes through the output axis connection of taper driving gear and the spur gear reduction box；

Steering drive axle, one end passes through the conic reducer, and is connect with the driven gear of the conic reducer.

2. pilotless automobile electric wire-control transfer according to claim 1, which is characterized in that the steering motor It is arranged vertically with the steering drive axle.

3. pilotless automobile electric wire-control transfer according to claim 2, which is characterized in that the steering motor It is fixedly mounted on the reduction gearbox of bevel gear.

4. pilotless automobile electric wire-control transfer according to claim 3, which is characterized in that the spur gear subtracts The reduction ratio of fast case is 2：1.

5. pilotless automobile electric wire-control transfer according to claim 3 or 4, which is characterized in that the straight-tooth The output axis connection that the driving gear of wheel reduction box passes through flat key and steering motor.

6. pilotless automobile electric wire-control transfer according to claim 5, which is characterized in that the spur gear subtracts The output axis connection that the driven gear of fast case passes through flat key and spur gear reduction box.

7. pilotless automobile electric wire-control transfer according to claim 6, which is characterized in that the spur gear subtracts The input shaft of fast case is connected on the babinet of the spur gear reduction box with output shaft by bearing.

8. a kind of pilotless automobile rotating direction control method uses the electronic line of pilotless automobile as described in claim 1~7 Control transfer, which is characterized in that

Vehicle is planned to the corner of the tangent line of turning path and the angle α of vehicle body central axes, vehicle velocity V and steering drive axle respectively θ is converted to the quantification gradation in fuzzy domain；

The vehicle is planned that the tangent line of turning path inputs fuzzy control model, institute with the angle α of vehicle body central axes with vehicle velocity V The tangent line and the angle α of vehicle body central axes for stating the planning turning path of the vehicle in fuzzy control model are divided into 7 grades, will Vehicle velocity V is divided into 7 grades；

Fuzzy control model output is the rotational angle theta of steering drive axle, and the rotational angle theta of steering drive axle is divided into 7 grades；According to steering The rotational angle theta of transmission shaft controls the steering of vehicle.

9. pilotless automobile rotating direction control method according to claim 8, which is characterized in that the vehicle planning turning The domain of the tangent line in path and the angle α of vehicle body central axes is [- 90,90], and the domain of vehicle velocity V is [0,120], setting quantization because Son is all 1, and the rotational angle theta of steering drive axle is [- 900,900].

10. pilotless automobile rotating direction control method according to claim 9, which is characterized in that according to the friction on road surface Coefficient μ, vehicle weight M, length of wagon L and body width W are corrected the transmission shaft rotational angle theta, the transmission shaft after correction Corner is：

Wherein, e is the truth of a matter of natural logrithm.