An autonomous formula racing car steering system

Abstract

This invention belongs to the field of autonomous driving, specifically relating to a steering system for an autonomous Formula One racing car. The autonomous Formula One racing car steering system includes a steering wheel, a transmission mechanism, a steering mechanism, and a power unit. One end of the transmission mechanism is connected to the steering wheel, and the other end is connected to the steering mechanism. The power unit is connected to the steering mechanism and provides power to the steering mechanism when the car is in autonomous driving mode. The rack has a first tooth and a second tooth, the transmission mechanism has a first gear, and the power unit has a second gear. The first gear meshes with the first tooth, and the second gear meshes with the second tooth. This invention directly connects the power unit to the second tooth, eliminating the need for an additional connecting mechanism between the power unit and the rack, greatly simplifying the structure of the entire steering system. This results in a more compact system with less space occupied, and it does not interfere with the driver's normal driving operations.

Description

Technical Field

[0001] This invention belongs to the field of Formula racing technology, specifically relating to a steering system for an unmanned Formula racing car. Background Technology

[0002] Motorsport originated in 1894, with no restrictions on participating vehicles at the time. It wasn't until the Fédération Internationale de l'Automobile (FIA) was established in 1904 that, for reasons of fairness and safety, attempts were made to classify and restrict participating vehicles. Early classifications explored various angles, including maximum vehicle weight, fuel consumption, and cylinder radius, but the results were unsatisfactory. It wasn't until the concept of cylinder capacity was introduced that satisfactory results were achieved. This is the meaning of "Formula," a set of restrictive standards for all participating cars. Simply put, it involves producing cars according to a formula (not a mathematical equation), hence the name "Formula racing car."

[0003] To promote talent development in our automotive industry, the China University Student Autonomous Driving Formula Competition will be held. In this competition, university students will modify existing race cars to research autonomous driving technology. The competition requires achieving autonomous driving based on the skills a human driver can use. The steering system plays a crucial role in the entire Formula car development process. Compared to passenger cars, racing car chassis operate in more extreme environments, with more curves and higher cornering speeds. This places higher demands on the steering system. Besides basic design requirements such as structural reliability and relatively easy steering, sufficient stability is paramount. Currently, Formula car steering systems are generally C-EPS (Column-EPS), meaning the motor operates on the steering column. This motor is typically suspended behind the steering wheel. Using this system can cause interference between the motor and the driver's knees, affecting the driver's normal operation. Furthermore, the high center of gravity of the motor in existing steering systems raises the overall center of gravity of the car, negatively impacting driver stability. In addition, existing steering systems require an intermediate mechanism to connect the motor suspended behind the steering wheel to the steering column, resulting in a complex structure that occupies a large space. In the confined space of a race car, this can interfere with the driver's operation. Summary of the Invention

[0004] To address the technical challenge of existing racing car steering systems failing to enhance stability while minimizing driver interference during normal driving, this invention provides a steering system for an unmanned Formula One racing car.

[0005] This invention is achieved using the following technical solution: a steering system for an unmanned Formula One race car, comprising: a steering wheel, a transmission mechanism, a steering mechanism, and a power unit. One end of the transmission mechanism is connected to the steering wheel, and the other end of the transmission mechanism is connected to the steering mechanism. The steering wheel is used to provide steering power to the steering mechanism through the transmission mechanism when the unmanned Formula One race car is driven by a human. The power unit is installed on one side of the transmission mechanism and is connected to the steering mechanism. The power unit is used to provide power to the steering mechanism when the unmanned Formula One race car is driven autonomously.

[0006] The steering mechanism includes a rack and at least one rack limiting device. The rack is inserted into the rack limiting device along its axial direction, and the rack limiting device is used to limit the radial movement of the rack. The rack has a first tooth and a second tooth. In the axial direction of the rack, the second tooth is disposed on one side of the first tooth. In the radial direction of the rack, the second tooth is horizontally disposed. The first tooth is inclined downward from below the second tooth and faces the transmission mechanism. The angle between the horizontal planes where the first tooth and the second tooth are located is 110°. The transmission mechanism includes a gear first that meshes with the first tooth. The meshing of the gear first and the first tooth converts the rotation of the steering wheel into the axial movement of the rack. The power unit includes a gear second that meshes with the second tooth. The gear second is horizontally disposed above the second tooth. The meshing of the gear second and the second tooth converts the power of the power unit into the axial movement of the rack.

[0007] As a further improvement of the present invention, the power unit further includes a motor, a worm gear reducer, and a clutch. The input end of the worm gear reducer is connected to the motor, one end of the clutch is connected to the output end of the worm gear reducer, and the other end of the clutch is connected to the second gear. The clutch enables the connection and disengagement between the worm gear reducer and the second gear. When the unmanned Formula car is in unmanned driving mode, the clutch is engaged, and the clutch connects the worm gear reducer and the second gear respectively. When the unmanned Formula car is in manned driving mode, the clutch is disengaged, and the worm gear reducer and the second gear are disconnected.

[0008] The shaft center of the clutch and the shaft center of the output end of the worm gear reducer are both on the central axis of the second gear. The shaft center of the motor is on the straight line where the shaft center of the input end of the worm gear reducer is located. In the axial direction of the second gear, the input end is located below the output end. The straight line where the shaft center of the motor is located is perpendicular to the straight line where the shaft center of the clutch is located. The clutch, the worm gear reducer, and the motor form an L-shaped structure.

[0009] As a further improvement of the present invention, the second gear is located in the length direction of the rack, and the distance of the second gear to the centerline of the length direction is in the range of one-third to two-fifths of the distance from the end of one side of the rack to the centerline.

[0010] As a further improvement of the present invention, the transmission mechanism further includes a quick-release assembly, a drive shaft, and a housing. One end of the quick-release assembly is fixedly connected to the steering wheel. Both ends of the drive shaft are provided with universal joints. One end of the drive shaft is connected to the end of the quick-release assembly away from the steering wheel through the universal joint. The housing is mounted on the rack, the gear is mounted inside the housing, and the other end of the drive shaft is connected to the gear through the universal joint.

[0011] As a further improvement of the present invention, the transmission ratio of the worm gear reducer is greater than or equal to 25.

[0012] As a further improvement of the present invention, the maximum steering angle of the outer wheels of the unmanned Formula One race car is α. max , Where L is the wheelbase between the outer and inner wheels of the autonomous Formula One car, c is the kingpin offset of the autonomous Formula One car, and R... min Let be the minimum turning radius of the driverless Formula One race car.

[0013] As a further improvement of the present invention, the angular transmission ratio i of the steering system of the unmanned Formula One racing car w The ratio is 5:1; the maximum steering angle of the steering wheel is β. max ,β max =α max* i w ;

[0014] The stroke of the rack is L1. Where, β max The maximum turning angle of the steering wheel is given by m, where m is the module of gear one and z is the number of teeth of gear one.

[0015] As a further improvement of the present invention, the quick-release assembly includes a quick-release device, a quick-release shaft, and a quick-release shaft fixing device. One end of the quick-release device is connected to the steering wheel, and the other end of the quick-release device is connected to the quick-release shaft. The quick-release shaft fixing device is installed on the quick-release shaft and is used to limit and fix the quick-release shaft. The other end of the quick-release shaft is connected to the drive shaft through the universal joint.

[0016] As a further improvement of the present invention, the clutch is an electromagnetic clutch.

[0017] As a further improvement of the present invention, gear one and gear two are two identical spur gears.

[0018] As a further improvement of the present invention, the first gear has 17 teeth, the first gear has a module of 1.5, the first gear has a pressure angle of 20°, and the first gear has a helix angle of 0°.

[0019] The technical solution provided by this invention has the following beneficial effects:

[0020] (1) By directly connecting the power unit to the rack, the present invention eliminates the need for an additional connecting mechanism to connect the power unit and the rack, greatly simplifying the structure of the entire steering system, making the entire steering system more compact, occupying less space, and not interfering with the driver's normal driving operation.

[0021] (2) This invention sets gear two horizontally. This horizontal orientation allows gear two, the clutch, the worm gear reducer, and the motor connected to it to be horizontally positioned at the bottom of the race car, within the space below the driver's legs. This improves space utilization and makes the entire steering system design more rational. Furthermore, by setting the angle between gear one and gear two in the horizontal plane to 110°, this invention reduces the universal joint angle from approximately 35° to approximately 25°, thereby reducing the universal joint speed unevenness coefficient from 0.4016 to 0.1969, enhancing the stability of the race car. Therefore, the steering system of this invention can maintain the stability of the race car while simultaneously placing the power unit at the bottom of the car, within the space below the driver's legs, thus reducing the interference caused by the power unit to the driver during driving.

[0022] (3) This invention designs a worm gear reducer, which utilizes its high transmission ratio and small size to increase the space in the front compartment of the race car. It perfectly utilizes the change of its transmission direction to place the motor in the middle of the bottom of the front compartment, and uses the center distance to lower the position of the motor, which is convenient for fixing and lowers its center, so that the power unit is located in the space below the driver's legs, thereby improving its space utilization. Attached Figure Description

[0023] Figure 1 A perspective view of a steering system for an unmanned Formula One racing car provided by the present invention.

[0024] Figure 2 This is a schematic diagram showing the various components of the power unit in this invention when they are separated.

[0025] Figure 3 This is an enlarged structural schematic diagram of the steering mechanism in this invention.

[0026] Figure 4 This is a schematic diagram of the included angle between tooth one and tooth two in this invention.

[0027] Figure 5 This is an enlarged schematic diagram of a portion of the steering system of the unmanned Formula One racing car in this invention.

[0028] Figure 6 This is a front view of the steering system for the unmanned Formula One race car in this invention.

[0029] Figure 7 This is a top view of the steering system of the unmanned Formula One race car in this invention.

[0030] The following are labeled in the diagram: 1. Steering wheel; 21. Quick release mechanism; 22. Quick release shaft fixing device; 23. Quick release shaft; 24. Universal joint; 25. Gear 1; 26. Drive shaft; 27. Housing 1; 31. Rack; 311. Gear 1; 312. Gear 2; 313. Rack joint; 32. Rack limit device; 41. Gear 2; 42. Motor; 43. Worm gear reducer; 431. Input end; 432. Output end; 44. Clutch. Detailed Implementation

[0031] The present invention will now be further described in conjunction with specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments.

[0032] In the description of this invention, it should be noted that directional terms such as "center," "lateral," "longitudinal," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation and positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These are used only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. They should not be construed as limiting the specific scope of protection of this invention. The terms "first," "second," etc., in the specification and claims of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. The terms "comprising" and "having," and any variations thereof, in the specification and claims of this invention, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or devices.

[0033] A steering system for an autonomous Formula One car, such as Figure 1 As shown, it includes a steering wheel 1, a transmission mechanism, a steering mechanism, and a power unit. One end of the transmission mechanism is connected to the steering wheel 1, and the other end is connected to the steering mechanism, allowing the steering wheel 1 to provide steering power to the steering mechanism via the transmission mechanism. The power unit is mounted on one side of the transmission mechanism and is connected to the steering mechanism; the power unit provides power to the steering mechanism when the vehicle is not in use.

[0034] Please refer to Figure 1 and Figure 2 The transmission mechanism includes a quick-release assembly, a drive shaft 26, a gear 25, and a housing 27. One end of the quick-release assembly is fixedly connected to the steering wheel 1. Both ends of the drive shaft 26 are equipped with universal joints 24. One end of the drive shaft 26 is connected to the end of the quick-release assembly away from the steering wheel 1 via the universal joint 24, and the other end of the drive shaft 26 is connected to the gear 25 via the universal joint 24. The steering wheel 1 and the transmission mechanism allow the driver to rotate the steering wheel 1 when someone is driving. The steering wheel 1 transmits power to the steering mechanism sequentially through the quick-release assembly, the drive shaft 26, and the gear 25, enabling the steering mechanism to achieve steering. It is understood that the quick-release assembly allows for the rapid removal of the steering wheel 1 from the drive shaft 26, facilitating later maintenance or replacement.

[0035] It is understandable that the universal joint 24 can be a cross-type universal joint 24. The cross-type universal joint 24 has a large angle compensation capability, a compact and reasonable structure, high transmission efficiency, and increases its flexibility in installation and use.

[0036] Further, please refer to Figure 2 and Figure 3 The steering mechanism includes a rack 31 and at least one rack limiting device 32. The rack 31 is inserted into the rack limiting device 32 along its axial direction, and the rack limiting device 32 is used to limit the radial movement of the rack 31. The rack 31 is provided with a first tooth 311 and a second tooth 312. The second tooth 312 is located on one side of the first tooth 311 in the axial direction of the rack 31, and the second tooth 312 is on the same side as the power unit. This allows the power unit to be directly connected to the second tooth 312, eliminating the need for an additional connecting mechanism between the power unit and the rack 31. This greatly simplifies the structure of the entire steering system, making it more compact, space-saving, and less likely to interfere with the driver's normal driving operations. In the radial direction of rack 31, gear 2 312 is arranged horizontally. This horizontal arrangement allows gear 2 41, clutch 44, worm gear reducer 43, and motor 42, all connected to it, to be horizontally positioned at the bottom of the race car, placing them within the space below the driver's legs. This improves space utilization and makes the entire steering system design more rational. Gear 1 311 is inclined downwards and to the left from below gear 2 312, facing gear 1 25. (Please refer to...) Figure 3 and Figure 4 ,in Figure 4 The X-axis can be the horizontal plane where gear 312 is located, and the Y-axis is the straight line where gear 311 is located. The angle between the straight line where gear 311 is located and the horizontal plane where gear 312 is located is 110°, that is, the angle between the straight line where gear 311 is located and the vertical plane is 20°. By setting gear 311 to an inclination angle of 20° with the vertical plane, the included angle of universal joint 24 can be reduced from about 35° to about 25°. This reduces torque fluctuations when steering through steering wheel 1 and transmission mechanism, enhances the stability of drive shaft 2626 when the race car is turning, reduces the wobble of gear 25, thereby reducing the impact on gear 25 during steering and extending the service life of gear 25. Here, the included angle of universal joint 24 is the angle between the central axis of universal joint 24 and the central axis of drive shaft 26.

[0037] The rotational non-uniformity coefficient of the universal joint 24 is k, where k = sinθtanθ, and θ is the included angle of the universal joint 24.

[0038] In this embodiment, there are two universal joints 24, which are named Universal Joint One and Universal Joint Two. One end of Universal Joint One is connected to the steering wheel 1, and the other end is connected to one end of the drive shaft 26. One end of Universal Joint Two is connected to the other end of the drive shaft 26, and the other end is connected to the gear. The included angle of Universal Joint One is the angle between the central axis of Universal Joint One and the central axis of the drive shaft 26. The included angle of Universal Joint Two is the angle between the central axis of Universal Joint Two and the central axis of the drive shaft 26. In the actual design process, in order to make the output shaft speed of Universal Joint Two equal to the input shaft speed of Universal Joint One while changing the transmission direction, the included angles of Universal Joint One and Universal Joint Two are set to be the same. Therefore, in this embodiment, the rotational unevenness coefficient of Universal Joint One and Universal Joint Two are the same.

[0039] The included angle of the universal joint 24 in the existing steering system is generally 35°, and the coefficient of rotational unevenness of the universal joint 24 in the existing steering system is k1.

[0040] k1=sin35°tan35°≈0.5736×0.7=0.4016;

[0041] In this embodiment, the included angle of the universal joint 24 in the steering system is 25°, and the rotation non-uniformity coefficient of the universal joint 24 in the steering system in this embodiment is k2.

[0042] k2=sin25°tan25°≈0.4226×0.466=0.1969;

[0043] As shown in the above data, this embodiment reduces the included angle of universal joint 24 from approximately 35° to approximately 25° by adjusting the tilt angle of gear 311. This reduces the rotational speed unevenness coefficient of universal joint 24 from 0.4016 to 0.1969, a reduction of approximately 50%. By reducing the rotational speed unevenness coefficient of universal joint 24, a shorter universal joint 24 connecting gear 25 can be used compared to existing technologies, thereby reducing the lateral torque of gear 25 during steering, thus reducing gear wobbling and extending gear life. Furthermore, the steering system assembled according to this embodiment was tested on a race car. The results showed that the free travel of the race car using the steering system of this invention decreased from 6.2 degrees to 3.5 degrees. Reduced free travel accelerates the response speed of the steering system and increases its steering speed.

[0044] In the actual design process, a groove can be designed on gear 25, which can be directly connected to universal joint 24, so that there will be no relative rotation between universal joint 24 and gear 25, thereby improving the stability when universal joint 24 drives gear 25 to rotate.

[0045] In this embodiment, there are two rack limiting devices 32, which are symmetrically distributed along the axial direction of the rack 31. Each rack limiting device 32 includes a mounting base and a sliding bearing. The sliding bearing is sleeved on the outside of the rack 31, and the sliding bearing and the mounting base can be interference-fitted. The interference fit can restrict the four degrees of freedom of the rack 31 other than axial displacement and rotation. The mounting base is also provided with mounting holes, through which the mounting base can be fixed to the race car.

[0046] Please refer to Figure 3 The rack 31 is also provided with rack 31 connectors at both ends. The rack 31 connectors are located at the ends of the rack 31 and are used to connect with other components.

[0047] Please refer to Figures 2 to 5 The power unit includes a second gear 41, a motor 42, a worm gear reducer 43, and a clutch 44. The second gear 41 is horizontally positioned above the rack 31 and meshes with the second gear 312. One end of the clutch 44 is connected to the second gear 41, and the other end is connected to the output end 432 of the worm gear reducer 43. The motor 42 is connected to the input end 431 of the worm gear reducer 43. The motor 42 transmits power to the second gear 41 through the worm gear reducer 43 and the clutch 44. The second gear 41, by meshing with the second gear 312, drives the rack 31 to move in its axial direction. In this embodiment, the clutch 44 is used to connect and disconnect the worm gear reducer 43 and the second gear 41. When the autonomous racing car is in autonomous driving mode, the clutch 44 is engaged, connecting both the worm gear reducer 43 and the second gear 41. At this time, the motor 42 is started. The motor 42 can provide torque, which is then amplified by the worm gear reducer 43. The torque is then transmitted to gear 41 through the clutch 44. Gear 41 meshes with gear 312 to drive the rack 31 to move, so as to realize the steering of the unmanned Formula car in unmanned driving mode.

[0048] In this embodiment, the rotation of the rack 31 itself is limited by the meshing of gear 41 and gear 312 and gear 25 and gear 311.

[0049] In this embodiment, the worm gear reducer 43 and the clutch 44 can be connected by a key drive. The advantage of using a key drive is that it facilitates disassembly and reassembly of the worm gear reducer 43 and the clutch 44. Compared to spline and bolt connections, a standard flat key connection can be directly fitted, eliminating the need for special tools during installation. Furthermore, in this embodiment, a simulation analysis of the structural strength between the key-connected worm gear reducer 43 and the clutch 44 is conducted. The analysis concludes that the stress at the key connection is not significant, and the connection strength meets the requirements. Therefore, a key drive connection can be used between the worm gear reducer 43 and the clutch 44.

[0050] During installation, please refer to Figure 7 Gear 2 41 is located along the length of rack 31, and the distance between gear 2 41 and the centerline along the length of rack 31 is between one-third and two-fifths of the distance from the end of one side of rack 31 to the centerline, so that the entire rack 31 can operate normally.

[0051] In this embodiment, the distance between the centerline of gear 2 41 and rack 31 in the length direction can be 65mm to 70mm.

[0052] It is understood that in this embodiment, the clutch 44 can be an electromagnetic clutch 44. The connection between the clutch 44 and the gear 41 and the worm gear reducer 43 is achieved by energizing the electromagnetic clutch 44, and the disconnection between the clutch 44 and the gear 41 and the worm gear reducer 43 is achieved by de-energizing the electromagnetic clutch 44.

[0053] Gear 1 25 and Gear 2 41 can be two identical spur gears.

[0054] The number of teeth of gear 25 can be 17, the module of gear 25 can be 1.5, the pressure angle of gear 25 can be 20°, and the helix angle of gear 25 can be 0°.

[0055] When the autonomous Formula car is in manned mode, the electromagnetic clutch 44 is de-energized, and gear 41 and the electromagnetic clutch 44 are disconnected. The steering wheel 1 is manually turned to apply torque, which drives gear 25 to rotate via the drive shaft 26 and universal joint 24. With gear 25 meshing with gear 311, rack 31 moves axially, pulling the tie rod on the car. This, in turn, causes the wheels to rotate around the main shaft via the steering knuckle arm, thus enabling the autonomous Formula car to steer in manned mode. It is understood that how rack 31 drives the wheels to rotate around the main shaft via the tie rod and steering knuckle arm is existing technology and will not be described in detail in this embodiment.

[0056] In this embodiment, the axis of the clutch 44 and the axis of the output end 432 of the worm gear reducer 43 are both on the central axis of the second gear 41. The axis of the motor 42 is on the same straight line as the axis of the input end 431 of the worm gear reducer 43. In the axial direction of the second gear 41, the input end 431 is located below the output end 432. In this embodiment, the input end 431 is located approximately 30mm below the output end 432. This allows for direct connection of the power unit to the rack 31, while the location of the input end 431 of the worm gear reducer 43 below the output end 432 effectively lowers the center of gravity of the motor 42, and also better secures the motor 42 to the race car.

[0057] In this embodiment, a worm gear reducer 43 is selected because it has a high transmission ratio. If other reducers, such as bevel gear reducers, are used, their transmission ratios are smaller. In actual assembly, multiple stages of bevel gears would be needed to increase the transmission ratio, which would complicate the entire steering system structure and occupy more space. Therefore, under the same transmission ratio conditions, the worm gear reducer 43 is smaller in size than other reducers and is more suitable for use in racing cars.

[0058] This invention designs a worm gear reducer, which utilizes its high transmission ratio and small size to increase the space in the front compartment of the race car. It perfectly utilizes the change in its transmission direction to place the motor 42 in the middle of the bottom of the front compartment, and uses the center distance to lower the position of the motor 42, which is convenient for fixing and lowers its center, so that the power unit is located in the space below the driver's legs, improving its space utilization.

[0059] In this embodiment, the transmission ratio of the worm gear reducer 43 is greater than or equal to 25.

[0060] In this embodiment, please refer to Figure 5 and Figure 6 The axis of motor 42 is perpendicular to the axis of clutch 44, allowing clutch 44, worm gear reducer 43, and motor 42 to form an L-shaped structure. In actual operation, the lowered center of gravity of motor 42 facilitates its fixation, while the L-shaped structure of the entire power unit effectively utilizes the space under the driver's legs, improving space utilization. This also ensures the power unit is compact enough without interfering with the driver's normal operation, resulting in a more ingenious and rational steering system design.

[0061] Understandably, in existing technologies, the steering wheel torque (M) in the steering system of an autonomous Formula One racing car is 1 hand-held. hThe torque is approximately 20.35 N·m; the detailed calculation process can be found in later paragraphs. While the transmission efficiency of the worm gear reducer 43 is not high, its minimum output torque is still 22.2 N·m, which is greater than the steering wheel torque (M) in a Formula One car steering system. h This is because it can be proven that the worm gear reducer 43 in this embodiment meets the steering requirements.

[0062] The housing 27 is mounted on the rack 31. During actual installation, the housing 27 can be fixed to the race car with bolts. The gear 25 is installed inside the housing 27 and can rotate within it. The universal joint 24 on the drive shaft 26, near the gear 25, extends into the housing 27 and connects to the gear 25. In actual operation, if the unmanned Formula race car is being driven, the power unit and rack 31 are disconnected. The driver can apply torque by turning the steering wheel 1, which, in turn, drives the rack 31 axially through the quick-release assembly, drive shaft 26, and the meshing of gears 25 and 311. The rack 31 then drives the tie rod on the unmanned Formula race car, which in turn rotates the wheels around the main shaft via the steering knuckle arm, thus achieving steering.

[0063] Please refer to Figure 6 The quick-release assembly includes a quick-release device 21, a quick-release shaft 23, and a quick-release shaft 23 fixing device 22. One end of the quick-release device 21 is connected to the steering wheel 1, and the other end is connected to one end of the quick-release shaft 23. The other end of the quick-release shaft 23 is connected to the drive shaft 26 via a universal joint 24. The quick-release shaft 23 fixing device 22 is sleeved on the outside of the quick-release shaft 23 and is used to limit the quick-release shaft 23, so that the quick-release shaft 23 can only rotate along its axial direction and cannot move along its axial direction. Thus, the steering wheel 1 can control the drive shaft 26 to rotate through the quick-release assembly. The drive shaft 26 drives the gear 25 to rotate. Through the meshing of the gear 25 and the tooth 311, the rotation of the steering wheel 1 is converted into the axial movement of the rack 31. The rack 31 then acts on the tie rod of the autonomous racing car, and finally, through the steering knuckle arm, the wheels of the racing car rotate around the main shaft, thereby achieving the purpose of steering.

[0064] In actual competition, the competition rules require the minimum turning radius of the track to be 9m. However, considering the possibility that the car may leave the track and return to it, as well as the actual track conditions and feedback data from the car's steering system during previous competitions, and taking into account the possibility of understeer, the minimum turning radius of the car is designed to be 3.5m in this embodiment.

[0065] It is understood that, in this embodiment, the angular transmission ratio i of the steering system of the unmanned Formula One racing car is... w It could be 5:1.

[0066] It is understood that, in this embodiment, the maximum steering angle of the outer wheels of the autonomous Formula One race car is α. max ;

[0067] Where L is the wheelbase between the outer and inner wheels of the autonomous Formula car, which is 1580mm; c is the kingpin offset of the autonomous Formula car, which is 30mm; R min The minimum turning radius for an autonomous Formula One car is 3500mm.

[0068] Right now

[0069] Therefore, α max =27°, meaning the maximum turning angle of the outer wheel is 27°. This is based on the angular transmission ratio i of the steering system in an autonomous Formula One car. w Given a ratio of 5:1, define β max This is the maximum turning angle of steering wheel 1, i.e. β can be obtained max The angle is 135°. At this angle, the self-driving Formula car can be easily steered using steering wheel 1 without the problem of crossing hands, thus improving the convenience and smoothness of steering using steering wheel 1 in manned mode.

[0070] Define the stroke of rack 31 as L1. Define m as the module of gear 25, which can be 1.5. Define z as the number of teeth of gear 25, which can be 17. The pressure angle of gear 25 can be 20°, and the helix angle of gear 25 can be 0°.

[0071] According to the formula Where, β max is the maximum turning angle of steering wheel 1, m is the module of gear 25, and z is the number of teeth of gear 25.

[0072] Right now

[0073] The travel of rack 31 can be 60mm.

[0074] In this scheme, the steering wheel torque M is also specified. h The magnitude of the torque is determined as follows: Generally, the vehicle's turning resistance torque is the largest when stationary, and it decreases as the vehicle speed increases. In this embodiment, the turning resistance torque M of the autonomous Formula One race car can be calculated first. R Then, by turning in place, the resistance torque MR To calculate the steering wheel torque (M) of a Formula One self-driving car. h .

[0075] In this embodiment, the steering wheel torque of the unmanned Formula One race car is calculated using the following formula:

[0076]

[0077] Among them, M R L is the turning resistance torque of a Formula One car while stationary, measured in N·m. d1 L is the length of the steering rocker arm, expressed in mm. d2 L is the length of the steering knuckle arm, expressed in mm. d1 / L d2 The value of is generally between 0.85 and 1.1, and in this embodiment it can be approximated as 1. w η is the angular gear ratio of the steering system, with a value of 5:1. SG The steering efficiency of the steering system is 90%.

[0078] The stationary turning resistance torque M of the unmanned Formula One car R The calculation is as follows:

[0079] Where f is the coefficient of sliding friction between the wheel and the ground, which is usually 0.7; G1 is the vertical load on the steering wheel, which is in N; and p is the tire inflation pressure, which is usually 0.08 MPa.

[0080] Where G1 = M 车 ×K a ×g, M 车 The total vehicle weight is 330 kg; K a is the load distribution factor, which means that 43% of the vehicle's mass is distributed to the front wheels, and its value is 0.43; g is the gravitational acceleration, and its value is 9.8.

[0081] The calculation yields G1 = M 车 ×K a ×g=330*0.43*9.8=1455.3N;

[0082] Therefore, we obtain

[0083] The in-situ turning resistance torque M of the driverless Formula One car R M was calculated h ;

[0084]

[0085] Furthermore, in this embodiment, the torque M of the steering wheel of the unmanned Formula One racing car can also be controlled via hand torque M. h To calculate the steering wheel force F. h , Among them, D sw The diameter of the steering wheel is 240mm.

[0086] Right now

[0087] In this embodiment, the minimum output torque of the selected worm gear reducer 43 is 22.2 N·m, while the calculated steering wheel torque M... h The torque is 20.35 N·m. The output torque of the worm gear reducer 43 is greater than the steering wheel torque of the unmanned racing car, thus proving that the worm gear reducer 43 selected in this embodiment can meet the steering requirements.

[0088] Calculate the steering wheel force F. h Its value is 84.79N, while a review of the literature shows that the maximum steering force F required in the national standard GB176754.1.1 is... a For less than or equal to 150N, F h The value is less than F a If so, it means that the steering system in this embodiment meets the actual requirements.

[0089] In this design, the selected motor 42 has a rated power of 220W and a rated output torque of 1.27±10% N·m. The minimum required transmission ratio for this motor 42 is set to i.

[0090] Among them, M h M1 is the steering wheel torque of 1 hand, which is 20.35 N·m; M2 is the rated output torque of motor 42, which is 1.27 N·m; η is the transmission efficiency of motor 42, which is 70%.

[0091] Right now

[0092] Therefore, we selected a worm gear reducer 43 with a transmission ratio greater than or equal to 25, which is greater than the minimum transmission ratio required by the motor 42 and meets the design requirements.

[0093] It is understandable that the total output torque M of the worm gear reducer 43 with a transmission ratio of 25 is M = M1 × η × i a Where M1 is the rated output torque of motor 42, which is 1.27 N·m; η is the transmission efficiency of motor 42, which is 70%; i aThe transmission ratio of the worm gear reducer 43 is 25.

[0094] That is, M = 1.27 × 70% × 25 = 22.23 N·m, while the steering wheel torque for one hand is M h The value is 20.35 N·m. That is, the total output torque M of the worm gear reducer 43 is greater than the steering wheel torque M1. h Therefore, it can be proven that the steering system designed in this embodiment is feasible.

[0095] The basic principles, main features, and advantages of this invention have been described above. Those skilled in the art should understand that this invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely principles of the invention. Various changes and modifications can be made without departing from the spirit and scope of the invention, and all such changes and modifications fall within the scope of the invention as claimed. The scope of protection claimed by this invention is defined by the appended claims and their equivalents.

Claims

1. A steering system for an unmanned Formula One racing car, characterized in that, It includes: a steering wheel (1), a transmission mechanism, a steering mechanism, and a power unit. One end of the transmission mechanism is connected to the steering wheel (1), and the other end of the transmission mechanism is connected to the steering mechanism. The steering wheel (1) is used to provide steering power to the steering mechanism through the transmission mechanism when the unmanned Formula car is driven by a human. The power unit is installed on one side of the transmission mechanism and is connected to the steering mechanism. The power unit is used to provide power to the steering mechanism when the unmanned Formula car is driven by an unmanned person. The steering mechanism includes a rack (31) and at least one rack limiting device (32). The rack (31) is inserted into the rack limiting device (32) along its axial direction. The rack limiting device (32) is used to limit the radial movement of the rack (31). The rack (31) is provided with a first tooth (311) and a second tooth (312). In the axial direction of the rack (31), the second tooth (312) is disposed on one side of the first tooth (311). In the radial direction of the rack (31), the second tooth (312) is horizontally disposed. The first tooth (311) is inclined downward from below the second tooth (312) and the first tooth (311) faces the first tooth. The transmission mechanism includes a gear 1 (311) meshing with the horizontal plane containing the first gear (311) and the second gear (312) with an angle of 110°. The transmission mechanism includes a gear 1 (25) meshing with the first gear (311), and the rotation of the steering wheel (1) is converted into the axial movement of the rack (31) through the meshing of the gear 1 (25) and the first gear (311). The power device includes a gear 2 (41) meshing with the second gear (312), and the gear 2 (41) is horizontally positioned above the second gear (312). The power of the power device is converted into the axial movement of the rack (31) through the meshing of the gear 2 (41) and the second gear (312). The power unit also includes a motor (42), a worm gear reducer (43), and a clutch (44). The input end (431) of the worm gear reducer (43) is connected to the motor (42). One end of the clutch (44) is connected to the output end (432) of the worm gear reducer (43), and the other end of the clutch (44) is connected to the gear two (41). The clutch (44) enables the connection and separation between the worm gear reducer (43) and the gear two (41). When the unmanned Formula car is in unmanned driving mode, the clutch (44) is engaged, and the clutch (44) is connected to the worm gear reducer (43) and the gear two (41) respectively. When the unmanned Formula car is in manned driving mode, the clutch (44) is disengaged, and the worm gear reducer (43) and the gear two (41) are disconnected. The axis of the clutch (44) and the axis of the output end (432) of the worm gear reducer (43) are both on the central axis of the second gear (41). The axis of the motor (42) is on the straight line where the axis of the input end (431) of the worm gear reducer (43) is located. In the axial direction of the second gear (41), the input end (431) is located below the output end (432). The straight line where the axis of the motor (42) is located is perpendicular to the straight line where the axis of the clutch (44) is located. The clutch (44), the worm gear reducer (43) and the motor (42) can form an L-shaped structure.

2. The unmanned Formula One car steering system as described in claim 1, characterized in that, The second gear (41) is located along the length of the rack (31), and the distance from the second gear (41) to the centerline of the length direction is between one-third and two-fifths of the distance from the end of one side of the rack (31) to the centerline.

3. The unmanned Formula One car steering system as described in claim 1, characterized in that, The transmission mechanism also includes a quick-release assembly, a drive shaft (26), and a housing (27). One end of the quick-release assembly is fixedly connected to the steering wheel (1). Both ends of the drive shaft (26) are provided with universal joints (24). One end of the drive shaft (26) is connected to the end of the quick-release assembly away from the steering wheel (1) through the universal joint (24). The housing (27) is mounted on the rack (31). The gear (25) is mounted inside the housing (27). The other end of the drive shaft (26) is connected to the gear (25) through the universal joint (24).

4. The unmanned Formula One car steering system as described in claim 1, characterized in that, The transmission ratio of the worm gear reducer (43) is greater than or equal to 25.

5. The unmanned Formula One car steering system as described in claim 1, characterized in that, The maximum steering angle of the outer wheels of the unmanned Formula One race car is α. max , Where L is the wheelbase between the outer and inner wheels of the autonomous Formula car, c is the kingpin offset of the autonomous Formula car, and R... min Let be the minimum turning radius of the driverless Formula One race car.

6. The unmanned Formula One car steering system as described in claim 3, characterized in that, The angular transmission ratio i of the steering system of the unmanned Formula One racing car w The ratio is 5:1; the maximum turning angle of the steering wheel (1) is β. max ,β max =α max ×i w ; The stroke of the rack (31) is L1. , where β max The maximum turning angle of the steering wheel (1) is m, the module of the gear (25) is m, and the number of teeth of the gear (25) is z.

7. The unmanned Formula One car steering system as described in claim 3, characterized in that, The quick-release assembly includes a quick-release device (21), a quick-release shaft (23), and a quick-release shaft (23) fixing device (22). One end of the quick-release device (21) is connected to the steering wheel (1), and the other end of the quick-release device (21) is connected to the quick-release shaft (23). The quick-release shaft (23) fixing device (22) is installed on the quick-release shaft (23) to limit and fix the quick-release shaft (23). The other end of the quick-release shaft (23) is connected to the drive shaft (26) through the universal joint (24).

8. The unmanned Formula One car steering system as described in claim 3, characterized in that, The universal joint (24) is a cross-type universal joint (24).

9. The unmanned Formula One car steering system as described in claim 1, characterized in that, The clutch (44) is an electromagnetic clutch (44).

10. The unmanned Formula One car steering system as described in claim 1, characterized in that, The first gear (25) and the second gear (41) are two identical spur gears; the first gear (25) has 17 teeth, the first gear (25) has a module of 1.5, the first gear (25) has a pressure angle of 20°, and the first gear (25) has a helix angle of 0°.

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