GB2533561A

GB2533561A - Improvements in or relating to steering systems for vehicles

Info

Publication number: GB2533561A
Application number: GB1422622.9A
Authority: GB
Inventors: Tonks David
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-12-18
Filing date: 2014-12-18
Publication date: 2016-06-29

Abstract

A vehicle 10, for example a golf buggy, has a steering system 24 which includes a control means 26, for example a joystick, operable to receive a user instruction 28 indicating a desired direction of travel. Control means 26 provides control outputs 30 for drive arrangements 32, typically electric motors which may be provided at each wheel 16, operable to drive the ground wheels 16. Control outputs 30 include drive information for wheels 16, causing vehicle 10 to be turned by the relative speeds of wheels 16 to either side 34, 36 of vehicle 10. The relative speeds may be varied to vary the rate of turn, and outputs 30 may include speed and/or braking information and may provide regenerative braking. Optionally, wheels 16 on opposite sides may be drivable in opposite directions to cause the vehicle to spin.

Description

Improvements in or relating to steering systems for vehicles The present invention relates to steering systems for vehicles.

Steering requirements for vehicles vary according to the size and purpose of the vehicle, driver capability, the nature of the ground on which the vehicle is intended to be used, and other factors. In one scenario, a golf buggy may be used by a golfer and if the golf buggy is to be used on the grass surface of the golf course, the golf buggy must function in a manner which does not cause unacceptable damage to the grass surface. In addition, it is desirable for the golf buggy to be highly manoeuvrable and yet simple to control.

Examples of the present invention provide a steering system for a vehicle having fore and aft directions and ground wheels to either side of the vehicle, the system comprising: a control means operable to receive a user instruction indicating a desired direction of travel; the control means being operable to provide control outputs for drive 20 arrangements operable to drive the ground wheels; and the control outputs being derived by the control means from the user instruction and including respective drive information for the corresponding wheel or wheels, to cause the vehicle to be turned by the relative speeds of the wheels to either side of the vehicle.

The control means may be operable to vary the relative speeds, to set the amount of turn. The control means may provide a first control output for driven wheels to a first side of the vehicle, and a second control output for driven wheels to a second side of the vehicle. Alternatively, the control means may be operable to provide different control outputs for multiple driven wheels to either side of the vehicle.

The control means may be operable to provide control outputs which include speed information. The control means may be operable to provide control outputs which include braking information for causing braking of the corresponding wheel or wheels. The degree of braking instructed by a control output may be independent of the speed of other wheels.

The system may further comprise drive arrangements which include electric motors operable to drive respective wheels. The system may provide an electric motor for each wheel. The control means may be operable to provide control outputs which cause regenerative braking of an electric motor or motors.

The control means may be operable to provide sufficient control outputs to cause all 10 wheels to be driven.

The control means may be operable to receive from a user a spin instruction indicating a desire to spin the vehicle around. The control means may be operable to distinguish between two spin instructions indicating respective desired spin directions. The control means may be operable in response to a spin instruction to derive control outputs to cause wheels on respective sides of the vehicle to be driven in opposite directions.

The control means may be operable to receive a user instruction which indicates a desired speed of travel, and to derive control outputs causing wheels to be driven at a corresponding speed.

The system may further comprise a joystick operable by a user to create a user instruction. The control means may be operable to interpret a direction of deflection of the joystick as indicating a desired direction of travel. The control means may be operable to interpret a degree of deflection of the joystick as indicating a desired speed of travel.

Examples of the present invention also provide a vehicle comprising a steering 30 system as defined above.

All of the ground wheels of the vehicle may be driven in response to control outputs.

The vehicle may include drive arrangements which include a separate drive unit for each wheel. Each drive unit may include an electric motor.

Examples of the present invention will now be described in more detail, by way of example only, and with reference to the accompanying drawings, in which: Fig 1 is a schematic side view of a vehicle which incorporates a steering system according to one example of the invention; Fig 2 is a diagrammatic plan view of elements of the steering system; Fig 3a and b indicate alternative arrangements for part of the steering system of Fig 2; and Fig 4 is a flow diagram indicating an example mode of operation within the steering system of Fig 2.

Vehicle Fig 1 illustrates vehicle 10 having fore and aft directions, indicated respectively by arrows 12, 14. The fore and aft directions 12, 14 define a centre line for the vehicle 10. There are ground wheels 16 to either side of the vehicle 10.

In this example, the vehicle has a seat 18, footrests 20 and handlebars 22, allowing a user to be seated comfortably on the vehicle 10 while driving. In this or other examples, the user may alternatively stand on the vehicle 10 while driving. The vehicle 10 may be designed so that when not in use, it can be folded or collapsed to a compact condition for easy storage. The vehicle 10 may provide a location for carrying items such as a set of golf clubs.

The vehicle 10 is provided with a steering system which will now be described.

Steerinci system The vehicle 10 has a steering system 24 which is most easily described with reference to the remaining figures. However, the location of some items of the steering system 14 is indicated in Fig 1 as one example of many possible options.

The steering system 24 (Fig 2) includes a control means 26 operable to receive at 28 a user instruction indicating a desired direction of travel. The control means 26 is operable to provide control outputs 30 for drive arrangements 32 operable to drive the ground wheels 16. The control outputs 30 are derived by the control means 26 from the user instruction 28 and include respective drive information for the corresponding wheel or wheels 16. As will be described, this will cause the vehicle 10 to be turned by the relative speeds of the wheels 16 to either side 34, 36 of the vehicle 10.

User input device The user instructions at 28 are derived from a user input device indicated generally at 38. The user input device 38 is mounted at a convenient location on the vehicle 10, such as on the handlebars 22. The user input device 38 includes a joystick 40.

The joystick 40 has a central position at 42. A user can push the joystick 40 away from the central position 42. The direction in which the joystick 40 is pushed by the user indicates the direction of travel which is desired by the user. In one example, the degree of deflection of the joystick 40 away from the central position 42 may be used to indicate the speed of travel which is desired by the user.

The user input device 38 provides information about the current position of the joystick 40 by incorporating this in the user instruction 28 supplied to the control means 26. Consequently, the control means 26 is provided with information about the direction of travel which is desired by the user, and may also be provided with information about the speed of travel which is desired by the user.

The user input device 38 also includes two spin controls 44, 46. These may be simple buttons, switches or other convenient control devices. The purpose of the spin controls 44, 46 will be described below. In the event that either of the spin controls 44, 46 is activated, the user input device 38 will incorporate appropriate information in the user instruction 28 to the control means 26, allowing the control means 26 to identify which spin control 44, 46 is being or has been activated.

The joystick 40 and spin controls 44, 46, or alternative devices may be mechanical devices or may alternatively be provided in a "soft" manner, such as by means of a touch-sensitive screen. For example, a touch-sensitive screen may display an image representative of a joystick and spin controls, allowing these controls to be used by a user in a virtual manner.

Drive arrangements Each of the wheels 16 illustrated in Fig 2 has an associated drive arrangement 32 which, in this example, is an electric motor. Power for the electric motors 32 is provided from a battery 48. The control outputs 30 from the control means 26 are conveyed to the electric motors 32, allowing the control means 26 to control the operation of the motors 32. In particular, the control means 26 is able to control the speed of the motors 32. In the example being described, the control means 26 is also able to control the direction of the motors 32 and is able to instruct motors 32 to enter a braking mode, such as a regenerative braking mode in which energy recovered from the braking process is fed back to the battery 48.

In this example, each electric motor 32 is provided with a separate user instruction 28 from the control means 26. However, the user instructions 28 may be the same to each of the electric motors 32 on one side 34 of the vehicle 10, or on the other side 36 of the vehicle 10. In this way, all of the wheels 16 to one side of the vehicle 10 will be driven at the same speed (and in the same direction or in regenerative braking mode, if the control means 26 is able to instruct in this respect).

Control means Fig 3a and b illustrate two alternative arrangements for the control means 26, in more detail. In Fig 3a, a single processor 50 receives the user instruction 28 and processes the information in the instruction 28 to interpret the desired direction of travel and to interpret the desired speed of travel, if that information is contained within the user instruction 28. This information is processed by the control means 26 to derive drive information for the wheels 16 and in particular, to derive speed information. The speed information is incorporated into the control outputs 30 to the motors 32, causing the motors to run at the appropriate speed. The control outputs 30 may also include direction information and information about regenerative braking, causing the motors 32 to run in the corresponding direction, or in regenerative braking mode.

The arrangement of the control outputs 30 allows the control means 26 to send different information to the wheels 16 on the left side 34, than is sent to the wheels 16 on the right side 36. In particular, the left wheels may run at a different speed to the right wheels. This will cause the vehicle to be turned by the relative speeds of the wheels to either side of the vehicle 10. In this example, the control means 26 is operable to vary the relative speeds of the wheels to either side of the vehicle 10, so that the amount by which the vehicle turns can be controlled.

Therefore, the interpretation by the control means 26 of the user instruction 28, to derive wheel speeds and relative speeds, causes the steering system to steer the vehicle by an amount which corresponds with the desired amount instructed by the user.

Steering options The relative speeds of the wheels 16 can be used to create steering, as has been described. In addition, steering can be created by putting the wheels to one side of the vehicle 10 into regenerative braking mode while continuing to drive the wheels to the other side of the vehicle 10 in normal fashion. The braking effect results in a low wheel speed, relative to the driven wheels. In this example, the degree of braking achieved by regenerative braking is dependent on the construction of the motors 32 and in particular, is wholly or substantially independent of the speed of other wheels which are being driven.

Thus, the vehicle 10 may be steered to the right 36 by putting the wheels to the right side 36 into regenerative braking mode so that they turn slowly, and driving the wheels to the left side 34 in a forward direction. If the wheels to the left side 34 are driven relatively quickly, the vehicle 10 will turn sharply to the right 36. If the wheels to the left side 34 are driven less quickly, the vehicle 10 will turn less sharply to the right 36. It will be readily apparent to the reader that if the wheels to the left side 34 are put into regenerative braking mode, the wheels to the right side 36 may be driven more or less quickly to create a sharper or less sharp turn to the left 34.

In another possibility, the user may indicate a desire to reverse the vehicle 10, e.g. by pulling back on the joystick 40. When this situation is identified by the control means 26 from the user instruction 28, a set of control outputs 30 is derived to cause the wheels 16 to be driven in reverse, thus causing the vehicle 10 to travel backwards. In one example, the joystick 40 may be operable to indicate a direction of turn while reversing, by deflecting the joystick 40 to an appropriate position from the central position 42 and generally in the manner described above in relation to turning while moving forward. In particular, it is envisaged that a reverse turn could be achieved by causing the wheels to one side of the vehicle 10 to be placed into regenerative braking mode, with the wheels to the other side of the vehicle 10 being driven in reverse at a speed which dictates the degree of steering achieved.

A further option arises from the use of the spin controls 44, 46. For simplicity, the use of the left spin control 44 will be described for creating a left spin. The right spin control 46 may be used in corresponding manner to create a right spin.

When spin control 44 is depressed, this is reported to the control means 26 as part of the user instruction 28. The control means 26 then derives control outputs 30 to cause a spin in a left direction. This is achieved by providing control outputs 30 which cause the wheels 16 to the left side 34 to be driven in reverse, while the wheels 16 to the right side 36 are driven forward. The result is that the vehicle 10 will turn about its centre, but without any single wheel 16 creating a pivot point on the ground beneath and therefore, in the case of a grass surface, reducing the risk of damage to the grass.

Operation of the spin controls 44, 46 may also be associated with operation of the joystick 40 in order to instruct the spin speed, which can be controlled by the control means 26 setting the relative speed of the forward and reverse wheels 16.

Operation of the control means 26 The operation of the control means 26, as described above, can be summarised by means of the flow diagram of Fig 4. This sequence begins with the operation at 52 of the user input device 38 to create a user instruction 28. The control means 26 receives the user instruction 28 at 54 and interprets the user instruction 28 at steps 56, 58, 60 and 62. At step 56, the control means 26 interprets the user instruction 28 to identify the desired direction of travel as indicated by the user. At step 58, which is optional, the control means 26 interprets the user instruction 28 to identify the desired speed of travel as indicated by the user. At step 60, which is optional, the control means interprets the user instruction 28 to identify the use of a spin control 44, 46 by the user, indicating a desire for the vehicle 10 to spin to the left or to the right. At step 62, which is optional, the control means 26 interprets the user instruction 28 to identify the desired spin speed as indicated by the user, in the event that one of the spin controls 44, 46 has been used.

Having interpreted the user instruction 28, the control means 26 derives appropriate control outputs 30 at step 64, these control outputs 30 being appropriate to cause the vehicle 10 to move forward or in reverse, with steering or spinning as required by the user.

The control means 26 provides these control outputs 30 to the motors 32, at step 66.

Concluding comments Many variations and modifications can be made to the apparatus described above, without departing from the scope of the invention. In particular, many different technologies and configurations could be used for the input controls, control arrangements, drive arrangements etc. A vehicle built in the manner of the examples described above is expected to be simple to operate. In particular, a simple, single user control device (such as a joystick) provides a simple, intuitive arrangement for a user to control the vehicle 10. The user does not need to consider any of the issues relating to the speeds, relative speeds, direction or braking of the wheels. Once the user has instructed the direction, spin etc, the instruction is interpreted by the control means in order to implement the action desired by the user.

In the examples described above, all of the wheels to one side of the vehicle are driven in the same manner (at the same speed and in the same direction, or with regenerative braking). This is expected to provide simplicity in the steering system, with adequate performance. Additional finesse in the steering performance may be provided by providing different wheel speeds along one side of the vehicle, if desired. It is desirable for all wheels to be driven but other arrangements may be suitable. The vehicle has been illustrated as having four wheels, but other arrangements may be suitable.

A steering system of the type described may be incorporated in a vehicle when first manufactured, or may be incorporated retrospectively into an appropriate vehicle. In the latter case, it may be appropriate to provide additional drive units, to provide a separate drive unit for each wheel.

Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

CLAIMS1. A vehicle having fore and aft directions and ground wheels to either side of the vehicle, the system comprising: a control means operable to receive a user instruction indicating a desired direction of travel; the control means being operable to provide control outputs for drive arrangements operable to drive the ground wheels; and the control outputs being derived by the control means from the user instruction and including respective drive information for the corresponding wheel or wheels, to cause the vehicle to be turned by the relative speeds of the wheels to either side of the vehicle.
2. A vehicle according to claim 1, wherein the control means are operable to vary the relative speeds, to set the amount of turn. IC)
3. A vehicle according to claim 1 or 2, wherein the control means are operable to provide a first control output for driven wheels to a first side of the vehicle, and a CO second control output for driven wheels to a second side of the vehicle. r 20
4. A vehicle according to claim 1 or 2, wherein the control means are operable to provide different control outputs for multiple driven wheels to either side of the vehicle.
5. A vehicle according to any preceding claim, wherein the control means are operable to provide control outputs which include speed information.
6. A vehicle according to any preceding claim, wherein the control means are operable to provide control outputs which include braking information for causing 30 braking of the corresponding wheel or wheels.
7. A vehicle according to claim 6, wherein the degree of braking instructed by a control output is independent of the speed of other wheels.
8. A vehicle according to any preceding claim, wherein the system further comprises drive arrangements which include electric motors operable to drive respective wheels.
9. A vehicle according to any preceding claim, wherein the system provides an electric motor for each wheel.
10. A vehicle according to any preceding claim, wherein the control means are operable to provide control outputs which cause regenerative braking of an electric 10 motor or motors.
11. A vehicle according to any preceding claim, wherein the control means are operable to provide sufficient control outputs to cause all wheels to be driven.
12. A vehicle according to any preceding claim, wherein the control means are up vehicle around.

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13. A vehicle according to claim 12, wherein the control means are operable to r 20 distinguish between two spin instructions indicating respective desired spin directions.
14 A vehicle according to claim 12 or 13, wherein the control means are operable in response to a spin instruction to derive control outputs to cause wheels on respective sides of the vehicle to be driven in opposite directions.
15. A vehicle according to any preceding claim, wherein the control means are operable to receive a user instruction which indicates a desired speed of travel, and to derive control outputs causing wheels to be driven at a corresponding speed.operable to receive from a user a spin instruction indicating a desire to spin the
16. A vehicle according to any preceding claim, wherein the system further comprises a joystick operable by a user to create a user instruction.
17. A vehicle according to claim 16, wherein the control means are operable to interpret a direction of deflection of the joystick as indicating a desired direction of travel.18 A vehicle according to claim 16 or 17, wherein the control means are operable to interpret a degree of deflection of the joystick as indicating a desired speed of travel.19. A vehicle substantially as described above, with reference to the 10 accompanying drawings.20. Any novel subject matter or combination including novel subject matter disclosed herein, whether or not within the scope of or relating to the same invention as any of the preceding claims.