STRATEGY

FIELD

This invention relates to the control of speed, acceleration and deceleration of an electric vehicle by way of foot actuated control sensors operable by the vehicle driver and/or passengers.

BACKGROUND

Implementation of electrically powered vehicles for widespread road transportation presents numerous opportunities and challenges in vehicle design and engineering, even more so when considering fully- or semi-autonomous electric vehicles. One of the overriding opportunities is in exploiting potential efficiencies available to electrically powered vehicles. Some of the ways that electric road vehicles can be made to operate in a more efficient manner include: reducing overall vehicle weight; optimising efficiency of conversion from stored energy to vehicle movement (i.e. drivetrain efficiency); optimising vehicle body size and interior space available for a given platform.

As vehicles move into a new era of autonomous control a number of traditional elements of road going vehicle are brought into question. One of these elements is the driver controls of the vehicle and in particular the foot control pedals. Traditionally these pedals were used to mechanically actuate a hydraulic brake cylinder, the clutch and the throttle body of the carburettor. Conventional accelerator pedals have typically had a pedal displacement (or pedal stroke) of about seventy-five millimetres, and brake pedals typically have a displacement between fifty to one-hundred and fifty millimetres, however US military standards allow for brake pedal stroke to be low as thirteen millimetres.

In more recent years the function of these pedals has changed: a clutch pedal is now rarely required, and the accelerator pedal is now generally only connected to an electrical rotary sensor in a by-wire system. The brake pedal has remained relatively unchanged as, in most vehicles, it is still required to actuate a hydraulic master cylinder. However, it is not uncommon for even the brake pedal system to now include an electromechanical actuator for automated braking and a position sensor to provide input for regenerative braking used in most hybrid or electric vehicles. Although the required mechanical function of the pedals has changed the look and feel of these pedals has remained almost entirely unchanged. For highway going vehicles the accelerator input - of a long pedal stroke and low force is very effective for long periods at fixed setting (position/rate), however even this function is typically replaced by cruise control systems.

For low speed city autonomous vehicles the requirement for driver controls is being brought into question. Autonomous concept vehicles are being installed with traditional pedals, no pedals or the foot pedals are being integrated into a hand controlled joystick with full by-wire operation. It can be seen that there is a desire to remove traditional pedals as they consume a significant volume of passenger compartment space and tend to limit the position and orientation of the driver. Traditional foot control pedals also limit the possibility to have clean unbroken surfaces within the vehicle which can detract from both appearance and cleaning of the interior (potentially important in high use autonomous vehicles).

In the known prior art addressing issues of vehicle control pedals, the format and movement of the pedals has for the most part remained unchanged, the primary focus being on keeping a traditional driving experience but with improvements to functionality.

One potential reason for the lack of change to the pedal action is that to date companies have been hesitant to adopt by-wire braking systems and have persisted with the use of brake pedals attached to hydraulic master cylinders. Nevertheless, the use of by-wire braking systems is increasing, although generally the pedal actions in such systems are designed to emulate the pedal of a conventional mechanical/hydraulic coupling arrangement. For example, United States Patent 8,165,747 discloses a pedal system for by-wire vehicle braking that utilizes a conventional style of pedal, wherein the pedal travel and/or pedal reaction force are electrically controlled to provide physical feedback to the user. In particular, the aforementioned document discloses a vehicle operation control apparatus having a mechanical and electrical construction that enables detecting a pedal travel and a pedal effort and electrically controlling an actuator, so as to realize pedal travel corresponding to pedal effort, generates pedal reaction force corresponding to pedal travel, and generates braking force and driving force on the basis of the pedal travel and pedal effort. However, it is possible for lightweight relatively -low speed electric vehicles, particularly those with in-wheel electric motors, to accomplish deceleration/braking through action of the motors themselves, rather than a separated (hydraulic) braking system. This permits a new approach to the functionality and implementation of the vehicle foot-actuated control systems.

In consideration of the above, embodiments of the present invention aim to provide foot actuated vehicle control systems and related methods, particularly insofar as applied to electric road vehicles that predominantly operate autonomously.

SUMMARY

In a first aspect the present invention is a foot actuated vehicle control system comprising a pedal including at least one load/pressure sensing device, said pedal being integrated into or mounted on the vehicle floor structure and responsive to user applied force, with minimal displacement of said sensing device, to generate control signals operative to control motive and/or braking function of the vehicle, in use.

Preferably said load/pressure sensing device comprises at least one strain gauge, or piezo electric device, capacitive load cell, inductive load cell and/or tactile sensor.

Preferably said load/pressure sensing device requires a limited amount of travel, flex or compression to register an input from an operator's foot, in use.

Preferably said pedal functions as a vehicle accelerator, brake or a combination of both accelerator and brake.

Preferably said pedal further includes a haptic feedback device controlled in accordance with the user applied force to provide a sense of movement, change of input parameter or output request to the vehicle motor.

Preferably the addition of a foam or compliant structure is applied to the pedal surface to provide just enough movement to indicate actuation to the user.

Preferably said pedal permits a travel movement less than twelve millimetres. Preferably said displacement of sensing device is less than five millimetres.

Preferably pedals are provided in a plurality of locations within the vehicle cabin, other than the vehicle driver's cockpit.

Preferably said compliant structure laminated into the vehicle structural floor requiring only the addition of the sensors, feedback device, non-structural pedal cover and supporting cabling.

Preferably an electric road vehicle includes a foot actuated vehicle control system according to the first aspect of invention.

In a second aspect the present invention is a foot actuated control system for a vehicle, said control system comprising a pedal including at least one load/pressure sensing device, said pedal being integrated into or mounted on the floor structure of said vehicle and responsive to user applied force, with minimal displacement of said sensing device, to generate control signals operative to control motive and/or braking function of said vehicle, in use, and wherein said load/pressure sensing device requires a limited amount of travel, flex or compression to register an input from an operator's foot, in use, and said pedal includes a haptic feedback device controlled in accordance with the user applied force to provide a sense of movement, change of input parameter or output request to the motor of said vehicle.

In a third aspect the present invention is a foot pedal for use in a control system for a vehicle, said pedal comprising at least one load/pressure sensing device being integrated into or mounted on the floor structure of said vehicle and responsive to user applied force, to generate control signals operative to control motive and/or braking function of said vehicle, and wherein said load/pressure sensing device requires a limited amount of travel, flex or compression to register an input from an operator's foot, in use, and said pedal includes a haptic feedback device controlled in accordance with the user applied force to provide a sense of movement, change of input parameter or output request to the motor of said vehicle.

In particular this invention is aimed at use in low speed electric vehicles and autonomous vehicles under temporary or partial human control where input requirements are different from traditional automobiles whereby these pedals brings additional benefits to the vehicle. These vehicles are typically electrically powered and the motors may have the capability to provide the dominant braking for the vehicle. Such vehicles must provide full by-wire braking capability for the autonomous control system, and thus the motivation to provide full by-wire control of the accelerator and brake to the driver is elevated. The inventors have recognized that where the requirement for the brake pedal to directly actuate a hydraulic master cylinder is removed, for example, the necessity for pedal travel is also removed.

A traditional vehicle accelerator/brake pedal box is likely to consume 200mm or more of cabin space length in order to provide the travel for the pedal and the supporting mechanism. For low speed vehicles operating in cities there is very little period at a fixed point of throttle and a traditional pedal system with high pedal travel comes into question. The application of a little to near zero travel control surface as described herein can provide a suitable vehicle control without any loss of cabin space.

Accordingly the invention provides a foot actuated sensor system for vehicles based on a pressure/force input for the accelerator, brake or combination of both. The invention features reduced complexity, compactness (increased vehicle space) and flexibility and is capable of creating a clean unbroken floor surface within the cabin. The invention comprises one or more load or pressure sensing devices that are integrated into or on the floor structure to form an essentially flat surface for the control of forward and reverse motion of for instance a road vehicle with almost no pedal travel (for example, less than 10mm including any compliant material fitted to the pedal surface, potentially less than 1mm in some embodiments).

An additional novel feature which may be integrated into the system is a haptic feedback device. This device may be used to vibrate with a predefined pattern or frequency profile to indicate a perceived pedal position to the user. As an example the haptic device may vibrate with a given frequency pattern to emulate the feeling of a notched rail as pressure is increased or decreased on the pedal. An improvement might be that as pedal pressure increases the perception of a series of sharp notches might be felt and as pressure is relaxed a more rounded or smooth series of notches might be felt to give the user a sense of movement when in fact there is essentially no movement. Many variations to this feedback are possible with a compact simple vibrating actuator and a suitable high frequency controller as is used in haptic feedback systems. In addition, a signal processing system may be overlayed to better provide smoothing of the control signal, which is particularly useful for the accelerator pedal. This signal processor may apply a digital or analogue model of a mass, spring, friction and damper system with the virtual position of the mass in the model outputted to the control system of the vehicle as the conditioned signal from the accelerator pedal. The model variables of this mass, spring, friction and damper system might be adjusted to provide variation in pedal feel. For instance they might be adjusted to allow slight pressure to come off the pedal whilst holding the same output signal. A further refinement of the system is to include feedback from the vehicle IMU (inertial measurement system) to assist in the smoothing algorithm.

The sensing device for the pedal pressure may comprise one or more load or pressure sensors. These sensors may be overlayed (e.g. configured in series) to provided redundancy or a larger number might be arranged in a mesh pattern as in a tactile pressure sensor to allow for a full map of the foot pressure. With a mesh of sensors redundancy might still be provided by having multiple signal - conditioning units each processing separate signals from different sensors.

From a background of conventional vehicle control pedals, to one skilled in the art the use of a force sensing device such as a load cell with little or no travel for an input device would suggest that the minimal pedal travel would result in poor vehicle controllability by the user. Surprisingly, in the present application this has been shown to not be the case. Additional refinement can be found with the addition of feedback and a control system.

BRIEF DESCRIPTION OF THE DRAWINGS

Further disclosure, objects, advantages and aspects of the present invention may be better understood by those skilled in the relevant art by reference to the following description of preferred embodiments taken in conjunction with the accompanying drawings, which are given by way of illustration only and thus not limitative of the present invention, and in which:

Figure 1 is a diagrammatic illustration of a conventional vehicle control pedal;

Figure 2 is a diagrammatic illustration of a vehicle control pedal according to embodiments of the present invention;

Figure 3 is a diagrammatic illustration of a vehicle seen in overhead view, indicating possible pedal placement locations permitted by embodiments of the invention; and Figure 4 is a block diagram of a vehicle control system according to embodiments of the invention.

DETAILED DESCRIPTION

A conventional form of vehicle control pedal arrangement 10 is diagrammatically illustrated in Figure 1, seen in a side profile. The conventional pedal 14 is pivotally mounted, for example, in relation to the vehicle floor or body structure 12 with a spring bias toward an extended position as seen in solid lines. The pedal 14 is mechanically coupled at 15 to a control mechanism (not seen). In use the vehicle operator is able to depress the pedal 14 by action of a foot 20 whereby the pedal can travel through a displacement 't' to a position indicated in broken lines. Displacement of the pedal 14 results in corresponding movement of the control mechanism (e.g. accelerator cable or brake cylinder) through the mechanical coupling 15. Moreover, the position of the operator's foot 20 in depressing the pedal, along with the spring bias force on the pedal, provides the operator with physical feedback in relation to operation of the pedal and the system controlled thereby. It has heretofore been thought that such displacement travel of the pedal and the physical feedback provided thereby to the user is essential to satisfactory controllability of the vehicle.

Allowing for the pedal travel of a conventional control pedal requires a significant amount of space in the foot-well of the vehicle cabin. Moreover, the mechanical action and couplings of the conventional pedal generally restricts the pedal placement to a single location within the vehicle. For a vehicle that operates, in the majority, autonomously, most of the time all of the vehicle occupants are simply passengers. Therefore, for such vehicles where operator intervention by way of the control pedals is limited the space required for conventional control pedals may be better allocated to foot room for the occupants. Furthermore, it may be desirable for the control pedals to be placed in an alternative location, or indeed multiple locations within the vehicle cabin, to promote flexibility of use.

Accordingly, embodiments of the present invention employ a vehicle control pedal that has little or no pedal travel, and may be integrated into or mounted on the floor or interior body structure of the vehicle cabin. The vehicle control pedal arrangement 30 according to embodiments of the present invention is diagrammatically illustrated in side profile in Figure 2. In this case the pedal 40 comprises one or more load or pressure sensing devices mounted in or to the vehicle floor or body structure 12. In operation, force can be applied to the surface of the pedal 40 by the foot 20 without any substantial movement or travel of the pedal. In order to achieve the little pedal travel, the sensing device has minimal displacement. The degree of force applied by the foot to the pedal (and therefore the sensing device) is sensed and communicated by electrical signals to the vehicle control system in order to control the vehicle motive and/or braking systems accordingly.

It should be understood that in this embodiment, the pedal travel should preferably be less than twenty-five millimetres (25mm), and more preferably it should be less than twelve millimetres (12mm).

In this embodiment the reference to the“sensing device having a minimal displacement” should preferably be a displacement of less than twelve millimetres (12mm) and more preferably less than five millimetres (5mm).

Since the control pedal arrangement of the present invention requires no movement or mechanical coupling, and occupies little or no space, it is possible to place the pedals in alternative and/or multiple locations within the vehicle cabin. This is diagrammatically illustrated in Figure 3 which shows an exemplary vehicle 50, seen in overhead view, having a vehicle body 52 defining a passenger cabin 54. Located within the passenger cabin are front passenger seats 60, 62 and rear passenger seats 64, 66. According to conventional vehicle design the location 70 of the control pedals 80, 82 is in the foot-well in front of the right-hand side front seat 60 (for vehicles designated to drive on the left-hand side of the road). Also according to conventional design, two pedals are provided: a brake pedal (80) positioned adjacent and to the left of an accelerator pedal (82).

As mentioned, for a vehicle that functions predominantly in autonomous or semi-autonomous operation (and typically at relatively low speed), user intervention in control of the vehicle by way of the pedals is occasional and may be desirable from several locations within the passenger cabin. Accordingly, embodiments of the present invention allow for placement of the control pedals in multiple positions as indicated at 72, 74, and 76 whereby a vehicle passenger sitting in any one of the seats 60-66 has access to separate control pedals if necessary. Where multiple sets of control pedals are provided the vehicle control system may selectively discern which control pedals to accept control input signals from according to a particular mode of operation, for example. In addition to pedal location, variations in the pedal layout are also possible. In the conventional style, accelerator and brake pedals may be mounted separately. Alternatively, the accelerator and brake functions may be integrated into a single pedal, responsive to a 'rocking' force operation. In the latter arrangement, the single pedal may be provided with a plurality of sensors providing separate sensing of the toe and heal load. An increase of toe pressure may be used to indicate an acceleration command, a reduction in toe pressure and/or increase in heal pressure to indicate deceleration, and application of both heal and toe pressure at the same time may be used to signify application of an emergency brake procedure.

Figure 4 is a simplified block diagram of a vehicle control system 100 that may be used to implement embodiments of the present invention. In this example, the vehicle has four wheels 192, 194, 196, 198 each incorporating a separate in-wheel electric motor. The in-wheel electric motors are employed to provide torque to the wheels for both acceleration (forward and reverse) and deceleration (braking). For redundancy or increased braking force the vehicle's drive system might also be accompanied by a series of secondary electrically controlled braking devices. A vehicle motor controller 160 includes circuitry to regulate supply of electrical current from a battery pack (not shown) to the electrical motors according to commands from a vehicle systems controller 150. The vehicle systems controller 150 comprises microprocessor -based digital circuitry operating according to program instructions encoded in software or firmware, for example. The systems controller 150 may be adapted to autonomously operate the vehicle, as understood by those skilled in the art, by issuing commands to the motor controller based on predetermined or externally communicated destination and route information in conjunction with data from on-board and external sensors (e.g. GPS, LIDAR, digitally processed camera images, etc.). The systems controller 150 is also responsive to signals derived from the control pedals 110, 120 as described below.

In this exemplary vehicle control system 100 two control pedals are provided, in conventional manner corresponding to accelerator 110 and brake 120. The accelerator pedal 110 includes one or more load sensors 1 12 along with a haptic feedback device 1 14. The brake pedal 120 similarly includes one or more load sensors 122 and with a haptic feedback device 124. Output signals from the load sensors 112, 122 are coupled to be received by signal conditioning circuit 130. The signal conditioning circuit may apply a digital or analogue model of a mass, spring, friction and damper system with the virtual position of the mass in the model outputted to the vehicle systems controller 150 as the conditioned signal from the accelerator/brake pedal. The model variables of this mass, spring, friction and damper system may be adjusted to provide variation in 'pedal feel' as perceived by the operator. For instance they might be adjusted to allow slight pressure to come off the pedal whilst holding the same output signal. A further refinement of the system is to include feedback from the inertial measurement system (part of the vehicle systems controller 150) to assist in the smoothing algorithm.

As discussed above, in the absence of physical pedal travel a haptic feedback device can be used to provide feedback to the operator during use of the pedals 110, 120. Each pedal include such a haptic feedback device (114, 124) which may take the form of an electrical solenoid or vibration device controlled by signals produced by a haptic feedback controller 140. The haptic feedback device may be controlled so as to vibrate with a predefined pattern or frequency profile to indicate a perceived pedal position to the user. For instance, the haptic device may be controlled to vibrate with a given frequency pattern to emulate the feeling of a notched rail as pressure is increased or decreased on the pedal. As pedal pressure increases the perception of a series of sharp notches might be produced, and as pressure is relaxed a more rounded or smooth series of notches might be produced, giving the user a sense of pedal movement when in fact there is essentially no actual displacement of the pedal. Many variations to this feedback are possible with compact simple vibrating actuator and a suitable high frequency controller as is used in haptic feedback systems.

Load sensors (e.g. 112, 122) for use in embodiments of the invention may be selected from a range of devices such as strain gauge or piezo electric device or capacitive, inductive or tactile sensor. For redundancy purposes multiple sensors would normally be mounted in the same location in a stacked arrangement to provide multiple signals and signal processing units for comparison by the vehicle control system. A convoluted band around the pedal may be built into the surrounding structure to allow for a small amount of movement to allow the sensors requirement of a limited amount of travel or flex to register an input. However, any 'travel' of the pedal or sensor permitted by the mounting arrangement or otherwise is not determinative of the output from the sensor, which is based on applied force rather than pedal displacement. To further increase the sense of ‘feel’ to the user experience, a foam like structure may be added to the top of the pedal to indicate the presence of a control surface and provide a small amount of compliance. As noted, the sensors might be accompanied by a haptic feedback device to emulate a sense of movement or indicate the level of pressure registered on the pedal. Another embodiment of the invention would be that the supporting structure for the pedals is formed directly into the vehicle interior surface. The sensor element could then be fitted directly to this surface without the need for additional components and provide a completely uninterrupted sealed surface at the pedal.

For an autonomous vehicle there maybe additional benefit with the ability to locate a number of sensors systems in a number of position in or around the vehicle floor (bottom of a seat or foot rest). Having a number of locations could allow input from a passenger or driver and the control system of the vehicle could interpret this input as required for the situation (e.g. indication of desired location to come to rest in front of a broadly/vaguely specified location or picking a person up for a large group of people such as airport waiting areas). Having a direct input device is likely to be more suitable than voice commands in many cases. A similar device that is reduced in size and load rating could be mounted into the doors to be hand operated (similar to an electric window winder control in style).

To summarise, some key features that are provided, enabled or facilitated by embodiments of the present invention include:

• Flat Surface

• Clean Surface

• Solid state operation (high durability)

• Multiple locations in the vehicle

• Potential for passenger interaction or interaction from non-conventional seating orientation

• In Autonomous mode - ability to indicate to slow or stop vehicle

• Can be directly built into the vehicle floor structure with minimal additional components/cost

• Thin element for easy location

• Multiple sensor in accelerator for combined accelerator and brake (non-emergency)

• Multiple sensors could be used - mixed sensor type. An addition/variation is a mix of pressure and position (X,Y rather than rotation) for added control

• Sensor could be pressure or position or mixed types combined

• Could be placed on floor or potential for other locations

• Feedback via a haptic device can improve the functionality

• Signal processing is useful to smooth the signal and adjust“pedal feel” • Significantly increased passenger compartment space due to both the removal of the volume required for traditional pedal travel in the compartment and also removal of the components being actuated such as the brake master cylinders in front of the footwell

A vehicle testing rig equipped with an embodiment of the invention utilising a strain gauge sensor on a pedal fitted with a 10mm thick foam surface has undergone trials on a vehicle dynamometer and tested by numerous people. Those who participated in the trials reported that they were surprised by how natural the resulting driving experience was. Without wishing to be bound by theory, one possible contributing factor in this surprising result is thought to derive from characteristics of the electric vehicle, insofar as the drive electric motor(s) provides near instantaneous feedback to the user control input without the delay found in an internal combustion engine.

The structure and implementation of embodiments of the invention has been described by way of non-limiting example only, and many additional modifications and variations may be apparent to those skilled in the relevant art without departing from the spirit and scope of the invention described.

Any discussion of documents, devices, acts or knowledge in this specification is included to explain the context of the invention. It should not be taken as an admission that any of the material forms part of the prior art base or common general knowledge in the relevant art in Australia or elsewhere on or before the priority date of the disclosure and claims herein.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.