Improved downshift response

Abstract

Aspects and embodiments of the present disclosure relate to a control system (100), an automatic transmission system (10), a vehicle (1), a method (300), and computer readable instructions for controlling an automatic transmission (12) of a vehicle (1), including, in a first mode, controlling (310) the automatic transmission (12) according to a first shift logic (400), a first shift logic (400) defining downshift thresholds for the speed parameter as a function of the accelerator input, where each downshift threshold is defined by a unique function; controlling (350), in a second mode, the automatic transmission (12) according to a second shift logic (500) defining a downshift threshold of the speed parameter as a function of the accelerator input, where at least two downshift thresholds are defined by a common function; receiving (320) a signal indicative of an increase rate of the accelerator input; and switching from the first mode to the second mode in accordance with the rate of increase of the accelerator input exceeding the threshold rate and regardless of whether a downshift threshold of the first shift logic (400) is crossed.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to improved downshift response. Aspects of the invention relate to control systems, automatic transmission systems, vehicles, methods and computer readable instructions. BACKGROUND

[0002] It is known to equip vehicles with automatic transmissions. Automatic transmissions do not require input from a driver to shift. Instead, gear management is provided to determine when it is appropriate to shift under a given set of circumstances and what gear it is appropriate to adopt.

[0003] In some circumstances, gear management can quickly determine a plurality of appropriate gears in succession. Adopting each of these gears can compromise the acceleration performance of the vehicle. SUMMARY

[0004] Aspects and embodiments of the invention provide control systems, automatic transmission systems, vehicles, methods and computer readable instructions as claimed in the appended claims.

[0005] According to an aspect of the invention, there is provided a control system for an automatic transmission of a vehicle, the control system comprising any one or more of the features described herein.

[0006] According to an aspect of the invention, there is provided a control system for an automatic transmission of a vehicle. The control system comprises one or more controllers. The control system is configured to:

[0007] in a first mode, control the automatic transmission in accordance with a first shift map defining downshift thresholds of a speed parameter as a function of accelerator input, wherein each downshift threshold is defined by a unique function;

[0008] in a second mode, control the automatic transmission in accordance with a second shift map defining downshift thresholds of a speed parameter as a function of accelerator input, wherein at least two downshift thresholds are defined by a common function;

[0009] receive a signal indicative of an increase rate of accelerator input; and

[0010] switch from the first mode to the second mode in dependence on the increase rate of accelerator input exceeding a threshold rate and irrespective of whether a downshift threshold of the first shift map is being crossed.

[0011] An advantage of defining at least two downshift thresholds by a common function is that these at least two downshift thresholds can be crossed simultaneously, resulting in skipping of intermediate gear ratios. This results in faster adoption of lower gear ratios, in which case there is more mechanical advantage to help the vehicle accelerate. By triggering the switch to the shift logic defining at least two downshift thresholds by a common function based on the rate of increase of accelerator input rather than the crossing of a downshift threshold, the vehicle acceleration can be particularly responsive to sporty accelerator inputs.

[0012] Optionally, the control system is configured to determine the threshold rate based on a current accelerator input.

[0013] Optionally, the control system is configured to determine the threshold rate based on a difference between a current accelerator input and a rolling average of accelerator input.

[0014] Optionally, the control system is configured to determine the threshold rate based on a gear ratio currently proposed by the first shift logic.

[0015] Optionally, the threshold rate is higher than another threshold rate associated with switching out of the first mode when a downshift threshold in the first shift logic is crossed.

[0016] Optionally, the at least two downshift thresholds defined by the common function represent a downshift between two non-adjacent gear ratios, which can be performed as a direct shift by the automatic transmission hardware.

[0017] An advantage of this is that fast shifting is achieved while skipping intermediate gear ratios, and thus lower gear ratios are achieved more quickly, and increased acceleration can be achieved more quickly, thus providing improved responsiveness.

[0018] Optionally, at least two other downshift thresholds in the second shift logic are defined by another common function.

[0019] Optionally, at least two downshift thresholds defined by the common function in the second shift logic have a higher value of the speed parameter for a range of accelerator inputs than the corresponding downshift threshold in the first shift logic.

[0020] Optionally, at least some of the downshift thresholds in the second shift logic have a higher value of the speed parameter for a range of accelerator inputs than the corresponding downshift threshold in the first shift logic.

[0021] An advantage of this is that lower gear ratios can be maintained for longer to maximise the mechanical advantage from lower gear ratios, thus providing more responsive vehicle acceleration.

[0022] Optionally, the at least two downshift thresholds defined by the common function do not change with accelerator input.

[0023] Optionally, at least some of the downshift thresholds in the second shift logic do not change with accelerator input.

[0024] This has the advantage that the triggering of the corresponding downshift can be based entirely on the value of the speed parameter and can be set to provide the largest possible acceleration gear for a range of values of the speed parameter.

[0025] According to another aspect of the application, there is provided an automatic transmission system comprising a control system.

[0026] According to another aspect of the application, there is provided a vehicle comprising an automatic transmission system.

[0027] According to another aspect of the application, there is provided a method of controlling an automatic transmission of a vehicle, the method comprising:

[0028] In the first mode, the automatic transmission is controlled in accordance with a first shift logic which defines downshift thresholds for the speed parameter as a function of accelerator input, wherein each downshift threshold is defined by a unique function;

[0029] In the second mode, the automatic transmission is controlled in accordance with a second shift logic which defines downshift thresholds for the speed parameter as a function of accelerator input, wherein at least two of the downshift thresholds are defined by a common function;

[0030] receiving a signal indicative of an increase rate of accelerator input; and

[0031] switching from the first mode to the second mode in dependence on the increase rate of accelerator input exceeding a threshold rate and irrespective of whether the downshift threshold of the first shift logic is being crossed.

[0032] According to another aspect of the application, there are provided computer readable instructions which, when executed by a computer, are arranged to perform any one or more of the methods described herein. According to another aspect of the application, there is provided a non-transitory computer readable medium comprising computer readable instructions which, when executed by one or more electronic processors, cause the one or more electronic processors to perform any one or more of the methods described herein.

[0033] Within the scope of this application, it is expressly intended that the various aspects, embodiments, examples and alternatives set forth in the preceding paragraphs, in the claims, and / or in the following description and drawings, and in particular the various features taught herewith, can be employed alone or in any combination(s) thereof. That is, the various embodiments can be combined with one another to form additional embodiments, and all of the features and / or embodiments described herewith can be employed in any combination(s). The applicant reserves the right to change any originally claimed feature of the application in its entirety or part at any time during the pendency of this application without the consent of the Examiner. Applicant reserves the right to amend this application to expressly recite any element of any claim that is implicitly or explicitly described or referenced herein, including any element of any claim that is implicitly or explicitly described or referenced in the following description and drawings. BRIEF DESCRIPTION OF DRAWINGS

[0034] One or more embodiments of the application will now be described, by way of example only, with reference to the accompanying drawings in which:

[0035] Figure 1 An example of a vehicle is shown;

[0036] Figure 2 An example of at least a portion of a powertrain of a vehicle is shown;

[0037] Figure 3 An example of a control system is shown;

[0038] Figure 4 An example of a non-transitory computer readable storage medium is shown;

[0039] Figure 5 An example of a method is shown;

[0040] Figure 6A And Figure 6B An example of downshift and upshift thresholds of a shift logic is shown;

[0041] Figure 7A And Figure 7B An example of downshift and upshift thresholds of another shift logic is shown;

[0042] Figure 8 Yet another example of a method is shown;

[0043] Figure 9 An example of a downshift threshold of a shift logic is shown;

[0044] Figure 10A And Figure 10B An example of downshift and upshift thresholds of another shift logic is shown;

[0045] Figure 11Yet further examples of methods are shown; and

[0046] Figure 12 Examples of a further method are shown. DETAILED DESCRIPTION

[0047] Reference is made herein to the accompanying drawings Figure 1 A vehicle 1 according to an embodiment of the application is described. In some examples, but not necessarily all examples, the vehicle 1 is a passenger vehicle, also known as a passenger car or car. In other examples, embodiments of the application can be implemented for other applications, for example commercial vehicles.

[0048] Figure 2 Examples of at least part of the powertrain of the vehicle 1 are shown schematically.

[0049] In this example, the vehicle 1 comprises a propulsion system 22 comprising a plurality of torque sources 24, 26 selectively operable for the purpose of providing drive torque for accelerating the vehicle 1.

[0050] A torque source refers to a prime mover, for example an internal combustion engine, an electric machine such as a traction electric machine, or the like.

[0051] In the shown example, the propulsion system 22 comprises two torque sources 24, 26. The first torque source 24 is an internal combustion engine (“engine”). The second torque source 26 is an electric machine.

[0052] The electric machine 26 is an electric motor arranged to convert electrical energy into kinetic energy in the form of mechanical torque, and vice versa. The electric motor 26 can be an alternating current induction electric motor or a permanent magnet electric motor or other type of electric motor. The electric machine 26 is a traction electric machine configured to implement an electric mode comprising at least pure electric drive. That is, the electric machine 26 can drive the vehicle independently (without the engine).

[0053] The propulsion system 22 is configured to operate in a plurality of predefined operating modes. These include at least an electric mode and a parallel hybrid mode.

[0054] In the electric mode (also referred to as electric vehicle (EV) mode or pure electric mode), the vehicle 1 is propelled by torque generated by the electric machine 26 only. The engine 24 can be switched off (in a non-running state) so that no fuel is consumed, but the engine 24 can still rotate if not disconnected from the wheels 34. The engine 24 can alternatively be switched on, but only for the purpose of generating electrical energy and not connected to the torque path to the wheels 34.

[0055] In the parallel hybrid mode, the vehicle 1 is propelled by torque generated by both the engine 24 and the electric machine 26.

[0056] The predefined operating modes can also include a pure engine mode in which the vehicle 1 is propelled only by torque generated by the engine 24 and there is no electric propulsion.

[0057] The transitions between the predefined operating modes of the propulsion system 22 include switching on or off one of the torque sources 24, 26 so that it outputs or does not output torque, respectively. In some examples, the transitions between the predefined operating modes also include mechanically connecting (coupling) or disconnecting one of the torque sources 24, 26 to / from the transmission system. A coupling clutch 25 is provided to mechanically connect and disconnect the engine 24 from the transmission system. It will be appreciated that the transitions between the predefined operating modes are not instantaneous. When the propulsion system 22 is transitioning between the predefined operating modes, its mode state is “transitioning”.

[0058] The vehicle 1 comprises an automatic transmission system 10 including an automatic transmission 12 and a control system 100, for example a transmission control unit / module for controlling the automatic transmission 12.

[0059] The automatic transmission 12 includes a launch device 14 which transmits torque output by the operating torque source 24, 26 of the propulsion system 22 to the transmission input shaft 18. The launch device 14 can be a hydrodynamic coupling, for example a torque converter, or one or more automatically actuated friction clutches as found for example in a dual clutch transmission.

[0060] The automatic transmission 12 also includes a gearset, labelled 16, and accompanying shift mechanisms. The gearset 16 includes a plurality of gears which are selectively couplable to different gear trains to achieve a plurality of gear ratios between the transmission input shaft 18 and the transmission output shaft 20. Each gear can have a corresponding clutch configured to couple the gear (directly or indirectly) to the transmission output shaft 20.

[0061] The clutches and their actuators form the shift mechanisms. The actuators can be solenoids.

[0062] The shift mechanisms are controlled to establish a selected gear ratio in dependence on control signals output by the control system 100. The control system 100 can determine which clutches are involved in shifting to the selected gear ratio and determine how pressure at the clutches should be controlled to establish the selected gear ratio. The control system 100 can then directly control the actuators associated with these clutches to increase or decrease pressure at these clutches as required.

[0063] The control system 100 is also able to control actuation of the launch device 14.

[0064] The transmission output shaft 20 is connected to a final set of gears 32, such as a pinion that meshes with a ring gear, to transmit torque to the wheel axle and thus the vehicle wheels 34.

[0065] To store electrical energy for use in motor 26, vehicle 1 includes an energy storage device 28. The energy storage device 28 may be a traction battery. The traction battery 28 provides the nominal voltage required by a power user, such as motor 26.

[0066] The traction battery 28 can be a high-voltage battery. The traction battery 28 can have the voltage and capacity to support continuous pure electric drive. The traction battery 28 can have a capacity of several kilowatt-hours to maximize driving range. The capacity can be tens of kilowatt-hours, or even more than one hundred kilowatt-hours.

[0067] Although the traction battery 28 is shown as a single entity, the function of the traction battery 28 can be achieved by using multiple small traction batteries in different locations of the vehicle 1.

[0068] Inverter 30 converts the DC output of traction battery 28 to the AC input required by motor 26.

[0069] Based on the above description of vehicle 1, it should be understood that vehicle 1 is a fully hybrid electric vehicle (HEV). However, in some examples, vehicle 1 may be coupled with, for example, Figure 2 The vehicles shown are different. Vehicle 1 can be a mild HEV, an internal combustion engine vehicle (ICEV), or another vehicle.

[0070] The mild HEV does not have a pure electric propulsion mode, but the motor 26 can be configured to provide assistance, such as increasing the output torque of the engine 24. The power of the motor 26 is insufficient to drive the vehicle 1 on electric power only.

[0071] The ICEV is powered solely by the engine (24). Any onboard motors are used only as starter generators.

[0072] At least some of the disclosures presented herein can be applied to any of these vehicles.

[0073] Figure 3 An example of a control system 100 for an automatic transmission 12 in vehicle 1 is shown. The control system 100 includes one or more controllers 102.

[0074] The control system 100 is configured to receive data from multiple sensors 116 or other control systems. The control system 100 is configured to receive data on the rate of increase of the accelerator input, or accelerator input data, from, for example, an accelerator pedal sensor, or a system that processes the output of the accelerator pedal sensor to determine the torque requested by the propulsion system 22, or from an automated driving system (ADS) or advanced driver assistance system (ADAS), based on which the control system 100 can determine the rate of increase of the accelerator input. The control system 100 may also be configured to receive speed parameter data, such as measurements from a crank position sensor, transmission speed sensor, wheel speed sensor, etc. The control system 100 may also be configured to receive data on the current road load, or data that can be calculated from it, such as estimated vehicle mass, estimated gradient (road gradient), estimated aerodynamic drag, and / or estimated rolling resistance.

[0075] The control system 100 is configured to determine when to switch the mode controlling the automatic transmission 12, thereby changing the effective shift logic. The control system is configured to switch modes accordingly.

[0076] The control system 100 is configured to control the automatic transmission 12 according to valid shift logic by: determining a target gear ratio using valid shift logic; and, for example, outputting a control signal including instructions for initiating a shift to the target gear ratio (e.g., by controlling the hardware of the automatic transmission 12, and particularly the shift mechanism for establishing the gear ratio).

[0077] like Figure 3 The control system 100 shown includes a controller 102, but it should be understood that this is illustrative only. The controller 102 includes a processing device 106 and a memory device 108. The processing device 106 may be one or more electronic processing devices 106 operably executing computer-readable instructions. The memory device 108 may be one or more memory devices 108. The memory device 108 is electrically connected to the processing device 106. The memory device 108 is configured to store instructions, and the processing device 106 is configured to access the memory device 108 and execute the instructions stored on the memory device 108.

[0078] The controller 102 includes input devices 112 and output devices 114. The input devices 112 can include electrical inputs 112 of the controller 102. The output devices 114 can include electrical outputs 114 of the controller 102. The controller 102 can have an interface 104 that includes electrical inputs / outputs, I / O, 112, 114, or electrical inputs 112, or electrical outputs 114, for receiving information and interacting with external components. The inputs 112 are arranged to receive a plurality of signals from a plurality of sensors 116 or other control systems. At least one signal is an electrical signal indicative of an increasing rate of accelerator input. Other received signals can include electrical signals indicative of a speed parameter and one or more electrical signals indicative of a road load. The outputs 114 are arranged to output control signals including instructions to initiate a gear shift.

[0079] Figure 4 A non-transitory computer readable storage medium 200 is shown that includes instructions (computer software).

[0080] It will be appreciated that the controller 102, or each controller 102, can comprise a control unit or computing device having one or more electronic processors (e.g. microprocessors, microcontrollers, application specific integrated circuits (ASICs) etc.) and can comprise a single control unit or computing device, or alternatively, different functions of the controller 102, or each controller 102, can be embodied or hosted in different control units or computing devices. As used herein, the term “controller”, “control unit” or “computing device” will be understood to include a single controller, control unit or computing device, as well as multiple controllers, control units or computing devices operating in concert to provide the required control functionality. A set of instructions can be provided which, when executed, cause the controller 102 to implement the control techniques described herein, including some or all of the functionality required by the methods described herein. The set of instructions 110 can be embedded in the one or more electronic processors 106 of the controller 102; or alternatively, the set of instructions 110 can be provided as software to be executed in the controller 102. A first controller or control unit can be implemented in software running on one or more processors. One or more other controllers or control units can be implemented in software running on one or more processors (optionally the same one or more processors as the first controller or control unit). Other arrangements are also useful.

[0081] The electronic processor 106, or each electronic processor 106, can comprise any suitable electronic processor (e.g., microprocessor, microcontroller, ASIC, etc.) configured to execute electronic instructions 110. The electronic memory device 108, or each electronic memory device 108, can comprise any suitable memory device and can have stored therein or thereon various data, information, thresholds, lookup tables, or other data structures and / or instructions. In embodiments, the memory device 108 has stored therein or thereon information and instructions for software, firmware, programs, algorithms, scripts, applications, etc. that can control all or a portion of the methods described herein. The processor, or each electronic processor 106, can access the memory device 108 and execute and / or use these or those instructions and information to implement or perform some or all of the functions and methods described herein.

[0082] The at least one memory device 108 can comprise a computer readable storage medium (e.g., non-transitory or non-transient storage medium) that can include any mechanism for storing information in a form readable by a machine or electronic processor / computing device. Examples of such forms include, but are not limited to: read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM and EEPROM); flash memory; or electrical or other types of medium for storing such information / instructions.

[0083] Figure 5 An example of a method 300 of controlling an automatic transmission 12 of a vehicle 1 is shown. The method 300 can be performed by Figure 3 The control system 100 shown. In particular, the memory 108 can comprise computer readable instructions 110 that, when executed by the processor 106, perform the method 300.

[0084] The method 300 involves entering a mode of control of the automatic transmission 12 in which its response time to a rapid increase in accelerator input is improved.

[0085] The automatic transmission is controlled in accordance with a shift logic that is valid at a given time.

[0086] The shift logic is used to determine a target gear ratio of the automatic transmission 12 based on a speed parameter and an accelerator input.

[0087] The speed parameter can be any speed parameter suitable to enable determination of a gear ratio in which the automatic transmission 12 is placed.

[0088] For example, the speed parameter can be a speed parameter of the vehicle 1, such as its longitudinal speed (the longitudinal direction being defined by an axis between the front and the rear of the vehicle 1 ). Alternatively, the speed parameter can be a speed parameter of a powertrain component, such as the rotational speed of one or more of the wheels 34, or the rotational speed of the transmission output shaft 20, or the rotational speed of the transmission input shaft 18 (which can be measured in terms of the rotational speed of the turbine of the torque converter 14), or the rotational speed of the engine 24 and / or the electric machine 26. In some examples, the speed parameter can be a ratio between those parameters, in particular those relating to the speed on either side of the gear set 16, such as the ratio between the longitudinal speed of the vehicle and the engine / electric machine speed or the ratio between the wheel speed and the transmission input shaft speed.

[0089] In some examples, the speed of the transmission output shaft 20 can be used, as it can be measured within the automatic transmission system 10 and therefore network latency and communication issues do not affect the signal indicative of it.

[0090] The accelerator input can depend on, for example, the accelerator pedal depression (APD) or autonomous driving torque demand from an autonomous driving system (ADS) or advanced driver assistance system (ADAS). The accelerator input can be indicative of the torque requested or to be requested by the propulsion system 22.

[0091] The shift logic defines a plurality of regions of the parameter space spanned by the speed parameter and the accelerator input.

[0092] Each of the regions of the parameter space defined by the shift logic is associated with a different gear ratio. The highest gear ratio provides the fastest transmission output speed for a given transmission input speed. The lowest gear ratio provides the slowest transmission output speed for a given transmission input speed. Upshifting increases the gear ratio, while downshifting decreases the gear ratio.

[0093] The region associated with the highest gear ratio comprises a low speed parameter boundary (downshift threshold) as a function of the accelerator input.

[0094] The region associated with the lowest gear ratio comprises a high speed parameter boundary (upshift threshold) as a function of the accelerator input.

[0095] Each of the regions associated with the intermediate gear ratios comprises a low speed parameter boundary (downshift threshold) as a function of the accelerator input and a high speed parameter boundary (upshift threshold) as a function of the accelerator input.

[0096] The functions defining the shift (change of transmission ratio) thresholds can be specified in various forms. For example, each of the functions can be specified by one or more mathematical formulae (e.g. in the case of piecewise functions). Alternatively, each of the functions can be specified by listing the function values, for example in a table or array. The table or array can give the function values at specific values of accelerator input. If function values associated with intermediate values of accelerator input are required, interpolation can be used to estimate the function values. The function values at specific values of accelerator input are referred to as "shift points". Shift points associated with downshifts are referred to as "downshift points". Shift points associated with upshifts are referred to as "upshift points".

[0097] When the current value of the accelerator input and the current value of the speed parameter describe a point within the defined parameter space that is not within the region associated with the current transmission ratio, a transmission ratio different from the current transmission ratio can be suggested by the active shift logic. The suggested transmission ratio is the transmission ratio associated with the region in which the point lies.

[0098] For each transmission ratio, the region associated with that transmission ratio can at least partially overlap with the region of the nearest neighbouring transmission ratio (in terms of size).

[0099] If the point described by the current value of the accelerator input and the current value of the speed parameter lies within an overlap region between two or more regions, the suggested transmission ratio will depend on the direction of entry into the region.

[0100] Controlling the automatic transmission 12 in accordance with the active shift logic comprises shifting from the current transmission ratio to a target transmission ratio based on the transmission ratio suggested by the active shift logic. This can be done by receiving an input indicative of the speed parameter and an accelerator input; and outputting a control signal comprising an instruction to initiate a shift, for example by controlling hardware of the automatic transmission 12, in particular a shift mechanism for establishing a transmission ratio.

[0101] However, it will be appreciated that the transmission ratio suggested by the active shift logic can also be subject to shift range availability limitations prior to final arbitration of the target transmission ratio. For example, the number of transmission ratios that can be skipped when shifting from the current transmission ratio to the target transmission ratio can be limited.

[0102] The transmission ratio suggested by the active shift logic can also be subject to shift inhibition conditions prior to final arbitration of the target transmission ratio. Examples of shift inhibition conditions include, but are not limited to:

[0103] A defined period of time has elapsed since the completion of a previous shift;

[0104] An advanced driver assistance system (ADAS) feature, such as adaptive cruise control, is active;

[0105] driving downhill, or at least driving downhill above a threshold gradient;

[0106] a rate of decrease of accelerator input exceeds a threshold rate;

[0107] turning, or at least turning above a threshold based on lateral acceleration;

[0108] driving in reverse;

[0109] a propulsion system of the vehicle transitions between predefined operating modes;

[0110] determining different target gear ratios based on changes in at least one of a speed parameter, an accelerator input, or an active shift logic; and

[0111] a rate of decrease of powertrain torque exceeds a threshold rate.

[0112] Returning specifically to the method 300, control of the automatic transmission 12 begins in a first mode at block 310. The first mode can be a mode used in normal driving.

[0113] In the first mode, the automatic transmission 12 is controlled according to a first shift logic 400, an example of which is shown in Figure 6A and 6B In the first mode, the first shift logic 400 is the active shift logic.

[0114] Each of the low speed parameter boundaries (downshift thresholds) in the first shift logic 400 is unique. The first shift logic 400 defines a unique set of downshift points for each downshift. In some examples, the low speed parameter boundaries (downshift thresholds) do not overlap or intersect with each other. None of the sets share any downshift points. The downshift points can be calibrated so that a downshift is recommended when the powertrain reaches a maximum possible torque at a given speed parameter value.

[0115] It can also be the case that one high speed parameter boundary (upshift threshold) in the first shift logic 400 does not overlap or intersect with each other. None of the sets share any upshift points.

[0116] Depending on the current operating conditions, different first shift logics can be active at different times during operation in the first mode. Thus, in the first mode, the shift thresholds can change as the operating conditions change.

[0117] During operation in the first mode, the first shift logic 400 valid at a given moment in time can be obtained from a set of first shift logics stored in the memory 108 of the control system 100. The set of first shift logics stored in the memory 108 covers a limited, discrete set of specific operating conditions involving both internal and external factors. If the current operating conditions do not match these shift logics, an interpolation can be performed between stored first shift logics (stored first shift logics associated with similar but different operating conditions than the current operating conditions) to generate a first shift logic suitable for the current operating conditions. Additionally or alternatively, other non-interpolative modifications can be applied to the shift thresholds to take into account the current operating conditions.

[0118] During operation in the first mode, the first shift logic 400 valid at a given moment in time can be based on the current road load. The road load reflects the driving resistance calculated from weight, slope, etc. The road load can be calculated from one or more estimated vehicle mass, estimated slope (road gradient), estimated aerodynamic drag, and estimated rolling resistance, all of which can be indicated by signals received by the control system 100. Alternatively, the road load can also be indicated directly by signals received by the control system 100.

[0119] Different first shift logics in the set of first shift logics stored in the memory 108 can be associated with different road loads. When different road loads are encountered, different ones of these first shift logics can be selected and used. Different ones of these first shift logics can be specifically calibrated to compensate for different road loads, typically more aggressive curves are employed for higher road loads, where the shift is triggered at higher speed parameter values.

[0120] If one of the set of first shift logics is associated with the current road load, it can be selected as the valid shift logic. If not, the valid shift logic can be obtained by interpolating between at least two shift logics in the set of first shift logics (associated with road loads similar to the current road load), for example a pair of first shift logics associated with the road load interval in which the current road load lies.

[0121] During operation in the first mode, the first shift logic 400 valid at a given moment in time can be obtained from the set of first shift logics, further depending on one or more other current operating conditions in addition to the current road load, for example: air pressure (taking into account both altitude and temperature), driving style of the driver, operating mode of the propulsion system 22, or reduction in powertrain capability, if any.

[0122] Block 320 of the method 300 includes receiving a signal indicative of an increasing rate of accelerator input.

[0123] The signal can be an accelerator input gradient (rate of change) signal, or can be a series of accelerator input signals, from which the rate of change can be determined from their change over time.

[0124] Block 330 of the method 300 includes determining whether the increasing rate of accelerator input exceeds a threshold rate.

[0125] If the increasing rate of accelerator input exceeds the threshold rate (the "yes" path from block 330), the method 300 proceeds to block 340. Block 340 includes switching control of the automatic transmission 12 from the first mode to a second mode.

[0126] The increasing rate of accelerator input exceeding the threshold rate can be the only requirement to trigger the switch from the first mode to the second mode. There is no need to cross a downshift threshold of the first shift logic 400 to trigger the switch from the first mode to the second mode.

[0127] If the increasing rate of accelerator input does not exceed the threshold rate (the "no" path from block 330), the second mode is not entered. In some examples, operation in the first mode continues. In other examples, operation in the first mode can continue, or can switch to a third mode, if the increasing rate of accelerator input exceeds another, lower threshold rate. Further description of the third mode and the other, lower threshold rate is provided below. Figure 8 Further description of the third mode and another, lower threshold rate.

[0128] In the second mode, the automatic transmission 12 is controlled according to a second shift logic 500, an example of which is shown in Figure 7A and Figure 7B In the second mode, the second shift logic 500 is the active shift logic.

[0129] Accordingly, after the mode switch at block 340, block 350 includes controlling the automatic transmission 12 according to the second shift logic 500. Accordingly, the mode switch includes changing the active shift logic. However, while operating in the second mode, the active shift logic does not change. The automatic transmission 12 is controlled according to the same second shift logic 500 until the second mode is exited.

[0130] At least some of the low speed parameter boundaries (downshift thresholds) in the second shift logic 500 are shared. At least two downshift thresholds are defined by a common function. Thus, the second shift logic 500 can define at least two downshifts according to a set of shared downshift points. In some examples, at least two other downshift thresholds are defined by another common function. Thus, the second shift logic 500 can define at least two other downshifts according to another set of shared downshift points.

[0131] The downshift thresholds of the second shift logic 500 can not change with changes in road load. The second mode can not involve using different second shift logics that are calibrated to compensate for different road loads based on the current road load. Thus, during operation in the second mode, the downshift thresholds do not change with changes in road load.

[0132] In contrast to the low speed parameter boundaries (downshift thresholds), each of the high speed parameter boundaries (upshift thresholds) in the second shift logic 500 can be unique. The second shift logic 500 can define a set of unique upshift points for each upshift. In some examples, the high speed parameter boundaries (upshift thresholds) do not overlap or intersect with each other. None of these sets share any upshift points. In other examples, at least some of the high speed parameter boundaries (upshift thresholds) can coincide with each other for a range of accelerator inputs. For example, at low accelerator inputs, the upshift points can be shared between at least two upshifts. At higher accelerator inputs, the upshift points associated with these at least two upshifts diverge.

[0133] Figure 6A An example of the downshift thresholds of the first shift logic 400 is shown. The speed parameter ω is shown on the x-axis with respect to the accelerator input a on the y-axis. In this example, the first shift logic 400 is for an eight-speed transmission, and accordingly, seven downshift thresholds are shown. The rightmost line of these lines represents the downshift threshold for triggering a downshift from the eighth gear (highest transmission ratio), and the leftmost line of the lines represents the downshift threshold for triggering a downshift to the first gear (lowest transmission ratio). The lines in between represent the downshift thresholds for triggering a downshift from the seventh gear down to the second gear, in turn.

[0134] Figure 6B An example of the upshift thresholds of the same first shift logic 400 is shown. The speed parameter ω is shown on the x-axis with respect to the accelerator input a on the y-axis. Seven upshift thresholds are shown. The leftmost line of these lines represents the upshift threshold for triggering an upshift from the first gear (lowest transmission ratio), and the rightmost line of the lines represents the upshift threshold for triggering an upshift to the eighth gear (highest transmission ratio). The lines in between represent the upshift thresholds for triggering an upshift from the second gear up to the seventh gear, in turn.

[0135] focus on Figure 6A A number of rapid increases in accelerator input are shown for different starting values of the accelerator input and for different values of the speed parameter for which the increases are made. These are shown in the parameter space plot as vertical arrows 402 to 416. They are each of the same length, indicating the same increase magnitude, in other words the same increase rate, in a given time. This increase rate exceeds the threshold rate and so triggers the switch from the first mode in which the first shift logic 400 is active to the second mode in which the second shift logic 500 is active.

[0136] The points within the parameter space described by the start and end of the arrows 402 to 416 represent the gear ratios proposed or to be proposed by the first shift logic 400 before and after the accelerator input is increased. These can be subject to other limitations, so these represent the current and target gear ratios when the automatic transmission 12 is controlled according to the first shift logic 400.

[0137] Arrow 402 crosses one downshift threshold and represents a shift from the fifth gear to the fourth gear as proposed according to the first shift logic 400. Arrow 404 does not cross any downshift threshold and so represents no shift from the seventh gear being proposed. Arrow 406 crosses two downshift thresholds and represents a shift from the seventh gear to the fifth gear. Arrow 408 does not cross any downshift threshold and so represents no shift from the eighth gear being proposed. Arrow 410 crosses one downshift threshold and represents a shift from the eighth gear to the seventh gear. Arrow 412 crosses one downshift threshold and represents a shift from the seventh gear to the sixth gear. Arrow 414 does not cross any downshift threshold and so represents no shift from the eighth gear being proposed. Arrow 416 crosses one downshift threshold and represents a shift from the eighth gear to the seventh gear.

[0138] Multiple downshifts can be expected to respond to any of the rapid increases in accelerator input represented by the arrows 402 to 416. However, if the magnitude of the increase is insufficient to cross multiple downshift thresholds, then only a multiple downshift will be made if the accelerator input continues to increase so as to cross a subsequent downshift threshold. This can result in a slower set of downshifts being made through a series of adjacent (in size) gear ratios, rather than a single direct downshift between non-adjacent gear ratios. This can give the impression of a lack of responsiveness to the accelerator input.

[0139] Figure 7A An example of the downshift thresholds of the second shift logic 500 is shown. The speed parameter ω is shown on the x-axis relative to the accelerator input a on the y-axis. In this example, the second shift logic 500 is applicable to the same range of accelerator inputs a as the first shift logic 400, but with a different speed parameter ω. The second shift logic 500 is applicable to a higher range of speed parameters ω than the first shift logic 400. Figure 6A and Figure 6BThe first shift logic 400 shown is the same as the eight-speed transmission. However, in the second shift logic 500, only five distinct downshift thresholds are visible. This is because two of the downshift thresholds are defined by a common function, and the other two are defined by another common function.

[0140] The rightmost line in this hierarchy represents both the downshift threshold for triggering a downshift from eighth to seventh gear and the downshift threshold for triggering a downshift from seventh to sixth gear, thus generating a valid downshift threshold for triggering a downshift from eighth to sixth gear. This valid downshift threshold is associated with skipping the seventh gear. Therefore, exceeding this valid downshift threshold can trigger a downshift from eighth to sixth gear, thus skipping the seventh gear.

[0141] The next line to the left represents both the downshift threshold used to trigger a downshift from sixth to fifth gear and the downshift threshold used to trigger a downshift from fifth to fourth gear, thus generating a valid downshift threshold for triggering a downshift from sixth to fourth gear. This valid downshift threshold is associated with skipping the fifth gear. Therefore, exceeding this valid downshift threshold can trigger a downshift from sixth to fourth gear, thus skipping the fifth gear.

[0142] The next line to the left indicates the downshift threshold used to trigger a downshift from fourth gear to third gear.

[0143] These downshift thresholds associated with downshifting from the eighth gear down to the third gear are defined by their respective functions, which are different from the corresponding downshift thresholds in the first shift logic 400.

[0144] The two leftmost lines represent downshifts to second and first gear, respectively. In some examples, they are defined by the same functions as the corresponding downshift thresholds defined in the first shift logic 400.

[0145] Multiple x-shaped markings 502 to 516 respectively represent the... Figure 6A The points in the parameter space described by the ends of arrows 402 to 416 are shown. Since the rate of increase of the accelerator input represented by arrows 402 to 416 exceeds the threshold rate, according to method 300, due to these increases, the effective shift logic changes from the first shift logic 400 to the second shift logic 500, and the target gear is based on the gear ratio associated with the region of the second shift logic 500 in which the described point is located.

[0146] In the second shift logic 500, the marker 502 is located within the region associated with the third gear. Thus, in response to the increase indicated by arrow 402, the proposed shift is from the fifth gear to the third gear. Thus, the method 300 achieves the benefit of an additional step in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 alone.

[0147] The marker 504 is located within the region associated with the third gear. Thus, in response to the increase indicated by arrow 404, the proposed shift is from the seventh gear to the third gear. Thus, the method 300 achieves the benefit of four additional steps in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 (and no shift proposed according to the first shift logic 400).

[0148] The marker 506 is located within the region associated with the fourth gear. Thus, in response to the increase indicated by arrow 406, the proposed shift is from the seventh gear to the fourth gear. Thus, the method 300 achieves the benefit of an additional step in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 alone.

[0149] The marker 508 is located within the region associated with the fourth gear. Thus, in response to the increase indicated by arrow 408, the proposed shift is from the eighth gear to the fourth gear. Thus, the method 300 achieves the benefit of four additional steps in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 (and no shift proposed according to the first shift logic 400).

[0150] The marker 510 is located within the region associated with the fourth gear. Thus, in response to the increase indicated by arrow 410, the proposed shift is from the eighth gear to the fourth gear. Thus, the method 300 achieves the benefit of three additional steps in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 alone.

[0151] The marker 512 is located within the region associated with the sixth gear. Thus, in response to the increase indicated by arrow 412, the proposed shift is from the seventh gear to the sixth gear. In this example, the method 300 does not achieve an immediate benefit in switching (block 340) as compared to the conventional control according to the first shift logic 400 alone, however, a benefit will result from continuing to control the automatic transmission 12 (block 350) according to the second shift logic 500.

[0152] The marker 514 is located within the region associated with the sixth gear. Thus, in response to the increase indicated by arrow 414, the proposed shift is from the eighth gear to the sixth gear. Thus, the method 300 achieves the benefit of two additional steps in the change in transmission ratio as compared to the conventional control according to the first shift logic 400 (and no shift proposed according to the first shift logic 400).

[0153] The marker 516 is within the region associated with the sixth gear. Thus, in response to the increase indicated by arrow 416, the suggested shift is from the eighth gear to the sixth gear. Thus, the method 300 achieves the benefit of an additional step in the change in transmission ratio compared to the conventional control according to the first shift logic 400 alone.

[0154] Thus, switching the active logic from the first shift logic 400 to the second shift logic 500 (block 340) can result in a suggested change in transmission ratio to a lower transmission ratio in one or more steps, despite not crossing any downshift threshold, or despite crossing fewer downshift thresholds than steps. It can be observed that this benefit is particularly great in terms of steps achieved when the starting value of the accelerator input is low, since in the first shift logic 400 the likelihood of crossing a downshift threshold without a change in speed (in response to but lagging the increasing accelerator input) is small except when the starting value of the accelerator input is already high.

[0155] In some examples, at least some of the downshift thresholds in the second shift logic 500 have a higher value of the speed parameter for a range of accelerator inputs than the corresponding downshift threshold in the first shift logic 400. This can be true for at least two of the downshift thresholds defined by the common function in the second shift logic 500. This can also be true for at least a further two of the downshift thresholds defined by the other common function in the second shift logic 500.

[0156] In at least two of the downshift thresholds defined by the common function, the one associated with triggering a downshift to the lowest transmission ratio (of the transmission ratios associated with the common function, not necessarily the absolute lowest transmission ratio available in the automatic transmission 12) has a higher value of the speed parameter for all accelerator inputs than the corresponding downshift threshold in the first shift logic 400. In Figure 7A In the example of FIG. 6, the one of the downshift thresholds associated with triggering a downshift to the lowest transmission ratio (of the transmission ratios associated with the common function) is the downshift threshold to the sixth gear.

[0157] In some examples, in at least two of the downshift thresholds defined by the common function, the one associated with triggering a downshift from the highest transmission ratio (of the transmission ratios associated with the common function) has a higher value of the speed parameter for all accelerator inputs than the corresponding downshift threshold in the first shift logic 400. In other examples (and as shown in the figures), the one of the downshift thresholds associated with triggering a downshift from the highest transmission ratio (of the transmission ratios associated with the common function) can have the same maximum value of the speed parameter for which a downshift can be triggered as the corresponding downshift threshold in the first shift logic 400. However, for all accelerator inputs in the first shift logic 400 whose corresponding downshift threshold is less than that maximum value, the speed parameter can have a higher value. Figure 7A In the example, the downshift threshold associated with triggering a downshift from the highest gear ratio (of the gear ratios associated with the common function) refers to the downshift threshold from the eighth gear.

[0158] Similarly, among at least two downshift thresholds defined by another common function, one downshift threshold associated with a downshift triggered to the lowest gear ratio (the gear ratio associated with the other common function, not necessarily the absolute lowest gear ratio available in the automatic transmission 12) can have a higher value for the speed parameter for all accelerator inputs compared to the corresponding downshift threshold in the first shift logic 400. Figure 7A In the example, a downshift threshold associated with triggering a downshift to the lowest gear ratio (in the gear ratio associated with another common function) refers to the downshift threshold to the fourth gear.

[0159] In some examples, among at least two downshift thresholds defined by another common function, one downshift threshold associated with triggering a downshift from the highest gear ratio (in the gear ratios associated with the common function) may have a higher value for the speed parameter for all accelerator inputs compared to the corresponding downshift threshold in the first shift logic 400. In other examples (and as shown in the figure), one downshift threshold associated with triggering a downshift from the highest gear ratio (in the gear ratios associated with the other common function) may have the same maximum value of the triggerable downshift speed parameter as the corresponding downshift threshold in the first shift logic 400. However, for all accelerator inputs in the first shift logic 400 whose corresponding downshift threshold is less than that maximum value, the speed parameter can have a higher value. Figure 7A In the example, a downshift threshold associated with triggering a downshift from the highest gear ratio (which is associated with another common function) refers to the downshift threshold from the sixth gear.

[0160] Therefore, during the control of the automatic transmission 12 according to the second shift logic 500 (box 350), the sixth and fourth gears can be engaged at higher values ​​of the speed parameters (compared to the control under the first shift logic 400). Their mechanical advantage of a higher gear ratio at the same speed relative to the control under the first shift logic 400 results in more responsive acceleration for the vehicle 1.

[0161] exist Figure 7A In the example, the downshift threshold from fourth gear to third gear also has the same maximum value of the triggerable downshift speed parameter as the corresponding downshift threshold in the first shift logic 400. ); however, it has a higher value of the speed parameter for all accelerator inputs for which the corresponding downshift threshold in the first shift logic 400 is less than this maximum value. In other examples, this downshift threshold in the second shift logic 500 can have a higher value of the speed parameter for all accelerator inputs compared to the corresponding downshift threshold in the first shift logic 400. In either case, the third gear can be engaged at a given speed with less accelerator input accordingly.

[0162] In some examples, at least some of the downshift thresholds in the second shift logic 500 do not change with accelerator input, or at least do not change with accelerator input below a maximum value of the accelerator input that can be reached without a forced downshift (not shown) in the event of an input from accelerator pedal depression. This can be true for at least two of the downshift thresholds in the second shift logic 500 that are defined by a common function. This can also be true for at least two other of the downshift thresholds in the second shift logic 500 that are defined by another common function. In Figure 7A In the example of FIG. 3, this is true for the two downshift thresholds representing a downshift from the eighth gear to the sixth gear, the two downshift thresholds representing a downshift from the sixth gear to the fourth gear, and the downshift threshold representing a downshift from the fourth gear to the third gear.

[0163] Thus, during control of the automatic transmission 12 according to the second shift logic 500 (block 350), a downshift from the eighth gear to the sixth gear will be triggered with the same value of the speed parameter (S1) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter. Thus, during control of the automatic transmission 12 according to the second shift logic 500 (block 350), a downshift from the eighth gear to the sixth gear will be triggered with the same value of the speed parameter (S1) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter.

[0164] Similarly, a downshift from the sixth gear to the fourth gear will be triggered with the same value of the speed parameter (S2) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter. Similarly, a downshift from the sixth gear to the fourth gear will be triggered with the same value of the speed parameter (S2) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter.

[0165] Further similarly, a downshift from the fourth gear to the third gear will be triggered with the same value of the speed parameter (S3) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter. Further similarly, a downshift from the fourth gear to the third gear will be triggered with the same value of the speed parameter (S3) regardless of the accelerator input. The triggering of this downshift is based entirely on the value of the speed parameter.

[0166] Thus, it can be observed that during the initial control of the automatic transmission 12 according to the first shift logic 400 (block 310), any increase in the accelerator input that is fast enough to trigger the mode switch (block 340) when the speed parameter value is between and will cause the sixth gear to be proposed as the target gear ratio. The sixth gear is the lowest gear ratio available for speeds in the range of to . Similarly, when the speed parameter value is between With When the vehicle speed is between and the lowest gear ratio applicable to vehicle speeds in the range

[0167] In the example of Figure 7A two of the downshift thresholds defined by the common function are associated with triggering a downshift from eighth gear to seventh gear, and triggering a downshift from seventh gear to sixth gear. These are chosen because in this example downshifts from eighth gear to sixth gear are downshifts that can be performed as direct shifts by the hardware of the automatic transmission 12. Likewise, in this example, downshifts from sixth gear to fourth gear are downshifts that can be performed as direct shifts by the hardware of the automatic transmission 12. In other examples, the hardware limitations of the automatic transmission 12 can be different, and different downshifts can be performed as direct shifts. Thus, it will be appreciated that for any given automatic transmission 12, at least two of the downshift thresholds defined by the common function can represent downshifts between two non-adjacent (in size) gear ratios that can be performed as direct shifts by the automatic transmission hardware. A direct shift differs from an interlocked or stepped shift in that none of the intermediate gear ratios are connected to the torque path to the wheels 34 during the shift from the current gear ratio to the target gear ratio.

[0168] Figure 7B An example of the upshift thresholds of the same second shift logic 500 is shown. The speed parameter ω is shown on the x-axis with respect to the accelerator input a on the y-axis. Seven upshift thresholds are shown. The leftmost of these lines represents the upshift threshold for triggering an upshift from first gear (the lowest gear ratio), and the rightmost of these lines represents the upshift threshold for triggering an upshift to eighth gear (the highest gear ratio). The lines in between represent in turn the upshift thresholds for triggering an upshift from second gear up to seventh gear.

[0169] At least some of the upshift thresholds do not change with accelerator input, or at least do not change with accelerator input below the maximum value of accelerator input that can be reached without a forced downshift (not shown) in the event of accelerator pedal depression. These upshift thresholds can be defined to trigger an upshift based entirely on the speed parameter value. The speed parameter values that trigger these upshifts are the maximum values that can trigger a corresponding upshift according to the first shift logic 400 (with forced downshifts in some examples, and without forced downshifts in some examples).

[0170] In this example, each of the upshift thresholds for triggering upshifts from the third gear up to the eighth gear does not vary with accelerator input. The upshift thresholds for triggering upshifts from the first and second gears are functions of accelerator input and are defined by the same functions as define the corresponding upshift thresholds in the first shift logic 400.

[0171] In the foregoing, it has been assumed that the first shift logic 400 is one of the set of first shift logics that has the highest dwell time during normal driving. That is, it is the one that is active most often during normal driving. Insofar as this is not the case, all aspects of the second shift logic 500 described or defined with respect to the first shift logic 400 can additionally or alternatively be understood as being described or defined with respect to the one of the set of first shift logics that has the highest dwell time during normal driving.

[0172] Figure 8 A further example of the method 300 is shown.

[0173] Blocks 310-350 are as described with respect to Figure 5 .

[0174] In this further example, if the rate of increase of accelerator input does not exceed the threshold rate (the "No" path from block 330), the method 300 proceeds to block 360. Block 360 includes determining whether the rate of increase of accelerator input exceeds a further, lower threshold rate.

[0175] If the rate of increase of accelerator input exceeds the further, lower threshold rate (the "Yes" path from block 360), the method 300 proceeds to block 370. Block 370 includes determining whether the downshift threshold of the first shift logic 400 (which is the currently active shift logic) is crossed.

[0176] If the downshift threshold of the first shift logic 400 is crossed (the "Yes" path from block 370), the method 300 proceeds to block 380. Block 380 includes switching from the first mode to the third mode of controlling the automatic transmission 12.

[0177] In some examples, the switching (block 380) depends on the downshift threshold of the first shift logic 400 being crossed while the rate of increase of accelerator input remains above the further, lower threshold rate, or the downshift threshold of the first shift logic 400 being crossed within a predefined period of time after the rate of increase of accelerator input is finally determined to exceed the further, lower threshold rate.

[0178] In the third mode, the automatic transmission 12 is controlled in accordance with a third shift logic 700, which is described with respect to Figure 10A and Figure 10BAn example of which is shown in FIG. 6. The third shift logic 700 is the shift logic that is active in the third mode.

[0179] Following the mode switch at block 380, block 390 therefore includes controlling the automatic transmission 12 in accordance with the third shift logic 700. The mode switch therefore includes changing the active shift logic. However, when operating in the third mode, the active shift logic is not changed. The automatic transmission 12 is controlled in accordance with the same third shift logic 700 until the third mode is exited. The third mode therefore does not involve using a different third shift logic that is calibrated to compensate for different road loads based on the current road load. Therefore, during operation in the third mode, the downshift threshold does not change with varying road loads.

[0180] If the rate of increase of accelerator input does not exceed a further lower threshold rate, or if the downshift threshold of the first shift logic 400 is not crossed, then the second mode is not entered. In some examples, operation continues in the first mode.

[0181] Figure 9 The same example of the downshift threshold of the first shift logic 400 is shown in FIG. 6. Figure 6A

[0182] A number of increases in accelerator input are shown for different starting values of accelerator input and for different values of the speed parameter at the time of increase. These are shown as vertical arrows 602 to 616 within the parameter space graph. The vertical arrows 602 to 616 each have the same length, representing the same magnitude of increase in a given time, in other words the same rate of increase. This rate of increase is less than the threshold rate with which the rate of increase of accelerator input is compared in block 330, but exceeds a further lower threshold rate with which the rate of increase of accelerator input is compared in block 360.

[0183] In the first shift logic 400, arrow 602 crosses the downshift threshold between the fifth gear and the fourth gear. Arrow 604 crosses the downshift threshold between the sixth gear and the fifth gear. Arrow 606 crosses the downshift threshold between the sixth gear and the fifth gear. Arrow 608 does not cross any downshift threshold and remains within the region associated with the eighth gear. Arrow 610 does not cross any downshift threshold and remains within the region associated with the sixth gear. Arrow 612 crosses the downshift threshold between the eighth gear and the seventh gear. Arrow 614 crosses the downshift threshold between the seventh gear and the sixth gear. Arrow 616 crosses the downshift threshold between the eighth gear and the seventh gear.

[0184] Figure 10A ​An example of the downshift threshold of the third shift logic 700 is shown. The speed parameter ω is shown on the x-axis with respect to the accelerator input a on the y-axis. In this example, the third shift logic 700 is for the same eight-speed transmission as the first shift logic 400 shown in FIG. 6 and Figure 9 The first shift logic 400 shown is for the same eight-speed transmission. However, in the third shift logic 700, only five distinct downshift thresholds can be seen. This is because two of the downshift thresholds are defined by one common function and another two of the downshift thresholds are defined by another common function.

[0185] The rightmost line of these lines represents both the downshift threshold for triggering a downshift from the eighth gear to the seventh gear and the downshift threshold for triggering a downshift from the seventh gear to the sixth gear, resulting in an effective downshift threshold for triggering a downshift from the eighth gear to the sixth gear. This effective downshift threshold is associated with a gear skip over the seventh gear. Thus, skipping over this effective downshift threshold can trigger a downshift from the eighth gear to the sixth gear, skipping the seventh gear.

[0186] In this example, the common function that defines the downshift threshold between the eighth gear and the seventh gear according to the third shift logic 700 and that defines the downshift threshold between the seventh gear and the sixth gear according to the third shift logic 700 is the same as the function that defines the downshift threshold between the eighth gear and the seventh gear according to the first shift logic 400.

[0187] The next line to the left represents both the downshift threshold for triggering a downshift from the sixth gear to the fifth gear and the downshift threshold for triggering a downshift from the fifth gear to the fourth gear, resulting in an effective downshift threshold for triggering a downshift from the sixth gear to the fourth gear. This effective downshift threshold is associated with a gear skip over the fifth gear. Thus, skipping over this effective downshift threshold can trigger a downshift from the sixth gear to the fourth gear, skipping the fifth gear.

[0188] In this example, another common function that defines the downshift threshold between the sixth gear and the fifth gear according to the third shift logic 700 and that defines the downshift threshold between the fifth gear and the fourth gear according to the third shift logic 700 is the same as the function that defines the downshift threshold between the eighth gear and the seventh gear according to the first shift logic 400 before the maximum value of the speed parameter at which a downshift between the sixth gear and the fifth gear can be triggered according to the first shift logic 400 is reached. This other common function, however, does not change with higher accelerator inputs.

[0189] Thus, the common function and the other common function are the same below a certain value of the accelerator input and then diverge above this certain value.

[0190] The next line to the left represents the downshift threshold for triggering a downshift from the fourth gear to the third gear.

[0191] In this example, the function defining the downshift threshold between the fourth gear and the third gear according to the third shift logic 700 is the same as the function defining the downshift threshold between the sixth gear and the fifth gear according to the first shift logic 400, before the maximum value of the speed parameter according to which a downshift between the fourth gear and the third gear can be triggered according to the first shift logic 400 is reached. The function defining the downshift threshold between the fourth gear and the third gear according to the third shift logic 700 does not change with higher accelerator inputs, then.

[0192] The two leftmost lines represent downshifts to the second gear and the first gear, respectively. In some examples, they are defined by the same functions as define the corresponding downshift thresholds in the first shift logic 400, respectively.

[0193] The several x-shaped markers 702 to 716 represent points within the parameter space described by the end of the arrows 602 to 616, respectively. Since the rate of increase of the accelerator input represented by the arrows 602 to 616 exceeds another, lower threshold rate, according to the method 300, the active shift logic can change from the first shift logic 400 to the third shift logic 700, if these increases also cause the downshift threshold in the first shift logic 400 to be crossed. If the active shift logic is changed to the third shift logic 700, the target gear is based on the gear ratio associated with the region of the third shift logic 700 in which the described point lies. Figure 9 Marker 702 lies within the region associated with the third gear in the third shift logic 700. Thus, in response to the increase represented by the arrow 602, the proposed shift is from the fifth gear to the third gear. Thus, the method 300 achieves the benefit of an additional step in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0194] Marker 704 lies within the region associated with the third gear. Thus, in response to the increase represented by the arrow 604, the proposed shift is from the sixth gear to the third gear. Thus, the method 300 achieves the benefit of two additional steps in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0195] Marker 706 lies within the region associated with the fourth gear. Thus, in response to the increase represented by the arrow 606, the proposed shift is from the sixth gear to the fourth gear. Thus, the method 300 achieves the benefit of an additional step in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0196] Marker 708 lies within the region associated with the fifth gear. Thus, in response to the increase represented by the arrow 608, the proposed shift is from the sixth gear to the fifth gear. Thus, the method 300 achieves the benefit of an additional step in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0197] The marker 708 is located within the region associated with the eighth gear. Thus, in response to the increase denoted by arrow 608, no shift is suggested. Since the increase denoted by arrow 608 does not cross any downshift threshold in the first shift logic 400, the active shift logic remains the first shift logic 400. It can be observed that the increase denoted by arrow 408 having a similar accelerator input starting value and speed parameter triggers a change in the active shift logic to the second shift logic 500, accompanied by four steps in the gear ratio change. This example highlights the advantage of the second shift logic 500 over the third shift logic 700.

[0198] The marker 710 is located within the region associated with the fourth gear in the third shift. However, since the increase denoted by arrow 610 does not cross any downshift threshold in the first shift logic 400, the active shift logic remains the first shift logic 400 and no shift from the sixth gear is suggested. This example highlights the advantage of the entry condition to the second mode over the entry condition to the third mode. If crossing the downshift threshold in the first shift logic 400 were not a condition for entry to the third mode (as it is not a condition for entry to the second mode), then the increase denoted by arrow 610 would achieve the benefit of an additional step in the gear ratio change compared to the regular control according to the first shift logic 400 alone. In fact, such a benefit is not achieved.

[0199] The marker 712 is located within the region associated with the fourth gear. Thus, in response to the increase denoted by arrow 612, the suggested shift is from the eighth gear to the fourth gear. Thus, the method 300 achieves the benefit of three additional steps in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0200] The marker 714 is located within the region associated with the sixth gear. Thus, in response to the increase denoted by arrow 614, the suggested shift is from the seventh gear to the sixth gear. In this case, the method 300 does not achieve the immediate benefit at the switch (block 380) compared to the regular control according to the first shift logic 400 alone, however, a benefit will arise from continuing to control the automatic transmission 12 (block 390) according to the third shift logic 700.

[0201] The marker 716 is located within the region associated with the sixth gear. Thus, in response to the increase denoted by arrow 616, the suggested shift is from the eighth gear to the sixth gear. Thus, the method 300 achieves the benefit of an additional step in the gear ratio change compared to the regular control according to the first shift logic 400 alone.

[0202] Thus, it can be observed that, while the method 300 achieves a significant benefit over continuing to operate in the first mode by providing a path into the third mode (block 360 to block 380) and operating in the third mode (block 390), the benefit is less than that achieved by providing a path into the second mode (block 330 to block 340) and operating in the second mode (block 350).

[0203] Figure 10B One example of upshift thresholds of the same third shift logic 700 is shown. The speed parameter ω is shown on the x-axis with respect to the accelerator input a on the y-axis. Seven upshift thresholds are shown. The leftmost line of these lines represents the upshift threshold for triggering an upshift from the first gear (lowest transmission ratio), and the rightmost line of these lines represents the upshift threshold for triggering an upshift to the eighth gear (highest transmission ratio). The lines in between represent, in turn, the upshift thresholds for triggering an upshift from the second gear up to the seventh gear.

[0204] In this example, each upshift threshold of the speed parameter from the first gear to the eighth gear changes with the accelerator input.

[0205] In this example, the upshift thresholds for triggering an upshift from the first and second gears are defined by the same function as the corresponding upshift thresholds in the first shift logic 400.

[0206] In this example, the upshift threshold for triggering an upshift from the seventh gear to the eighth gear is defined by the same function as the corresponding upshift threshold in the first shift logic 400.

[0207] In this example, each of the upshift thresholds for triggering an upshift from the third gear up to the seventh gear is the same as the upshift threshold for triggering an upshift from the seventh gear to the eighth gear until a respective maximum value of the speed parameter at which a corresponding upshift can be triggered according to the first shift logic 400 is reached. These upshift thresholds then do not change with higher accelerator inputs.

[0208] In general, each of the upshift thresholds in the third shift logic 700 can be unique. The third shift logic 700 can define a unique set of upshift points for each upshift. At least some of the upshift thresholds can coincide with each other for a range of accelerator inputs. For example, at low accelerator inputs, upshift points can be shared between at least two upshifts. At higher accelerator inputs, the upshift points associated with these at least two upshifts diverge.

[0209] In another example, the upshift thresholds of the third shift logic 700 are the same as those of the second shift logic 600 with respect to Figure 7BThe upshift threshold of the third shift logic 700 is similar to the upshift threshold of the second shift logic 500. That is, the upshift threshold of the third shift logic 700 is similar to the upshift threshold of the second shift logic 500. In examples where the upshift threshold of the third shift logic 700 is otherwise similar to the upshift threshold of the second shift logic 500, they can differ in that at least some of the upshift thresholds in the second shift logic 500 are set at higher values of the speed parameter compared to the corresponding upshift threshold in the third shift logic 700, for all or at least some accelerator inputs.

[0210] In the foregoing, it has been assumed that the first shift logic 400 is one of a set of first shift logics that has the highest residence time during normal driving. That is, it is the one of the first shift logics that is active most often during normal driving. In cases where this is not so, all aspects of the third shift logic 700 that have been described or defined with respect to the first shift logic 400 can additionally or alternatively be understood as being described or defined with respect to the one of the set of first shift logics that has the highest residence time during normal driving.

[0211] Figure 10A and Figure 10B The third shift logic 700 has been shown that can be used to control the automatic transmission 12 in the third mode entered at block 380 of the method 300. However, it will be appreciated that this third shift logic 700 can be used to control the automatic transmission 12 in the second mode entered at block 340 of the method 300, in place of Figure 7A and Figure 7B the second shift logic 600 shown.

[0212] Figure 11 An example of a method 800 for determining a threshold rate is shown, which is compared to the rate of increase of the accelerator input at block 330 of the method 300. The method 800 can be performed as a sub-method of the method 300 during block 310.

[0213] The method 800 comprises receiving as input parameters at least some of:

[0214] a current accelerator input, which is received at block 802;

[0215] a rolling average of the accelerator input, which is received at block 804;

[0216] a gear ratio currently proposed by the first shift logic 400, which is received at block 806;

[0217] a current road load, which is received at block 808; and

[0218] A current assessment of the driver's driving style is received at block 810.

[0219] These input parameters can be indicated by signals received by the control system 100, or can be output parameters from another method performed by the control system 100. As such, they can be received from an external source (relative to the control system 100) or have an internal source.

[0220] Block 814 comprises determining a first threshold value for the rate of increase of accelerator input.

[0221] In some examples, the first threshold value is determined based on the current accelerator input (received at block 802). The first threshold value can be determined from a lookup table stored in the memory 108 of the control system 100, the lookup table defining different threshold values for the rate of increase of accelerator input associated with different starting values of accelerator input. As such, the current accelerator input can be used as an index to the lookup table to extract the threshold value for the rate of increase of accelerator input starting from the current accelerator input. When the starting value of accelerator input is higher, the threshold value for the rate of increase of accelerator input will be lower. This can be particularly advantageous in the case where the accelerator input is derived from depression of an accelerator pedal, as if the driver has depressed the pedal, there is a limit to the speed of movement of the pedal, and hence a subsequent limit to the rate of increase of accelerator input. Conversely, when the driver is not depressing the pedal, they can accelerate their foot before starting to depress the pedal, enabling a higher rate of increase of accelerator input.

[0222] In other examples, the first threshold value is determined based on a difference between the current accelerator input (received at block 802) and a rolling average of accelerator input (received at block 804). The rolling average is an average of accelerator input over a rolling period having a fixed duration. The difference between the current accelerator input and the rolling average of accelerator input can be calculated by subtracting the rolling average of accelerator input from the current accelerator input; however, when the rolling average of accelerator input is greater than the current accelerator input, the difference will be set to zero. In these examples, the difference between the current accelerator input and the rolling average of accelerator input can be determined at block 812. Alternatively, the difference can be received as an input parameter to the method 800. In these examples, the first threshold value can still be determined from a lookup table stored in the memory 108 of the control system 100, however, the lookup table defines different threshold values for the rate of increase of accelerator input associated with different differences between the current accelerator input and the rolling average of accelerator input. As with the previous examples, when the starting value of accelerator input is higher, the threshold value for the rate of increase of accelerator input will be lower.

[0223] In some examples, the first threshold is also based on a current gear ratio suggested by the first shift logic 400 (received at block 806). The look-up table described above can be modified to include a second dimension in which different thresholds of rate of increase of accelerator input associated with different gear ratios are defined. The threshold of rate of increase of accelerator input can be higher when the gear ratio currently suggested by the first shift logic 400 is lower.

[0224] In some examples, the first threshold provides a threshold rate with which the rate of growth of accelerator input is compared at block 330 of the method 300. Accordingly, the threshold rate is provided as an output parameter of the method 800 at block 820. It will be appreciated that this output parameter forms an input parameter for another block in the method 300, specifically block 330, rather than an output from the control system 100.

[0225] In other examples, the first threshold represents a base threshold which can be further adjusted to take into account one or more of the driver's driving style and the road load. To this end, block 814 comprises determining an offset based on one or more of the driver's driving style and the road load, and then adding this offset to the first threshold (from block 812) at block 816 to provide the threshold rate with which the rate of increase of accelerator input is compared at block 330 of the method 300.

[0226] The offset can be determined (at block 814) in accordance with a further look-up table stored in the memory 108 of the control system 100, the further look-up table defining offsets associated with different assessments of the driver's driving style (in a first dimension) and offsets associated with different road loads (in a second dimension). The current road load (received at block 808) and the current assessment of the driver's driving style (received at block 810) can be used as indices to the further look-up table to extract the corresponding offset.

[0227] In some examples, the offset can be multiplied by a factor based on a current value of a speed parameter, which can be the same or different to the speed parameter which is an input parameter to the shift logic. For example, when the speed of the transmission output shaft 20 can be used as an input parameter to the shift logic, the multiplication factor applied to the offset can be based on the speed of the transmission input shaft 18.

[0228] The look-up tables used in the method 800 can be derived from experimental data, theoretical modelling, or a combination thereof.

[0229] An equivalent method using a look-up table with different calibration can be used to determine another lower threshold rate with which the rate of increase of accelerator input is compared at block 360 of the method 300.

[0230] Figure 12 An example of a method 900 of controlling the automatic transmission 12 of the vehicle 1 is shown. The method 900 can be performed by the control system 100 shown. Figure 3 In particular, the memory 108 can comprise computer readable instructions 110 which, when executed by the processor 106, perform the method 900.

[0231] The method 900 involves exiting from a mode in which the automatic transmission 12 is controlled in which the response time of the automatic transmission 12 to a rapid increase in accelerator input is improved. The method 900 involves switching back from the second mode to the first mode described above. In this example, the second mode from which the exit is made can correspond to the second mode or the third mode described above. The method of exiting from both of these modes is generally the same, but the threshold that must be exceeded can be different.

[0232] Block 910 comprises initial operation in the second mode. In this second mode, the automatic transmission 12 is controlled in accordance with the second shift logic 500 described above or the third shift logic 700 described above. The second (or third) shift logic 500, 700 is the shift logic that is active in this second mode.

[0233] As described above, the downshift threshold in the second (or third) shift logic 500, 700 does not change with varying road load.

[0234] Block 920 comprises receiving one or more signals indicative of the current road load.

[0235] As described above, the road load can be calculated from one or more of an estimated vehicle mass, an estimated gradient (road gradient), an estimated aerodynamic drag and an estimated rolling resistance, each of which can be indicated by signals received by the control system 100. Alternatively, the road load can be directly indicated by signals received by the control system 100. The road load calculated herein can include a difference between a road load for an empty vehicle travelling on a flat road and a road load that includes one or more of the above factors that can change during operation of the vehicle.

[0236] Block 930 comprises determining an exit threshold for the speed parameter based on the current road load. The exit threshold is a threshold that, when exceeded by the current value of the speed parameter, triggers an exit from the second mode.

[0237] In some examples, the exit threshold does not change with accelerator input, or at least does not change with accelerator input when the accelerator input is below a maximum value of accelerator input (achievable without input from the accelerator pedal triggering a mandatory downshift). In other examples, the exit threshold changes with accelerator input.

[0238] The exit threshold can be calibrated relative to the upshift threshold in the active shift logic 500, 700.

[0239] Thus, where the active shift logic is the second shift logic 500 described above, the exit threshold can not change with accelerator input, or at least not for accelerator inputs below a maximum value of accelerator input (achievable without triggering a kickdown (not shown) from the accelerator pedal), according to the upshift threshold relative to which the exit threshold is calibrated. Conversely, where the active shift logic is the third shift logic 700 described above, the exit threshold can change with accelerator input.

[0240] In some examples, the exit threshold is calibrated relative to the upshift threshold in the second (or third) shift logic 500, 700 associated with triggering an upshift to the highest gear ratio. The exit threshold can correspond to the upshift threshold in the second (or third) shift logic 500, 700 associated with triggering an upshift to the highest gear ratio when the current road load corresponds to driving on flat ground (0% gradient). When the current road load corresponds to driving uphill (>0% gradient), the exit threshold can comprise a higher value of the speed parameter than the upshift threshold in the second (or third) shift logic 500, 700 associated with triggering an upshift to the highest gear ratio, for all accelerator inputs, or for at least a range of accelerator inputs.

[0241] In other examples, a plurality of exit thresholds are calibrated relative to each of the upshift thresholds in the second (or third) shift logic 500, 700. The exit threshold used is then selected as the exit threshold calibrated relative to the upshift threshold in the second (or third) shift logic 500, 700 associated with triggering an upshift to the next higher gear ratio (relative to the current gear ratio). The exit threshold can correspond to the upshift threshold in the second shift logic 500 (or third shift logic 700) associated with triggering an upshift to the next higher gear ratio when the current road load corresponds to driving on flat ground. When the current road load corresponds to driving uphill, the exit threshold can comprise a higher value of the speed parameter than the upshift threshold in the second shift logic 500 (or third shift logic 700) associated with triggering an upshift to the next higher gear ratio, for all accelerator inputs, or for at least a range of accelerator inputs.

[0242] In some examples, the exit threshold is calibrated with respect to the first shift logic 400 that would be used at the current road load. For example, the exit threshold can be calibrated so that when exiting the second mode, the first mode is supported, the first shift logic 400 that would be used at the current road load would not recommend a shift or would only recommend a single step upshift.

[0243] Block 940 includes receiving a signal indicative of the current value of the speed parameter. In at least those examples involving an exit threshold that changes with accelerator input, block 940 also includes receiving a signal indicative of the current accelerator input.

[0244] Block 950 includes determining whether the current value of the speed parameter exceeds the exit threshold. If the exit threshold changes with accelerator input, block 950 includes determining whether the current value of the speed parameter exceeds the exit threshold at the current accelerator input.

[0245] In some examples, blocks 930-950 can be implemented using a lookup table of calibrated exit speeds. The lookup table includes particular values of road load that index a first dimension of the lookup table, and in some examples, particular values of accelerator input that index a second dimension of the lookup table. Thus, the current road load and in some examples the current accelerator input can be used to extract a corresponding exit speed. If an exit speed associated with an intermediate value of road load (or accelerator input) is needed, an interpolation between calibrated exit speeds can be used to estimate the exit speed. The calibrated exit speeds are larger when the road load is larger. This ensures that operation in the second mode lasts longer, which provides a more aggressive shift strategy while coping with larger road loads. The calibrated exit speeds can also be larger when the accelerator input is higher.

[0246] If the current value of the speed parameter exceeds the exit threshold (the “yes” path from block 950), the method 900 proceeds to block 960. Block 960 includes switching from operating in the second mode to operating in the first mode. Operation in the first mode is as described with respect to block 310 of the method 300.

[0247] If the current value of the speed parameter does not exceed the exit threshold (the “no” path from block 950), there is no exit from the second mode. However, the second mode can be exited (at block 340 or block 380) if the current value of the speed parameter does not exceed the exit threshold for a predefined period of time since starting operation in the second mode. The predefined period of time can be selected from several options based on which of the second shift logic 500 or the third shift logic 700 is active, and based on the longitudinal acceleration of the vehicle 1. The second mode can also be exited if the brakes of the vehicle are actuated.

[0248] To prevent a rapid switch back to the second mode after exiting the first mode, prerequisites for entering the second mode can be set. In some examples, this includes preventing a switch from the first mode to the second mode if the current value of the speed parameter is higher than an exit threshold associated with the current accelerator input. In some examples, hysteresis can be increased by requiring that the current value of the speed parameter is lower than an exit threshold associated with the current accelerator input. This variable can depend on the current road load and the current accelerator input.

[0249] As used herein, the term "obtain / obtaining" (and its grammatical variations) can include, but is not limited to: calculation, operation, processing, derivation, measurement, investigation, identification, searching (e.g., searching in a table, database, or other data structure), ascertaining, etc. Additionally, "obtain / obtaining" can include receiving (e.g., receiving information), accessing (e.g., accessing data in memory), determining, etc. Furthermore, "obtain / obtaining" can include solving, selecting, choosing, establishing, etc.

[0250] It should be understood that embodiments of the present invention can be implemented in any suitable form, in hardware, in software, or in a combination of hardware and software. For example, it is contemplated that the present invention is not limited to being implemented by a programmable processing device, and that at least some and all of the functions and / or method steps of the present invention in some embodiments can be equivalently implemented by non-programmable hardware, such as by a non-programmable ASIC, Boolean logic circuits, etc.

[0251] It will be understood that various changes and modifications can be made to the invention without departing from the scope of this application.

[0252] For the purposes of this disclosure, it should be understood that references to "the control system is configured as" should be construed as meaning "one or more controllers in the control system are configured together." The controllers described herein may each include a control unit or computing device having one or more electronic processors, which are configured together to perform the control system functions set forth in the control system claims.

[0253] Figures 5 to 12 The boxes shown may represent steps in a method and / or code segments in computer program 110. The illustration of a particular order of boxes does not necessarily imply a requirement or preferred order for the boxes, and the order and arrangement of the boxes may be changed. Furthermore, some steps may be omitted.

[0254] Features described in the preceding description can be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions can be performed by other features whether described or not. Although features have been described with reference to certain embodiments, those features can also be present in other embodiments.

Claims

1. A control system for an automatic transmission in a vehicle, the control system comprising one or more controllers, the control system being configured to: In the first mode, the automatic transmission is controlled according to a first shift logic, which defines a downshift threshold for a speed parameter as a function of the accelerator input, wherein... Each downshift threshold is defined by a unique function; In the second mode, the automatic transmission is controlled according to a second shift logic, which defines the downshift threshold of the speed parameter as a function of the accelerator input, wherein at least two downshift thresholds are defined by a common function; Receive a signal indicating the increasing rate of the accelerator input; and If the increase rate of the accelerator input exceeds the threshold rate, and regardless of whether the downshift threshold of the first shift logic is exceeded, the system switches from the first mode to the second mode.

2. The control system according to claim 1, wherein, The control system is configured to determine the threshold rate based on the current accelerator input.

3. The control system according to claim 1 or claim 2, wherein, The control system is configured to determine the threshold rate based on the difference between the current accelerator input and the rolling average of the accelerator input.

4. The control system according to any of the preceding claims, wherein, The control system is configured to determine the threshold rate based on the gear ratio currently suggested by the first shift logic.

5. The control system according to any of the preceding claims, wherein, The threshold rate is higher than another threshold rate, which is associated with leaving the first mode switching mode when a downshift threshold in the first shift logic is exceeded.

6. The control system according to any of the preceding claims, wherein, The at least two downshift thresholds defined by the common function represent a downshift between two non-adjacent gear ratios, which can be executed as a direct shift by the automatic transmission hardware.

7. The control system according to any of the preceding claims, wherein, At least two other downshift thresholds in the second shift logic are defined by another common function.

8. The control system according to any of the preceding claims, wherein, The at least two downshift thresholds defined by the common function in the second shift logic have higher values ​​for the speed parameters for a series of accelerator inputs compared to the corresponding downshift thresholds in the first shift logic.

9. The control system according to claim 8, wherein, At least some of the other downshift thresholds in the second shift logic have higher values ​​for the speed parameter than the corresponding downshift thresholds in the first shift logic for a series of accelerator inputs.

10. The control system according to any of the preceding claims, wherein, The at least two downshift thresholds defined by the common function do not change with the accelerator input.

11. The control system according to claim 10, wherein, At least some of the other downshift thresholds in the second shift logic do not change with accelerator input.

12. An automatic transmission system comprising an automatic transmission and a control system according to any of the preceding claims.

13. A vehicle comprising the automatic transmission system according to claim 12.

14. A method for controlling an automatic transmission of a vehicle, the method comprising: In the first mode, the automatic transmission is controlled according to a first shift logic, which defines downshift thresholds of speed parameters as functions of accelerator inputs, wherein each downshift threshold is defined by a unique function. In the second mode, the automatic transmission is controlled according to a second shift logic, which defines the downshift threshold of the speed parameter as a function of the accelerator input, wherein at least two downshift thresholds are defined by a common function; Receive a signal indicating the increasing rate of the accelerator input; and If the increase rate of the accelerator input exceeds the threshold rate, and regardless of whether the downshift threshold of the first shift logic is exceeded, the system switches from the first mode to the second mode.

15. A computer-readable instruction, which, when executed by a computer, is arranged to perform the method according to claim 14.

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