US-12617290-B2 - Dynamic vehicle speed control

US12617290B2US 12617290 B2US12617290 B2US 12617290B2US-12617290-B2

Abstract

A system for controlling a vehicle speed of a vehicle is described. The system comprises a motor, a vehicle speed sensor, a vehicle speed governor, and a controller. The motor is configured to provide an output torque for driving the vehicle. The vehicle speed sensor provides a vehicle speed signal corresponding to the vehicle speed. The vehicle speed governor has a vehicle speed limit for the vehicle, where the vehicle speed governor adjusts the vehicle speed limit according to a desired direction of travel of the vehicle and a load corresponding to the motor. The desired direction of travel is selectable by an operator of the vehicle. The controller is configured to adjust the output torque of the motor according to the vehicle speed limit and the vehicle speed signal.

Inventors

Balan Mariappan Selvaraj
Gajendran Bakthavachalam
Oluwademilade Adedunmolu Alabi
Richard A. Booth
Jaime Antonio Lugo-Castillo

Assignees

CUMMINS INC.

Dates

Publication Date: 20260505
Application Date: 20230530

Claims (20)

1 . A system for controlling a vehicle speed of a vehicle, the system comprising: a motor configured to provide an output torque for driving the vehicle; a vehicle speed sensor that provides a vehicle speed signal corresponding to the vehicle speed; a vehicle speed governor having a vehicle speed limit for the vehicle, wherein the vehicle speed governor adjusts the vehicle speed limit according to a desired direction of travel of the vehicle and a load corresponding to the motor, the desired direction of travel being selectable by an operator of the vehicle; and a controller configured to adjust the output torque of the motor according to the vehicle speed limit and the vehicle speed signal, wherein the controller is configured to receive the vehicle speed signal as a primary feedback input and to modulate the output torque of the motor to maintain a target vehicle speed, the modulation being performed independent of terrain grade, vehicle configuration parameters, and operator inputs, and wherein the vehicle speed governor selects from a set of predefined vehicle speed limits based on a selected direction of travel and applies a speed droop function that reduces the selected speed limit in proportion to motor load, wherein the speed droop function is selected based on a brake mechanism status.
2 . The system of claim 1 , wherein: the vehicle speed limit is a first vehicle speed limit for a reverse direction of travel for the vehicle; the vehicle speed governor has a second vehicle speed limit for a non-reverse direction of travel for the vehicle; and the first vehicle speed limit is lower than the second vehicle speed limit, wherein: the first vehicle speed limit is selected when a reverse gear of the vehicle is selected; the second vehicle speed limit for the non-reverse direction is selected when a first forward gear of the vehicle is selected; the vehicle speed governor has a third vehicle speed limit for the non-reverse direction of travel; the third vehicle speed limit is selected when a second forward gear of the vehicle is selected; and the third vehicle speed limit is higher than the second vehicle speed limit.
3 . The system of claim 1 , wherein the vehicle speed governor dynamically reduces the vehicle speed limit in response to an increase in the load corresponding to the motor and the controller adjusts the output torque of the motor according to the reduced vehicle speed limit and the vehicle speed signal, and wherein the vehicle speed governor reduces the vehicle speed limit using the load as an input to a speed droop function that provides a proportional reduction to the vehicle speed limit.
4 . The system of claim 3 , the system further comprising: a brake mechanism configured to receive an indication of a desired change in the vehicle speed; wherein the speed droop function is a first speed droop function that provides a first proportional reduction, the vehicle speed governor having a second speed droop function that provides a second proportional reduction; and wherein the vehicle speed governor uses the first speed droop function responsive to the brake mechanism being in a released state and uses the second speed droop function responsive to the brake mechanism being in an applied state.
5 . The system of claim 4 , wherein the first proportional reduction is lower than the second proportional reduction.
6 . The system of claim 4 , wherein: the first speed droop function is configured to be operable over a first range of the load; and the second speed droop function is configured to be operable over a second range of the load that is smaller than the first range.
7 . The system of claim 4 , wherein the first proportional reduction is less than the second proportional reduction for a given load of the motor.
8 . The system of claim 1 , wherein the vehicle comprises a direct-drive electric vehicle or a hybrid vehicle and the motor is operably coupled to a battery and a charge system, the modulation being performed independent of the terrain grade, the vehicle configuration parameters including gear ratio and tire size, and the operator inputs including accelerator pedal position.
9 . A system for controlling a vehicle speed of a vehicle, the system comprising: a motor configured to provide an output torque for driving the vehicle; a vehicle speed sensor that provides a vehicle speed signal corresponding to the vehicle speed of the vehicle; a brake mechanism configured to receive an indication of a desired change in the vehicle speed; a vehicle speed governor having a vehicle speed limit for the vehicle, wherein the vehicle speed governor adjusts the vehicle speed limit according to a first speed droop function responsive to the brake mechanism being in a released state and according to a second speed droop function responsive to the brake mechanism being in an applied state; and a controller configured to adjust the output torque of the motor according to the vehicle speed limit and the vehicle speed signal, wherein the vehicle speed governor is configured to select from a plurality of predefined speed droop functions based on a detected drive mode and brake application state, and to apply the selected speed droop function to dynamically reduce the vehicle speed limit in response to increased motor load, such that the vehicle speed limit in reverse mode is lower than in forward mode, and transitions between modes are applied without recalibration of control parameters, and wherein the plurality of predefined speed droop functions includes at least one droop function for a reverse drive mode that applies a lower target speed limit, and a second droop function for a forward drive mode that applies a higher target speed limit, each responsive to brake status, and wherein transitions between the droop functions are applied dynamically without requiring calibration adjustments.
10 . The system of claim 9 , wherein: the vehicle speed governor dynamically reduces the vehicle speed limit in response to an increase in a load corresponding to the motor; and the controller adjusts the output torque of the motor according to the reduced vehicle speed limit and the vehicle speed signal.
11 . The system of claim 10 , wherein the first speed droop function provides a first proportional reduction and the second speed droop function a second proportional reduction.
12 . The system of claim 11 , wherein the first proportional reduction is lower than the second proportional reduction.
13 . A method for controlling a vehicle speed of a vehicle, the method comprising: receiving an application status of a brake mechanism for the vehicle; selecting a first speed droop function responsive to the brake mechanism being in a released state and a second speed droop function responsive to the brake mechanism being in an applied state; adjusting a vehicle speed limit according to the selected speed droop function; adjusting an output torque of a motor for driving the vehicle according to the vehicle speed limit and a vehicle speed signal corresponding to the vehicle speed of the vehicle; and selecting the vehicle speed limit based on a direction of travel and applying a direction-specific droop function that reduces the selected speed limit in proportion to motor load and a status of the brake mechanism, wherein a controller is configured to prevent successive adjustments to the vehicle speed limit in response to transient changes in motor load by applying a delay before modifying the vehicle speed limit, such that the output torque of the motor remains stable unless a sustained change in load is detected.
14 . The method of claim 13 , wherein adjusting the vehicle speed limit comprises reducing the vehicle speed limit as a load of the motor increases according to the selected speed droop function.
15 . The method of claim 14 , wherein: the first speed droop function provides a first proportional reduction and the second speed droop function a second proportional reduction; and the first proportional reduction is lower than the second proportional reduction.
16 . The method of claim 15 , wherein the first proportional reduction is less than the second proportional reduction for a given load of the motor.
17 . The system of claim 1 , wherein the vehicle speed governor is further configured to select the speed limit from among a plurality of limits based on a gear selection and a direction of travel.
18 . The system of claim 1 , wherein the speed droop function is dynamically switched based on a brake status signal without recalibration of torque-speed mappings.
19 . The system of claim 9 , wherein the controller is configured to disable application of a selected speed droop function during a predefined limp-home mode or service state to enable continued operation of the vehicle with reduced performance while preventing undesirable modulation of the vehicle speed limit under at least one of fault conditions and service conditions.
20 . The method of claim 13 , further comprising determining the application status of the brake mechanism from at least one of a hydraulic pressure sensor and an electronic brake control unit, wherein the brake status is used to select or modify a speed droop function applied by the controller to dynamically govern the vehicle speed limit.

Description

BACKGROUND Vehicles may be operated over a wide range of speeds, for example, high speeds on a highway, slow speeds when maneuvering to park or position the vehicle, etc. Management of vehicle speed may be assisted by a vehicle speed governor that uses a pre-set vehicle speed limit. For example, a maximum speed governor may use a pre-set vehicle speed limit of 65 miles per hour for a tractor trailer or a cruise control governor may use an adjustable speed limit selectable by an operator. In some examples, an idle speed governor may use a pre-set idle speed (e.g., 1500 revolutions per minute) that is matched to a vehicle speed for “creeping” a vehicle at low vehicle speeds. Generally, a torque converter allows a vehicle equipped with an Automatic Transmission (AT) to seamlessly edge forward (or backward) from a full stop with little or no effort from the operator, up to a vehicle speed corresponding to the idle speed. A direct-drive electric vehicle is powered by the engagement of a motor and a battery without the need of an engine or transmission. The motor receives power from the energy stored in the direct-drive vehicle battery. In general, direct-drive electric vehicles are an efficient alternative to a vehicle with an internal combustion engine (ICE) that utilizes gasoline or diesel power. Unlike the ICE, a direct-drive electric vehicle does not have a combined driveline clutch and minimum power plant speed that establishes a minimum vehicle speed. However, operating a direct-drive electric vehicle at very low speeds and loads may be inefficient. In a parking or other low speed maneuvering situation, it may be desirable to have precise control over an output torque of the motor. Moreover, direct-drive electric vehicles may have different configurations of transmission gear ratios, rear axle ratios, or tire size that make calibration of a vehicle speed (e.g., miles per hour) relative to a motor speed (e.g., revolutions per minute) challenging. It is with respect to these and other general considerations that embodiments have been described. Also, although relatively specific problems have been discussed, it should be understood that the embodiments should not be limited to solving the specific problems identified in the background. SUMMARY A system for controlling a vehicle speed of a vehicle is provided. The system comprises a motor configured to provide an output torque for driving the vehicle; a vehicle speed sensor that provides a vehicle speed signal corresponding to the vehicle speed; a vehicle speed governor having a vehicle speed limit for the vehicle; and a controller configured to adjust the output torque of the motor according to the vehicle speed limit and the vehicle speed signal. The vehicle speed governor adjusts the vehicle speed limit according to a desired direction of travel of the vehicle and a load corresponding to the motor, the desired direction of travel being selectable by an operator of the vehicle. A system for controlling a vehicle speed of a vehicle is provided. The system comprises: a motor configured to provide an output torque for driving the vehicle; a vehicle speed sensor that provides a vehicle speed signal corresponding to the vehicle speed of the vehicle; a brake mechanism configured to receive an indication of a desired change in the vehicle speed; a vehicle speed governor having a vehicle speed limit for the vehicle; and a controller configured to adjust the output torque of the motor according to the vehicle speed limit and the vehicle speed signal. The vehicle speed governor adjusts the vehicle speed limit according to a first speed droop function responsive to the brake mechanism being in a released state and according to a second speed droop function responsive to the brake mechanism being in an applied state. A method for controlling a vehicle speed of a vehicle is provided. The method comprises: receiving an application status of a brake mechanism for the vehicle; selecting a first speed droop function responsive to the brake mechanism being in a released state and a second speed droop function responsive to the brake mechanism being in an applied state; adjusting a vehicle speed limit according to the selected speed droop function; and adjusting an output torque of a motor for driving the vehicle according to the vehicle speed limit and a vehicle speed signal corresponding to a vehicle speed of the vehicle. This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter. BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES Non-limiting and non-exhaustive examples are described with reference to the following Figures. FIG. 1 shows a schematic block diagram of an example vehicle having a brake mechanism and co