Method and system for providing a headway function to an adaptive speed control activation switch

Abstract: This invention relates to a method and system for providing a headway function to an activation switch for an adaptive speed control system for a vehicle. The method includes determining whether the adaptive speed control activation switch has been actuated, and, if the adaptive speed control activation switch has been actuated, determining whether the adaptive speed control system is active. The method also includes, if the adaptive speed control system is active, controlling a headway function of the adaptive speed control system in response to the actuation of the adaptive speed control activation switch. The system includes a receiver capable of receiving an input signal indicative of the actuation of the adaptive speed control activation switch, and a controller capable of determining whether the adaptive speed control system is active if the adaptive speed control activation switch has been actuated. The controller is also capable of controlling a headway function of the adaptive speed control system in response to the actuation of the adaptive speed control activation switch if the adaptive speed control system is active.

Description: Technical Field This invention relates to a method and system for providing a headway function to an activation switch for an adaptive speed control system for a vehicle. Background Art Adaptive Cruise ( i.e. , speed) Control (ACC) systems operate much like conventional Cruise Control systems, with the added capability of being able to sense in-path vehicles and to slow the ACC equipped vehicle in response. An ACC equipped vehicle thereby allows its operator to automatically control the vehicle speed, as with conventional Cruise Control, without the necessity of having to deactivate and reactivate control whenever slower traffic is encountered. As is well known in the art, existing ACC methods and systems use a forward-looking range sensor such as radar to sense an in-path vehicle (which may also be referred to as a sensed target or primary target). Based on the radar sensor information, such ACC methods and systems then determine the range and relative velocity (or range rate) of the sensed in-path vehicle. Using the range and range rate, the speed of the ACC equipped vehicle is controlled to maintain a selected following interval between the ACC equipped vehicle and the sensed in-path vehicle. The following interval, also referred to a headway, is set at a default value upon activation of such ACC methods and systems, and is modifiable by the vehicle operator within a predefined range of values. The speed of the ACC equipped vehicle is typically controlled by automatic control of the vehicle throttle actuator. In more advanced ACC methods and systems, vehicle speed may also be controlled by automatic control of vehicle brake actuators. Such ACC methods and systems have the ability to apply a moderate degree of braking to the vehicle to achieve further vehicle deceleration ( i.e. , in addition to vehicle deceleration achieved via throttle control) in response to an in-path vehicle. Thus, existing ACC methods and systems must provide the vehicle operator with not only the ability to activate the vehicle ACC system, but to select a following interval as well. To do so, however, existing ACC methods and systems employ two vehicle operator switches, one for activating the ACC system and another for adjusting a headway setting. Moreover, in a vehicle equipped with a standard speed control systems, when an ACC system is added to the vehicle, an additional vehicle operator switch must be provided for adjusting a headway setting. An example of such an ACC system having multiple operator switches is described in EP 0 876 936 Al, in which the ACC system may initially be activated by move a control lever up or down. Following activation of the ACC system, the desired following interval may be selected using a button on the dashboard. As a result, there exists a need, in an ACC system for a vehicle, for a method and system for providing a headway function to the ACC system activation switch. Such a method and system would determine whether the adaptive speed control activation switch has been actuated, and, if so, determine whether the adaptive speed control system is already active. If the adaptive speed control system is active, such a method and system would then control a headway function of the adaptive speed control system in response to the actuation of the adaptive speed control activation switch. Such control would include adjusting the headway setting of the adaptive speed control system. By providing an adaptive speed control activation switch with such dual capability, such a method and system would eliminate the need for two separate vehicle operator switches, thereby reducing cost. Disclosure of the Invention Accordingly, it is a principal object of the present invention to provide, in an adaptive speed control system, a method and system for providing a headway function to an adaptive speed control activation switch. According to the invention there is provided a method for controlling the speed of an adaptive cruise control (ACC) equipped vehicle depending on a following interval between the ACC equipped vehicle and an in-path vehicle, the ACC equipped vehicle having an ACC system with an ACC activation switch, a controller and a display for displaying the following interval, the method comprising the steps of: i) using the controller to determine if the ACC activation switch has been actuated; ii) following step i), if it has been determined that the ACC activation switch has been actuated, then using the controller to determine if the ACC system has already been activated; iii) if in step ii) it has been determined that the ACC system has not already been activated by a previous actuation of the same ACC activation switch, then using the controller to activate the ACC system to control the following interval between the ACC equipped vehicle and an in-path vehicle; characterised in that if in step ii) it has been determined that the ACC system has already been activated by a previous actuation of the same ACC activation switch, the method comprises the steps of using the controller to determine whether a following interval setting is displayed by the display, and if a following interval setting is not displayed, then displaying a following interval setting on the display for a selected time period. The invention also provides an adaptive cruise control (ACC) system for controlling a following interval between an ACC equipped vehicle and an in-path vehicle, the ACC system comprising an ACC activation switch, a controller and a display for displaying the following interval, wherein: a) the controller is arranged to determine if the ACC activation switch has been actuated; b) and if the controller determines that the ACC activation switch has been actuated, then the controller is arranged to determine if the ACC system has already been activated; c) and if following determination by the controller that the ACC system has not already been activated by a previous actuation of the same ACC activation switch, then the controller is arranged to activate the ACC system to control the following interval between the ACC equipped vehicle and an in-path vehicle; characterised in that if following determination by the controller that the ACC system has already been activated by a previous actuation of the same ACC activation switch, then the controller is arranged to determine whether a following interval setting is displayed by the display, and if a following interval setting is not displayed, then the controller is arranged to display a following interval setting on the display for a selected time period. An adaptive speed control system for a vehicle is also disclosed, for providing a headway function to an adaptive speed control activation switch. The system comprises a receiver capable of receiving a signal indicative of actuation of the adaptive speed control activation switch, and a controller capable of determining whether the adaptive speed control system is active if the adaptive speed control activation switch has been actuated. The controller of the system of the present invention is also capable of controlling a headway function of the adaptive speed control system in response to the actuation of the adaptive speed control activation switch if the adaptive speed control system is active. These and other objects, features and advantages of the present invention will be readily apparent upon consideration of the following detailed description of the invention in conjunction with the accompanying drawings. Brief Description of the Drawings The invention will now be further described, by way of example with reference to the accompanying drawings, in which: Figure 1 is a simplified block diagram of an adaptive cruise control system, including the system of the present invention; and Figure 2 is a flowchart including the method of the present invention. Detailed Description Referring to Figures 1 and 2, the preferred embodiment of the method and system of the present invention will now be described. In that regard, Figure 1 illustrates a simplified block diagram of an Adaptive Cruise Control (ACC) system, including the system of the present invention, denoted generally by reference numeral 10. In general, as is well known to those of ordinary skill in the art, ACC system 10 is a closed loop control system intended to respond to potential targets in front of and in the same lane of traffic as the vehicle equipped with the ACC system 10. The goal of ACC system 10 is to partially automate the continuous longitudinal control of the vehicle, thereby providing the vehicle operator with improved comfort and convenience. In that regard, ACC system 10 may operate in either a normal or a following mode. In normal mode operation, ACC system 10 controls the speed of the ACC equipped vehicle to the speed set by the vehicle operator as the control speed. In following mode operation, ACC system 10 controls the speed of the ACC equipped vehicle to the speed of a sensed in-path vehicle (which may be referred to as a sensed target or a primary target). More specifically, as seen in Figure 1, the ACC system 10 includes a vehicle controller 12 provided in communication with a range sensor 14, a speed sensor 16, a yaw rate sensor 18, a user interface 20, a throttle actuator 22, and a brake actuator 24. As previously described, the system 10 extends the function of conventional speed control systems. In that regard, based on range and relative velocity information obtained and/or derived from forward looking range sensor 14 and speed sensor 16, vehicle controller 12 uses throttle and brake actuators 22,24 to control the speed of the ACC equipped vehicle in order to maintain a selected following interval (in seconds) between the ACC equipped vehicle and a sensed target ( i.e. , a lead vehicle) in the forward path of travel of the ACC equipped vehicle. The following interval between the ACC equipped vehicle and the sensed target is initially set at a default value (typically two seconds) upon activation of the system 10, but may be modified by the vehicle operator to a number of other selectable values (typically a value greater than or equal to one second, but less than or equal to two seconds) via user interface 20. The default following interval is typically the maximum following interval allowed, and modification of the following interval by the vehicle operator is permitted between that maximum and a defined minimum following interval (typically one second). The following interval is referred to as headway, and is defined as the range to the sensed target (in meters), divided by the speed of the ACC equipped vehicle (in meters per second). User interface 20 is also used by the vehicle operator to set the desired vehicle control speed. In that regard, user interface 20 includes a switch (not shown) which may be actuated by the vehicle operator to activate the ACC system 10 ( i.e. , an "on/off" switch), as well as a switch (not shown) which may be actuated by the vehicle operator to adjust a headway setting. User interface 20 also includes an indicator (not shown) for indicating to the vehicle operator whether the ACC system 10 is active and, if so, the currently selected headway setting. The indicator is typically visual, and generally takes the form of a lamp and/or an LED in the vehicle instrument panel for displaying the information described above to the vehicle operator, although any number of other types of indicators are possible. As previously noted, ACC systems and methods are well known in the art. As a result, a detailed description of the general operation of ACC system 10, including such functions as acquisition, discrimination, differentiation, selection and tracking of targets, range and relative velocity (range rate) determinations, sensor operations, and throttle and brake control is unnecessary and, for the sake of brevity, is not set forth herein. In connection with the method and system of the present invention, such functions of ACC system 10 may be undertaken in any fashion known to those of ordinary skill. As also previously noted, existing ACC methods and systems must provide the vehicle operator with not only the ability to activate the vehicle ACC system, but to select a headway setting as well. To do so, however, existing ACC methods and systems employ two vehicle operator switches, one for activating the ACC system and another for adjusting the headway setting. Moreover, in a vehicle equipped with a standard speed control systems, when an ACC system is added to the vehicle, an additional vehicle operator switch must be provided for adjusting the headway setting. In contrast to the prior art, the present invention provides, in the ACC system 10 of Figure 1, a method and system for providing a headway function to the existing ACC system activation switch. Such a method and system determine whether the adaptive speed control activation switch has been actuated, and, if so, determine whether the adaptive speed control system is already active. If the adaptive speed control system is active, such a method and system then control a headway function of the adaptive speed control system in response to the prior actuation of the adaptive speed control activation switch. Such control includes adjusting the headway setting of the adaptive speed control system. By providing an adaptive speed control activation switch with such dual capability, the method and system of the present invention eliminate the need for two separate vehicle operator switches (one for ACC activation and another for adjusting the ACC headway setting), thereby reducing cost. Referring again to Figure 1, the system of the present invention is preferably included in vehicle controller 12. In that regard, vehicle controller 12 includes a receiver (not shown) capable of receiving an input signal indicative of the actuation of the activation switch of the adaptive speed control system. Vehicle controller 12 also includes a controller (not shown) capable of determining whether the adaptive speed control system is active if the adaptive speed control activation switch has been actuated. If the adaptive speed control system is not active, the controller is capable of generating a control signal operative to activate the adaptive speed control system. Alternatively, if the adaptive speed control system is active, the controller of the system of the present invention is capable of controlling a headway function of the adaptive speed control system in response to the actuation of the activation switch. It should be noted here that the controller (as well as vehicle controller 12 of ACC system 10) may take the form of an appropriately programmed microprocessor, or any equivalent thereof. To control a headway function in response to the actuation of the activation switch, the controller is capable of determining whether a headway setting is displayed to the vehicle operator via user interface 20 of the adaptive speed control system. If such a headway setting is not displayed, the controller is capable of generating a control signal operative to display a headway setting to the vehicle operator for a selected time period via user interface 20. To control a headway function in response to actuation of the activation switch, the controller is also capable of determining whether a headway setting equals a predetermined minimum value (typically one second as described above). If the headway setting equals the predetermined minimum value, the controller is capable of setting the headway setting equal to a predetermined maximum value (typically two seconds as described above). If the headway setting does not equal the predetermined minimum value, the controller is capable of setting the headway setting to one of a plurality of predetermined values less than the predetermined maximum value ( i.e., setting the headway setting to one of a number of values less than two seconds). In either case, the controller is further capable of generating a control signal operative to display the headway setting to the vehicle operator via user interface 20. Referring now to Figure 2, a flowchart of the method of the present invention is shown, denoted generally by reference numeral 40. As seen therein, according to the method 40 of the present invention, a check 42 of the ACC system switches is undertaken, and it is determined 44 whether the adaptive speed control activation ( i.e. , "on/off") switch has been pressed. If not, the check 42 of the ACC system switches is again undertaken. Alternatively, if the adaptive speed control activation switch has been actuated, according to the method of the present invention, it is determined 46 whether the adaptive speed control system is already active. If not, the adaptive speed control system is activated 48, and the headway is set 50 at the default maximum predetermined value (typically two seconds). Subsequently, the check 42 of the ACC system switches is again undertaken. However, if the adaptive speed control system is already active, it is then determined 52 whether a headway setting is being displayed to the vehicle operator by the adaptive speed control system. If not, the currently selected headway setting ( i.e. , the default maximum predetermined value) is displayed 54 for a selected time period (i.e., "x" seconds) to the vehicle operator. Thereafter, the check 42 of the ACC system switches is undertaken again. Alternatively, however, if a headway setting is being displayed to the vehicle operator, it is then determined 56 whether the currently selected headway setting equals a predetermined minimum value (typically one second). If not, the currently selected headway setting is set equal to one of a plurality of predetermined values less than the predetermined maximum value ( i . e ., one of a number of values less than two seconds). Preferably, the currently selected heating setting is set equal to the next lower value 58. Thereafter, the newly selected headway setting is displayed 54 to the vehicle operator for a selected time period, and the check 42 of the ACC system switches is undertaken again. If, however, the currently selected headway setting equals the predetermined minimum value, then the currently selected headway setting is set equal to a predetermined maximum value 60, and the check 42 of the ACC system switches is again undertaken. In such a fashion, with respect to the setting of the headway value, the headway is initially set at the default maximum value. Thereafter, each actuation of the adaptive speed control activation switch toggles the headway setting to the next available lower value, ultimately down to the predetermined minimum value. At that point, the next actuation of the adaptive speed control activation switch toggles the headway setting back to the maximum value, and the process repeats. Each headway setting selected is also displayed to the vehicle operator. From the foregoing description, it can be seen that the present invention provides, in an ACC system, a method and system for providing a headway function to the existing ACC system activation switch. The method and system determine whether the adaptive speed control activation switch has been actuated, and, if so, determine whether the adaptive speed control system is already active. If the adaptive speed control system is active, the method and system then control a headway function of the adaptive speed control system in response to the prior actuation of the adaptive speed control activation switch. Such control includes adjusting the headway setting of the adaptive speed control system. By providing an adaptive speed control activation switch with such dual capability, the method and system of the present invention eliminate the need for two separate vehicle operator switches (one for ACC activation and another for adjusting the ACC headway setting), thereby reducing cost. While various embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the scope of the invention.

Claims: A method for controlling the speed of an adaptive cruise control (ACC) equipped vehicle depending on a following interval between the ACC equipped vehicle and an in-path vehicle, the ACC equipped vehicle having an ACC system (10) with an ACC activation switch, a controller (12) and a display for displaying the following interval, the method comprising the steps of: i) using (42,44) the controller (12) to determine if the ACC activation switch has been actuated; ii) following step i), if it has been determined that the ACC activation switch has been actuated, then using (46) the controller (12) to determine if the ACC system (10) has already been activated; iii) if in step ii) it has been determined that the ACC system (10) has not already been activated by a previous actuation of the same ACC activation switch, then using (48) the controller (12) to activate the ACC system (10) to control the following interval between the ACC equipped vehicle and an in-path vehicle; characterised in that if in step ii) it has been determined that the ACC system (10) has already been activated by a previous actuation of the same ACC activation switch, the method comprises the steps of using the controller (12) to determine whether a following interval setting is displayed by the display, and if a following interval setting is not displayed, then displaying a following interval setting on the display for a selected time period. A method as claimed in Claim 1, wherein in step iii), the ACC system (10) controls the following interval between the ACC equipped vehicle and an in-path vehicle at a maximum following interval. A method as claimed in Claim 1 or Claim 2, wherein the method comprises if it has been determined in step ii) that the ACC system (10) has already been activated by a previous actuation of the same ACC activation switch, the step of using the controller (12) to determine whether a following interval setting is displayed by the display, and if a following interval setting is displayed, then using the controller (12) to determine whether the following interval setting equals a predetermined minimum value and if the following interval setting equals the predetermined minimum value, then using the controller (12) to set the following interval setting to be a predetermined maximum value. A method as claimed in Claim 3, wherein following the setting of the following interval setting to said predetermined maximum value, the method comprises the step of displaying said following interval setting on the display for a selected time period. A method as claimed in any preceding claim, wherein the method comprises if it has been determined in step ii) that the ACC system (10) has already been activated by a previous actuation of the same ACC activation switch, the step of using the controller (12) to determine whether a following interval setting is displayed by the display, and if a following interval setting is displayed, then using the controller (12) to determine whether the following interval setting equals a predetermined minimum value and if the following interval setting is not equal to the predetermined minimum value, then using the controller (12) to set the following interval setting to be one of a plurality of predetermined values less than said following interval. A method as claimed in Claim 5, wherein following the setting of the following interval setting to said one of a plurality of predetermined values, the method comprises the step of displaying said following interval setting on the display for a selected time period. An adaptive cruise control (ACC) system (10) for controlling a following interval between an ACC equipped vehicle and an in-path vehicle, the ACC system comprising an ACC activation switch, a controller (12) and a display for displaying the following interval, wherein: a) the controller (12) is arranged to determine if the ACC activation switch has been actuated; b) and if the controller (12) determines that the ACC activation switch has been actuated, then the controller (12) is arranged to determine if the ACC system (10) has already been activated; c) and if following determination by the controller (12) that the ACC system (10) has not already been activated by a previous actuation of the same ACC activation switch, then the controller (12) is arranged to activate the ACC system (10) to control the following interval between the ACC equipped vehicle and an in-path vehicle; characterised in that if following determination by the controller (12) that the ACC system (10) has already been activated by a previous actuation of the same ACC activation switch, then the controller (12) is arranged to determine whether a following interval setting is displayed by the display, and if a following interval setting is not displayed, then the controller (12) is arranged to display a following interval setting on the display for a selected time period.

Inventors: FRIEDRICH MARK PETER, RAHAIM SAM G, SIELAGOSKI GERALD L, FRIEDRICH, MARK PETER, RAHAIM, SAM G., SIELAGOSKI, GERALD L.
Applicants: VISTEON GLOBAL TECH INC, VISTEON GLOBAL TECHNOLOGIES, INC.
Application year: 2000
Main classification: B60K31
IPC codes: B60K31