Patent Application
20060167565
The present invention generally relates to multi-state switching logic, and more particularly relates to robust methods, systems and devices for processing multi-state data.
Modern vehicles contain numerous electronic and electrical switches. Vehicle features such as climate controls, audio system controls other electrical systems and the like are now activated, deactivated and adjusted in response to electrical signals generated by various switches in response to driver/passenger inputs, sensor readings and the like. These electrical control signals are typically relayed from the switch to the controlled devices via copper wires or other electrical conductors. Presently, many control applications use a single wire to indicate two discrete states (e.g. ON/OFF, TRUE/FALSE, HIGH/LOW, etc.) using a high or low voltage transmitted on the wire.
To implement more than two states, additional control signals are typically used. In a conventional two/four wheel drive transfer control, for example, four active states of the control (e.g. 2WD mode, auto 4WD mode, 4WD LO mode and 4WD HI mode) as well as a default mode are represented using three to five discrete two-state switches coupled to a single or dual-axis control lever. As the lever is actuated, the various switches identify the position of the lever to place the vehicle in the desired mode. Power take-off (PTO) controls also typically contain three or more discrete switches to represent the various states of the PTO device, which is commonly used to power upfitter-installed accessories such as bucket lifts, snow plows, lift dump bodies and the like. Numerous other multi-state switches use multiple discrete switches to represent the various positions of a single or dual-axis control mechanism, which in turn represent the various states of a controlled device.
While many types of multi-state switches and switching systems have been applied in automotive and other settings, it is presently desirable to formulate multi-state switching devices that reduce the cost, complexity and weight associated with multiple input switches, wires and other components without sacrificing safety or robustness. Moreover, it is often desirable to diagnose certain signal conditions to identify shorts or other electrical issues within the switching system. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and the foregoing technical field and background.
Systems, methods and devices are described for robustly determining a desired operating state of a controlled device in response to the position of a multi-position actuator. In an exemplary embodiment, a robust control system for placing a controlled device into a desired one of a plurality of operating states in response to a position of a multi-position actuator suitably includes two or more sets of switch contacts each coupled to a reference signal and configured to switchably select between the reference signal and an intermediate value. Each set of switch contacts thereby provides an input values selected between the reference signal and the intermediate value in response to the position of the actuator. Control logic appropriately receives the input values and determines the desired operating state for the controlled device based at least in part upon the input values received. Robustness may be provided through proper selection of unique combinations of the input values used to represent the various operating states of the controlled device, as well as through mechanical interlocking and/or other techniques. Various control and switching systems may be formed from any number of contacts, including various configurations capable of representing two, four, eight or other numbers of operating states with one, two, three or more signal inputs.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:
The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description.
According to various exemplary embodiments, switching controls for use in vehicles and elsewhere may be formulated using ternary switching techniques. In contrast to conventional ternary switching, however, a single or common electrical reference may be used to limit the number of active signal values. Rather than providing the conventional three ternary signal values, for example, various embodiments are configured to provide only two of the three possible states. Because the switching circuitry is capable of detecting three signal values, yet only two values are actually used, the third value can be used as a diagnosable error value. That is, occurrences of the third value can be immediately identified as erroneous. Further, by selecting certain signal input combinations to represent the operating states of the controlled device and/or through mechanical interlocking of multiple switch contacts, the robustness of the system can be preserved, or even improved, over conventional binary signaling implementations. Switching systems as described herein may be used to implement robust selection schemes for various types of control mechanisms, including those used for Normal/Performance/Economy mode switching, cruise control switching, power take off (PTO) controls, “tap up/tap down” switching and/or the like.
Turning now to the drawing figures and with initial reference to
Switches 102A-B are any devices capable of providing various logic signals 106, 112A-B to components 104, 110 in response to user commands, sensor readings or other input stimuli. In an exemplary embodiment, switches 102A-B respond to displacement or activation of a lever 108A-B or other actuator as appropriate. Various switches 102A-B may be formulated with electrical, electronic and/or mechanical actuators to produce appropriate ternary output signals onto one or more wires or other electrical conductors joining switches 102 and components 104, 110, as described more fully below. These ternary signals may be processed by components 104, 110 to place the components into desired states as appropriate. In various embodiments, a single ternary signal 106 may be provided (e.g. between switch 102A and component 104 in
Many types of actuator or stick-based control devices provide several output signals 112A-B that can be processed to determine the state of a single actuator 108B. Lever 108B may correspond to the actuator in a 2WD/4WD selector, electronic mirror control, power take off selector or any other device operating within one or more degrees of freedom. In alternate embodiments, lever 108A-B moves in a ball-and-socket or other arrangement that allows multiple directions of movement. The concepts described herein may be readily adapted to operate with any type of mechanical selector, including any type of lever, stick, or other actuator that moves with respect to the vehicle via any slidable, rotatable or other coupling (e.g. hinge, slider, ball-and-socket, universal joint, etc.).
Referring now to
Switch contacts 212 are any devices, circuits or components capable of producing a binary, ternary or other appropriate output on conductor 106. In various embodiments, switch contacts 212 are implemented with a conventional double-throw switch as may be commonly found in many vehicles. Alternatively, contacts 212 are implemented with a multi-position operator or other voltage selector as appropriate. Contacts 212 may be implemented with a conventional low-current switch, for example, as are commonly found on many vehicles. Various of these switches optionally include a spring member (not shown) or other mechanism to bias an actuator 106 (
Switch contacts 212 generally provide an output signal selected from one or more reference voltages Vref and an “intermediate” or other value not directly associated with a reference signal. In an exemplary embodiment, Vref may be a high or low reference voltage such as ground, a battery voltage or the like. In various embodiments, the reference voltage is the same reference voltage provided to digital circuitry in vehicle 100 (
Contacts 212 are therefore operable to provide a signal 106 selected from a reference signal (e.g. Vref in the example of
The signals 106 produced by contacts 212 are received at a voltage divider circuit 216 or the like at component 104, 110 (
The voltages present at common node 208 are then provided to an analog-to-digital converter 202 to decode and process the signals 204 as appropriate. In various embodiments, A/D converter 202 is associated with a processor, controller, decoder, remote input/output box or the like. Alternatively, A/D converter 202 may be a comparator circuit, pipelined A/D circuit or other conversion circuit capable of providing digital representations 214 of the analog signals 204 received. In an exemplary embodiment, A/D converter 202 recognizes the high and low reference voltages, and assumes intermediate values relate to the intermediate state. In embodiments wherein B+ is equal to about five volts, for example, A/D converter may recognize voltages below about one volt as a “low” voltage, voltages above about four volts as a “high” voltage, and voltages between one and four volts as intermediate voltages. The particular tolerances and values processed by A/D converter 202 may vary in other embodiments.
As described above, then, signals 106 may be produced by contacts 212, transmitted across a single carrier, and decoded by A/D converter 202 in conjunction with voltage divider circuit 216. Intermediate signals that do not correspond to the traditional “high” or “low” outputs of contact 212 are scaled by voltage divider circuit 216 to produce a known intermediate voltage that can be sensed and processed by A/D converter 202 as appropriate. In this manner, conventional switch contacts 212 and electrical conduits may be used to transmit binary or ternary signals, thereby increasing the amount of information that can be transported over a single conductor. This concept may be exploited across a wide range of automotive and other applications.
Referring now to
In an exemplary embodiment, voltage divider 308 includes two or more resistors 302 and 304 electrically arranged between common node 208 and the input 306 to A/D converter 202. In
Using the concepts set forth above, a wide range of control circuits and control applications may be formulated, particularly within automotive and other vehicular settings. As mentioned above, the binary and/or ternary signals 106 produced by contacts 212 may be used to provide control data to any number of vehicle components 104, 110 (
With reference now to
Although
Each exemplary switch contact 212A-B in
In many embodiments, intermediate state 406 is most desirable for use as a “power off”, “default” or “no change” state of device 104, since the open circuit causes little or no current to flow from contacts 212, thereby conserving electrical power. Moreover, an ‘open circuit’ fault is typically more likely to occur than a faulty short to either reference voltage; the most likely fault (e.g. open circuit) conditions may therefore be used to represent the least disruptive states of device 104 to preserve robustness. Short circuit conditions, for example, may be used to represent an “OFF” state of device 104. In such systems, false shorts would result in turning device 104 off rather than improperly leaving device 104 in an “ON” state. On the other hand, some safety-related features (e.g. headlights) may be configured to remain active in the event of a fault, if appropriate. Accordingly, the various states of contacts 212 described herein may be re-assigned in any manner to represent the various inputs and/or operating states of component 104 as appropriate.
Various exemplary mappings of contacts 212 for certain automotive and other applications may be defined as appropriate. The concepts described above may be readily implemented to create a multi-state control that could be used, for example, to control a power takeoff, powertrain component, climate or audio system component, cruise control, other mechanical and/or electrical component, and/or any other automotive or other device. In such embodiments, two or more switch contacts 212 are generally arranged proximate to an actuator 108, with the outputs of the switches corresponding to the various states/positions of actuator 108. Alternatively, however, the various switch contacts 212 could interact with separate actuators 108, with the various input states representing the various positions of the distinct actuators. Stated another way, a common controller 402 may be used to decode the various states of multiple independent switch contacts 212A-B in any manner. Further, any number of binary, ternary and/or other types of switch contacts 212 may be interconnected or otherwise inter-mixed to create switching arrangements of any type.
The mappings and arrangements of input signals used to represent the states of device 104 may be assigned in any manner. In various embodiments, the outputs of the switches may be processed using conventional software logic, logic gates (e.g. AND/NAND, OR/NOR or the like) and/or processing circuitry to determine the state of the actuator. Signals 214A-B may be decoded by software instructions residing within memory 403 and executed by controller 402, for example. Alternatively, decoding logic may be formulated using any discrete, integrated or other components, or with any other combination of hardware and/or software.
In various embodiments, certain combinations of input signals may provide additional benefits such as reduced electrical current consumption, improved safety, or the like. Accordingly, by choosing the particular combinations of input signals used to represent the various operating states of device 104, control system 400 can be designed for improved performance, robustness and/or other factors. By associating the “default” state for device 104 with one or more “open circuit” positions of contacts 212, for example, the amount of current consumed when the device is in the default position may be reduced, since little or no current flows through the contact 212 when the contact is in the intermediate “open circuit” state. Because very little current flows while the switch is in this state, current consumption is minimized in the default state of device 104. Further, using the assumption that open circuits are more likely to be encountered than shorts to ground, which in turn are more likely than shorts to the battery voltage (B+), for example, the various device states can be mapped to the inputs such that least-desired state is associated with the input conditions that are least likely to occur accidentally.
Additional benefits may be realized by configuring the switch contacts 212 with a single electrical reference (Vref) such that the output is selected from the reference voltage and the intermediate value (e.g. open circuit). This single reference may correspond to a battery voltage, electrical ground or any other high or low reference value. Such embodiments allow occurrences of the unused signal value to be readily diagnosed at controller 402, thereby quickly identifying fault states or other undesirable conditions. That is, a switching system 400 that uses only “high” and “intermediate” values to represent operating modes of a controlled device can readily diagnose undesired occurrences of shorts to ground (which may appear as “low” values of signals 112A-B). Conversely, switching systems 400 that use only “low” and “intermediate” values can quickly diagnose undesired shorts to the battery voltage. Moreover, a single, common reference voltage may reduce the complexity of switching contacts 212 and/or system 400 as appropriate, and as described more fully below.
With particular reference now to
The various positions of actuator 108 are therefore indicated by the values of signals 112A and 112B. In the example shown in
Because the embodiment shown in
Robustness is further enhanced through the use of memory 403 or a similar structure to maintain past values of signals 214A-B for comparison with more contemporaneous values. By comparing prior values of signals 214A-B against current values, any illogical results can be readily identified and flagged or otherwise processed as appropriate. If the system 500 moves from a condition wherein Input1 is the reference voltage and Input2 is an open circuit, for example, to a condition wherein both inputs are open, it can be readily determined that a fault has occurred along Input1 (e.g. a signal line has broken, the reference voltage is no longer available, or the like). Such faults can therefore be isolated, flagged and/or processed as appropriate.
Timing restrictions may also be considered in various switching systems 500. Signal read/sample times, for example, should be configured to be longer than any debounce times associated with the switch contacts 212A-B to prevent erroneous readings. Moreover, in embodiments wherein security parameters are specified, it may be desirable to fix sample frequencies to allow one or more signal reads within the security window. In an exemplary embodiment wherein a 150 milli-second security parameter is specified and the switch contacts have a 10 milli-second debounce time, for example, signals may be read approximately every 20-50 milli-seconds or so to allow for two or more samples to be taken within the security time window. Sampling frequencies may be set within controller 402, or elsewhere as appropriate. Timing requirements may vary significantly from embodiment to embodiment, and may be variously on the order of microseconds or less to the order of seconds or greater. Other embodiments will not contain such stringent time constraints, however, and may not require timing configuration at all.
Similar concepts may be applied to embodiments having more than two operating states.
In the exemplary embodiment shown in
Similar concepts may be readily applied to switching systems using four or more inputs as well. In an exemplary four-input system, for example, up to eight unique states may be represented according to the following table:
As described above, the “Ref” value may refer to any high or low reference voltage, and the “v” may refer to any intermediate, open circuit or other value of the input signal. Accordingly, State 8 in Table 1 may be well-suited for use as a “default” mode in many embodiments to reduce current consumption. Table 1 can be a particularly beneficial embodiment when the “Ref” voltage is designed to be an electrical ground. Table 2 below represents a logical opposite of Table 1 above, with states in Table 2 representing fault states of the operating modes shown Table 1, and vice versa.
Many other arrangements of switches and signals could be formulated, with any signal or switch combinations used to represent any actuator position and/or operating mode of a controlled device in a wide array of alternate but equivalent embodiments.
The exemplary switching systems described with reference to
The concepts set forth herein may be applied in any number of practical settings, including various settings in automotive and other environments. By mapping the various operating positions of actuator 108 to the operating modes of a controlled device, numerous embodiments could be formulated across a wide array of commercial and other settings.
Control 800 could be used to implement any type of actuator-driven input device. Each of the various actuator positions 802, 804, 806 and 808 of control 800 could correspond to any “economy”, “performance” and/or “normal” operating modes of an engine or other vehicle component, for example. In such embodiments, the normal operating mode could correspond to “Default” position 802 to reduce the amount of current flow during normal operation. Similarly, the other non-default positions 804, 806 and 808 could be readily associated with other operating states of the controlled device. Alternate embodiments could use similar arrangement to implement audio or climate controls, for example, as well as engine controls or other vehicle controls. Similar concepts could be applied in audio or climate control systems, cruise control systems, power takeoff systems, engine throttle controls, transmission controls and/or any other control systems in automotive or other environments. Again, the concepts described herein could be applied across a wide array of equivalent applications.
The general concepts described herein could be modified in many different ways to implement a diverse array of equivalent multi-state switches, actuators and other controls. The various positions of actuator 108 may be extracted and decoded through any type of processing logic, including any combination of discrete components, integrated circuitry and/or software, for example. Moreover, the various positional and switching structures shown in the figures and tables contained herein may be modified and/or supplemented in any manner. Still further, the concepts presented herein may be applied to any number of ternary and/or discrete switches, or any combination of ternary and discrete switches to create any number of potential or actual robust and non-robust state representations. Similar concepts to those described above could be applied to four or more input signals, for example, allowing for control systems capable of processing any number of robust states in a wide array of equivalent embodiments.
Although the various embodiments are most frequently described with respect to automotive applications, the invention is not so limited. Indeed, the concepts, circuits and structures described herein could be readily applied in any commercial, home, industrial, consumer electronics or other setting. Ternary switches and concepts could be used to implement a conventional joystick, for example, or any other pointing/directing device based upon four or more directions. The concepts described herein could similarly be readily applied in aeronautical, aerospace, marine or other vehicular settings as well as in the automotive context.
While at least one exemplary embodiment has been presented in the foregoing detailed description, a vast number of variations exist. The various circuits described herein may be modified through conventional electrical and electronic principles, for example, or may be logically altered in any number of equivalent embodiments without departing from the concepts described herein. The exemplary embodiments described herein are intended only as examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing one or more exemplary embodiments. Various changes can therefore be made in the functions and arrangements of elements set forth herein without departing from the scope of the invention as set forth in the appended claims and the legal equivalents thereof.
