Abstract:
A control system for vehicle accessories differentiated from one another in terms of required voltage, current drawn, load duration and variability of energization levels utilizes generic interface modules to effect control. One or more generic remote interface modules, in addition to controllers such as engine and chassis controllers, are mounted on the vehicle for controlling actuation and energization of the non-standard devices, such as motors driving pumps for hydraulic lits. An electronic system controller (ESC) manages the remote interface modules over a serial communication link to provide the specialized functionality. Each remote interface module (RIM) is constructed as a standard component capable of providing digital and analog outputs to devices attached to one or more output ports on the module. The remote interface assumes a number of controller states under the control of the electronic system controller for regulating actuation and energization of the differentiated loads. Input ports are also provided for digital and analog inputs from sensors, which signals may be formatted for transmission to the electronic system controller. The electronic system controller includes memory for storing a data structure specifying permissible remote interface module states and a map to the module&#39;s ports to provide for the actuation and energization of the differentiated loads.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention: 
     The present invention relates to a system for multiplexed communications on vehicles and particularly relates to providing non-specialized remote interface modules from which may be invoked specialized functionality by an electronic system controller. The remote interface modules operate specific vehicle systems under the direction of an electronic system controller communicating with the remote interface module over a multiplexed communication system. The electronic system controller is programmable to implement, in sequence, certain states on the remote interface module(s). The present invention further relates to a method for installing the programming on electronic system controllers. 
     2. Description of the Prior Art: 
     Multiplexed communications involve data transmission interconnections which interleave nonsynchronous digital signals into a single serial signal. Multiplexed communication systems also provide the reverse function (demultiplexing) of dividing the single signal into multiple, nonsynchronous digital signals. Applied to motor vehicles, multiplexed serial communication paths are seen as an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, device and gauges installed on the vehicles. With each increase in the number and variety of accessories and functions installed on each vehicle, the benefits of using a single, multiplexed serial communication link for passing instructions to and receiving information from vehicle devices as diverse as running lights and rear axle temperature sensors becomes greater. Multiplexing the signals to and from vehicle systems promises greater physical simplicity through displacing much of the vehicle wiring harness, the reduction of manufacturing costs, the enabling of vehicle electrical load management, and the enhancement of system reliability. The development by the Society of Automotive Engineers of the J1939 series of standards for multiplexed communications testifies to the progress in the application of multiplexed communications to vehicles. Standards have been or are being developed relating the communication path, transmission collision detection, diagnostic ports and data protocols, among other topics. 
     A multiplexed serial communications system can link several remote digital controllers positioned around a vehicle with an electrical system controller (ESC) for two way communication. Remote digital controllers are addressable, allowing them to respond to signals intended for them initialize particular functions. They may also include programming that allows the device to react to local conditions as well as condition indicating signals provided the controller. The ESC may pass requests and instructions received for operations of certain devices, addressed to the correct remote controller, in a fashion to condition the timing and duration of the responses to requests to better manage overall vehicle electrical load. 
     U.S. Pat. No. 4,809,177 to Windle, et al., which is assigned to the assignee of this patent, relates to a multiplexed communications system in which a central controller organizes signals to various vocational controllers distributed about a vehicle. The distributed controllers included internal data processing capability and programming. Among the controllers were engine, cab and chassis controllers. The environment of Windle et al. is a limited multiplexing environment, where much operational responsibility is distributed to the controllers. 
     Windle et al. teach a controller constructed according to a single design suitable for use both as a chassis controller and a cab controller. The chassis controller handles the engine brakes, the ignition, the air conditioning compressor and some external lights while the cab controller handled other external lights, the air conditioning compressor, the windshield wiper motor, among other functions. The dual purpose controller is a microprocessor based system running stored programs in local memory. The controller is adapted to handle one or the other of the differing sets of functions by being reprogrammed and by applying different inputs to the device. Reprogramming involved overwriting non-volatile memory or replacing programmable read only memory units. Windle et al. recognized that if a controller could be constructed in accordance with a single design for different vocations, benefits would be gained in terms of inventory costs and manufacturing costs, and anticipated improvements in reliability. However, Windle et al. did not attempt to extend the idea of single design controller outside of an environment where the requirements on the controller could be fully anticipated nor did they attempt to remove specialized programming from the distributed controllers. 
     The extension of the idea of applying a generic controller to differing vocations is greatly complicated where the chassis manufacturer may not know the functions to which a controller will be put. Remote controllers are more readily applied to vehicles where the accessories to be installed on the vehicle are fairly standardized, even if numerous, than they are to commercial vehicles where the vehicle&#39;s required vocations are less predictable. This is especially true where a manufacturer provides a chassis and the purchaser adds extensive functionality. A number of examples of this situation come readily to mind, for example, coach builders of luxury busses, fire trucks and ambulances all place highly specialized requirements on a vehicle&#39;s electrical system which may, or may not, be known to the chassis manufacturer. In some cases these requirements may even be unique to a particular vehicle. Still, it is desirable for a coach builder to be able to adapt a serial communication system for the functionality of its bodies and to be able to specify accessory functionality without the need to hardwire that functionality into the vehicle. 
     Substantial economies of scale could be gained from using a standardized component for several vocations on commercial vehicles. The ability to support such a device would also simplify assembly and allow for smaller parts inventories, as partially achieved by Windle et al. Were remote controllers truly multi-application ready, greater differentiation in vehicles would also be obtainable. 
     SUMMARY OF THE INVENTION 
     According to the invention there is provided a vehicle having a plurality of electrical loads, differentiated from one another in terms of required voltage, current drawn, load duration and variability of energization levels. One or more generic remote interface modules, in addition to controllers such as engine and chassis controllers, are mounted on the vehicle for controlling actuation and energization of the non-standard devices, such as motors driving pumps for hydraulic lifts. An electronic system controller (ESC) manages the remote interface modules over a serial communication link to provide the specialized functionality. Each remote interface module (RIM) is constructed as a standard component capable of providing digital and analog outputs to devices attached to one or more output ports on the module. The remote interface assumes a number of controller states under the control of the electronic system controller for regulating actuation and energization of the differentiated loads. Input ports are also provided for digital and analog inputs from sensors, which signals may be formatted for transmission to the electronic system controller. The electronic system controller includes memory for storing a data structure specifying permissible remote interface module states and a map to the module&#39;s ports to provide for the actuation and energization of the differentiated loads. 
     The communication system is accessible over a diagnostic port which may be externally accessed to write a database which specifies RIM functionality to ESC memory. During manufacture, vehicle specific databases for remote interface modules are tagged to chassis vehicle identification numbers (VINs). During chassis assembly, the diagnostic port is accessed and the VINs are retrieved from the ESC by an off-vehicle manufacturing support computer to which the database for the vehicle&#39;s remote interface module has been previously stored. The database is then downloaded to the vehicle to provide specialized response characteristics for the remote interface module. 
     Additional effects, features and advantages will be apparent in the written description that follows. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself however, as well as a preferred mode of use, further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawings, wherein: 
     FIG. 1 is a perspective view of a vehicle electrical system; 
     FIG. 2 is a schematic of the vehicle electrical control system contained within the vehicle electrical system of FIG. 1; 
     FIG. 3 is a functional illustration of an electrical system controller; and 
     FIG. 4 is an illustration of a database providing the functional specification for a remote interface module connected to the vehicle electrical system. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a perspective view of a vehicle electrical system  10  installed on a vehicle  13 . Vehicle electrical system  10  comprises an electronic system controller (ESC)  30 , which is the primary component of a vehicle electronic control system. ESC  30  manages a number of vocational controllers disposed on vehicle  13  and executes a load management program which oversees the total load imposed on the vehicle electrical system and power train by various accessories installed on the vehicle. Most active vehicle components are directly controlled by the vocational controllers, which include a gauge cluster  14 , an engine controller  20 , a transmission controller  16 , an auxiliary instrument and switch bank  12 , an antilock brake system (ABS) controller  102 , and one or more remote interface modules  40 . All vehicle electrical components are attached to a harness  18 , which includes a serial data link, power and ground conductors. The serial data link is a twisted pair cable constructed in accordance with SAE standard J1939 and is externally accessible via a diagnostic port  36 . 
     Gauge cluster  14 , transmission controller  16 , ABS controller  102  and engine controller  20  may be implemented to exercise substantial local control, incorporating their own local microprocessors and programming and coupled by input and output ports to sensors and controllable elements in the areas under their respective control. For example, engine controller  20  may monitor an exhaust gas sensor (not shown) on one input channel for indications of unburned fuel in the exhaust and modify control signal(s) effecting the fuel/air mixture. The signals controlled may move a control valve or change the operation of a fuel pump and their determination may take into account the demands for engine power. Similarly, ABS controller  102  can engage brakes per an externally applied command, but modify the actuation signal to the brakes upon sensing skidding. 
     The loads imposed on vehicle  13  systems controlled by the electronic control system of the present invention are usually electrical loads, however, a remote interface module  40  (or a controller such as transmission controller  16 ) may electronically control the engagement of mechanical devices to the power train of vehicle  13 . Gear selection in an automatic transmission would be just one example. Other nonelectrical loads could include the control of a clutch for an air conditioning compressor and actuation of pumps driven by the vehicle drive train. 
     Gauge cluster  14 , transmission controller  16  and engine controller  20  all communicate with electronic system controller  30 , which also monitors inputs received from the auxiliary instrument and switch bank  12 , over the serial communication link in harness  18 . Electronic system controller  30  may be programmed to override the normal response characteristics of the gauge cluster  14 , transmission controller  16  and engine controller  20 , should electrical and mechanical loads exceed the capacity of the vehicle, should requests conflict with one another, and under other circumstances. 
     A remote interface module  40  also communicates with ESC  30 . Remote interface module  40  is a general purpose control interface allowing the attachment of various accessories to vehicle  13 . As described below, remote interface module  40  provides a plurality of ports providing for each of the following: analog inputs; analog outputs; digital inputs; and digital outputs. Characterization of a particular port as, for example, an output port, does not necessarily mean that it functions exclusively as an output port. For example, an output port may include voltage drop sensing elements, current flow sensing elements, or both, allowing determination by ESC  30  of whether, for example, a bulb in a lamp connected to the output port is operative, or whether a short circuit condition exists in an attached device. 
     FIG. 2 is a schematic illustration of an electronic control system  70  implemented within vehicle electrical system  10 . Electronic control system  70  includes a microprocessor  72  based electronic system controller (ESC)  30 . ESC  30  coordinates multiplexed transmissions of signals on serial communication link  42  and executes a load management program as part of a process a comprehensive control of one or remote interface modules (RIMs)  40 A and B. ESC  30  comprises a microprocessor  72  executing programs stored in memory  74 . Memory  74  is constructed in conventional manner and includes volatile and non-volatile sections, the latter of which is preferably fabricated from flash technology electrically erasable programmable read only memory (EEPROM). A network interface  73  implements J1939 communications over serial communication link  42 . 
     Serial communication link  42  interconnects the auxiliary instrument and switch bank  12 , the gauge cluster  14 , the transmission controller  16 , engine controller  20 , ABS controller  102 , and RIMs  40 A and  40 B. Additionally, instrument and switch bank  12  may be connected to cab controller  16  by a private data link  44 . All system components are powered by a vehicle electrical power system  45 . 
     While the gauge cluster  14 , transmission controller  16  and engine controller  20  have well defined tasks, RIMs  40 A and  40 B have no predetermined vocation and have no distinguishing attribute vis-a-vis one another other than their respective addresses and possibly the number of ports supported. RIMs  40 A and  40 B may nonetheless be applied to the control of various highly differentiated accessories. 
     RIM  40 A may be taken as representative of both RIMs. While represented by discreet functional boxes, much of RIM  40 A except the J1939 transceiver  50  is conventionally realized using a microcontroller  71 . Microcontroller  71  can, under the direction of appropriate inputs mimic various circuit and logic elements, such as oscillators, buffers, analog to digital converters, feed back loops, et cetera. RIM  40 A always includes a J1939 transceiver element  50  and a controller area network module  52  which handle communications tasks defined by the J1939 standard over serial communication link  42 . RIM  40 A typically controls, and in some cases drives, both analog and digital devices. RIM  40 A also accepts inputs from both digital and analog devices, primarily switches and sensors. A plurality of ports  54 A through  54 F are provided allowing connection to several digital and electrical devices. While six ports are shown, RIM  40 A allows some salability and the number of ports may be greater or fewer than six. 
     To explain the operation of RIM  40 A a set of functional elements are illustrated, though it will be understood by those skilled in the art that the depicted elements are representative only. All functional elements are invoked by ESC  30  through signals communicated to RIM  40 A over serial communication link  42 . The attachment of analog devices (not shown) is accommodated by interposing digital to analog (D/A) converters  56  and analog to digital (A/D) converters  58  between a microprocessor  60  and ports  56 A-F. D/A converter  56  allows digital outputs from the microcontroller to be scaled to an analog signal level. A/D converter  58  will typically accept an analog signal from a sensor. Some analog devices may be driven from applying pulse width modulation to a digital output port. 
     Output control circuitry  60 , and thereby RIM  40 A, can assume any of several states and sequences of states in response to signals received from ESC  30  in order to apply the appropriate output signals on ports  56 A-C. Output circuitry  60  may functionally comprise buffers and gating circuitry allowing: scaled signals to be applied to the D/A converters  56 ; and pulse width modulated or digital signals to be supplied directly to output ports  54 A and  54 B. An oscillator may be mimicked by repeated alternation of a series of states on an output port. Particular arrangements of buffers, gating circuitry and the like is organized by channels A, B and C, each of which may be individually addressed by ESC  30  through channel address recognition circuitry  63 . 
     Inputs may be received on one or more of input ports  54 D to  54 F and from there transferred to input serializing circuitry  62 . Inputs, such as voltage drop or current drawn, may also be taken from any one of output ports  54 A- 54 C. Input signals may be associated with a particular input channels by serializing the signals using the clock input from clock  65 , which is used to control sampling of the signals received from ports  54 D and  54 E and to control sampling by AID converter  58 . 
     ESC  30  determines output states for RIM  40 A based, among other things, on the values for signals received on input ports  54 D to  54 F, inputs from the instrument and switch bank  12 , previous states of the RIM, and load management considerations, which in turn may be influenced by inputs received the engine controller  20 , the chassis controller  16  and cab controller  14 . ESC  30  is essentially a computer based on a microprocessor  72  executing stored programs on data stored in memory  74  and communicating with the previously described controllers and remote interface modules through a network adaptor  73  using the J1939 standard and permissible extensions thereto. The data structures defining the functionality of RIMs  40 A and  40 B are written to memory  74  during vehicle assembly via diagnostic port  36  from an external assembly computer  46  using a database  82 . The particular data structure written will be developed for the vehicle from its engineering specifications. 
     Data is communicated in both directions between ESC  30  and RIMs  40 A and  40 B using the J1939 protocol, which provides in turn for certain proprietary protocols and extensions within the standard. To implement the present invention it necessary to extend the protocol to allow the identification of ports within RIMs. 
     FIG. 3 illustrates the operation of ESC  30 . Among the central functions of ESC  30  are the execution of a load management program  95  and execution of a signals processing program  93  which handles management of data traffic on the serial communication link in accordance with the SAE J1939 protocols and permissible extensions thereto. Load management program  95  is a real time interpreter running in an endless loop that scans a set of values or states stored in state buffering section  94  of the signals processing program  93 . A possible timing cycle of the loop is 10 milliseconds. All ESC  30  actions are conditioned upon the receipt and periodic update of signals received, such as operator inputs, received primarily from the chassis controller  16  and the cab controller  14 , engine controller  20  signals and signals from the RIM(s), which may streamed to allow association with the inputs with particular ports, or may be received in response to an interrogation, in which case addressing information may be returned with the response. 
     All input and output signals are coordinated by a signals processing program  93 , which can poll RIMs, assign port values to RIM signals, in reference database  96  and which also stores values obtained in a state buffering table  94  for the use of the load management program  95 . 
     RIM database  96  characterizes the output for each output port of all RIMs for selected circumstances. For example, a RIM may be installed on a vehicle intended for use as a fire fighting pumper. The pump may be driven by an electric motor powered by the vehicle or it may be driven from a clutch allowing connection to the vehicle drive shaft. The conditions or circumstances controlling actuation of a pump coupled to a RIM may de developed as follows: (1) has pump operation been requested (on/off operator input on a digital RIM input port, determined by periodic request for input port status); (2) is the pump currently on or off; (3) vehicle battery voltage; and (4) what are pump R.P.M.&#39;s or the current drawn by the pump&#39;s prime mover. In this example, vehicle battery voltage is monitored to determine if the vehicle is producing enough power to support all of the demands being made on it. A drop in battery voltage below a minimum threshold may entail a response. Pump R.P.M.&#39;s may be monitored to make sure that the pump is loaded, i.e. that it is connected to a water source and/or not cavitating. Where the pump is driven by an electric motor a similar determination may be indicated by looking at the voltage drop across its power inputs (which may in the RIM, or a across a switch operated by the RIM). A small voltage drop may indicate that the pump is not moving any water. ESC  30  directs actuation of outputs which can include a signal to the RIM to turn on the pump, for example by engaging a clutch, which signal will indicate the appropriate RIM address and port address, and may extend to a request to the engine to increase idle speed. The pump may be turned off if inputs indicate the pump is engaged but not loaded. 
     An excellent example of how RIM functionality depends directly on ESC  30  operation is provided by the way in which oscillating output signals are generated from RIM  40 . This is done by the ESC  30  issuing alternating on and off signals at the appropriate frequency to reproduce an oscillating output. All output states, and sequences of output states of a RIM  40 , are under the control of the ESC  30 , which determines these states by execution of the load management program with reference to RIM database  96 . The mapping of outputs to the appropriate port(s) is also supplied by database  96 . While the digital controller  71  of a RIM is programmed and capable of reproducing a number of types of functionality, invocation of specific functions lies entirely with ESC  30 . 
     The load management program  95  executes is tasks, in so far as relate to RIMs, by reference to a RIM database  96  as illustrated in FIG.  4 . RIM functions may be expressed in a number of different ways, such as truth tables  80 , state machines  81 , boolean expressions  82  and transfer functions  83 . Each such element will include a port mapping  84 . The port mappings  84  define both entry points to truth tables, boolean expressions and the like for inputs received from a RIM as well as output values. 
     While the invention is shown in only one of its forms, it is not thus limited but is susceptible to various changes and modifications without departing from the spirit and scope of the invention.