Abstract:
A control system for a vehicle provides for the control of electrically differentiated loads utilizing a local controller, the functionality of which depends upon a programmed central control unit. A first serial data link connects a plurality of autonomous local controllers of fixed functionality to the central control unit. A second serial data link links at least a first dependent controller to electrical system controller. The electrical system controller provides for controlling multiplexing of signals on the first and second serial data links. Memory provides both protected and nonprotected sections, with the protected sections providing storage for configuration data structures residing in memory and the data structures providing functional definitions for the first dependent controller. A core program resides in memory for use with the data structures, and a central processor executes the core program using the data structures for generating control signals for transmission to the dependent controllers. The first dependent controller are responsive to the control signals for assuming specialized control states.

Description:
REFERENCE TO PRIOR APPLICATION 
     The present application is a continuation in part of Provisional Application No. 60/113,443 for Programming Input/Output Connections of Networked Interfaced Modules filed Dec. 23, 1998. 
     INCORPORATION BY REFERENCE OF RELATED APPLICATION 
     The present application is related to utility application Ser. No. 60/113,443 for Remote Interface Modules with Programmable Functions filed Dec. 23, 1998 and hereby expressly incorporates that application by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to multiplexing communication networks on vehicles and more particularly relates to providing a network having a central control module and one or more remote generic modules to provide control of non-standard vehicle vocations as well as specialized controllers for conventional vehicle vocations. 
     2. Description of the Prior Art 
     At a simple level, communication between two agents may be kept physically separated from communications occurring among other agents. Where two or more signals do not use the same physical space, there is no need to separate the signals in time or in carrier wave frequency. Such a communications regime is sometimes termed physical division multiplexing although the term multiplexing is usually reserved to techniques for applying multiple signals to a single medium or physical space. So called physical division multiplexing describes how motor vehicles have been traditionally wired. The use of separate dedicated wires to connect each switch and lamp is a type of physical division multiplexing. Obviously, physical division multiplexing, while simple in concept, results in the use of many wires (the classical motor vehicle electrical harness), which are difficult to install during manufacturing and problematic to maintain in the field. 
     Arrangements allowing a number of agents to communicate over a common physical layer or medium offer much greater physical simplicity. Intelligible communication between two or more devices among a greater plurality of devices, all over a common medium, depends upon the communicating devices being able to distinguish, and understand, messages directed to them from other messages which they receive, but which are not intended for them. The process of distinguishing messages depends upon the transmitter of the message applying some attribute to the message which identifies it to the intended recipient. In human conversation, most people readily distinguish speech directed to them from interfering crosstalk in a crowd by the distinctive aspects of the voice of the person addressing them. Where the members of the group are electrical components, the problem still involves identification of a distinguishing attribute of the signal. Appropriate attributes for signals take a number of forms. 
     A line communicating a signal from a remote switch to a lamp to turn on or off (by having a second switch, local to the lamp, change states to control connection of the lamp between a power bus and ground) cycles only rarely. In a typical trip such a change in state occurs only once or twice, if at all. Where such a line is not intended to provide power to the lamp, and simply indicates changes in state for the local switch controlling the lamp, the line will have the capacity to handle far more data than the occasional indications to turn a lamp on and off. The objective of maintaining simplicity in manufacturing and maintenance are preferably met by allowing communication among a number of components to occur in a single medium, or at least as few communication lines as possible. The line used to connect switch and lamp could interconnect a number of components, carrying messages between any grouping of elements connected to the line when not required to carry an instruction to a lamp to turn on. One way of achieving this objective is a communications regime which divides time into slots during which particular combinations of components have use of a signaling line. Such methods are well known in the art and are examples of time division multiplexing (TDM). In motor vehicles, time division and related multiplexing techniques offer substantial simplification in physical layer required to support the control of vehicle vocations. 
     Rigid time division multiplexed communications appear to interleave data signals into a single serial signal over a single physical medium. Multiplexed communication systems also provide the reverse function (demultiplexing) of dividing the single signal into multiple, nonsynchronous digital signals. Where demands on the capacity of the data transmission medium are not especially heavy, any unit may be allowed to claim the medium provided collision detection is provided for and other indicia, such as address headers, indicate the signal&#39;s destination. 
     As applied to motor vehicles, multiplexed communications over serial data paths are an effective technique for reducing the number of dedicated communication paths between the numerous switches, sensors, devices 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 communication serial 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 local controllers and switches for vehicle systems promises greater physical simplicity through displacing much of the vehicle wiring harness, reducing manufacturing costs, facilitating vehicle electrical load management, and enhancing system reliability. 
     The specific manner of implementing multiplexed communications is outside the scope of the present invention, which applies a defined protocol, the SAE J1939 protocol. 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. The J1939 protocol provides an open protocol and definition of the performance requirements of the medium of the physical layer, but also allows for development of proprietary protocols. The SAE J1939 protocol is a specialized application of a manufacturing costs, and anticipated improvements in reliability. Notwithstanding this recognition, the teaching of the Windle patent falls short of teaching a generalized physical layer in which numerous specialized functions are implemented by programming. 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. 
     Numerous advantages would flow from enabling a manufacturer to provide a chassis with a generalized electrical control layer on which programming could add extensive functionality. For example, builders of luxury coaches, 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. For example, a coach builder may wish to install a highly customized, zone activated air refrigeration system on a vehicle. Such specialized systems or vehicle vocations have required complex, customized wiring systems to support. Were a coach builder able to adapt a serial communication system to the functionality requirements of the various bodies, and further able to specify accessory functionality without the need to hardwire that functionality into the vehicle, substantial gains in physical simplicity and reliability could be achieved. 
     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. Such a generic control regime would allow greater differentiation in vehicles to be economically obtainable. 
     Windle et al. contemplated the use of fully reprogramable local controllers, which were adaptable to a defined sets of tasks by reprogramming. More recently, suppliers of major power train components have included a dedicated controller suitable for managing the component and for communicating with a vehicle electrical system controller using the open protocol of the J1939 standard. These suppliers allow a limited type of configuration programming of the controllers for changing the values of certain vehicle operating parameters. Configuration data has been used to change values of certain controlled parameters, such as engine horsepower/torque output curves, fuel rates and cruise control performance; however, the functional definition of the input and output interfaces of controllers have not been changed and the configuration programming continues to reside in the local controller. 
     SUMMARY OF THE INVENTION 
     An object of the invention is to provide a vehicle communications and control system supporting uniform physical layers across groups of vehicles of increasingly differentiated vocational requirements. 
     Another object of the invention is to minimize the number and variety of local controllers required in the physical layer to implement vehicle vocations. 
     It is a still further object of the invention to provide a physical layer for a communications and control system scalable through the use of scalable, functionally generic, local controllers, substantially relieving the communications and control system of input and output resource limitations. 
     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. The vehicle conventionally includes a plurality of drive train components, such as engines, transmissions and anti-lock brake systems to which electronic control is applied. Each major drive train component has its own autonomous controller, which executes a local program, but which responsive to requests received by the controller from a control network. Each autonomous controller includes means for receiving requests relating to a drive train component, and means for monitoring drive train component status in order to provide status indications for the component over the network including a first serial data bus to an electrical system controller. 
     The invention further includes at least one dependent controller for accessory components. The dependent controller includes a plurality of ports available for functional definition. The dependent controller includes a processor subject to remote control to specify all functions of the dependent controller. A second serial data bus connects the dependent controller and the electrical system controller. 
     The electrical system controller includes memory for storing a core program, definition data for the dependent controller and status indications received from both autonomous and dependent controllers. The core program and definition data are preferably stored in nonvolatile memory, but subject to being rewritten if required. The electrical system controller is based on a central processor connected by a bus to the memory for accessing and executing the core program on the definition data and on the status indications. Specific inputs to the dependent controllers are generated both to generate functional definition instructions for the dependent controllers and specific actions to take. The electrical system controller further includes serial bus controllers providing for multiplexing of functional definition instructions on the second serial data bus. 
     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 high level block diagram of the control network for a vehicle; 
     FIG. 3 is a diagrammatic depiction of the disposition of data interfaces for the central electrical system controller of the invention; 
     FIG. 4 is a detailed block diagram of the control network of the present invention; and 
     FIG. 5 is a schematic illustration of disposition of the control network of the present invention on a truck. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a perspective view of a vehicle electrical system  10  installed on a vehicle  13 . Vehicle control system  10  comprises an electrical 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 one of a group of autonomous, vocational controllers, which include a gauge cluster  14 , an engine controller  20 , a transmission controller  16 , an auxiliary instrument and switch bank  12 , and an antilock brake system (ABS) controller  22 , all of which are connected to ESC  30  over a serial data bus  18 . The autonomous controllers include local data processing and programming and are typically supplied by the manufacturer of the controlled equipment. Serial data link  18  is a twisted pair cable constructed in accordance with SAE standard J1939 and is externally accessible via a diagnostic port  36 . Although the autonomous controllers handle many functions locally and are functionally defined without reference to ESC  30 , they report data to ESC  30  and can receive operational requests from ESC  30 . 
     A second serial data link  42  extends from ESC  30  back to a remote interface module  40 . Remote interface module  40 , similarly to the autonomous controllers, provides local control signals to electrical devices constituting or controlling loads installed on vehicle  13 . While remote interface module  40  has data processing capability, it typically includes minimal local programming and is dependent on and functionally specified by signals received over the second serial data link  42  from ESC  30  for operation. Hence RIMs  40  are herein termed dependent controllers. 
     The loads imposed on vehicle  13  systems controlled by electrical control system  30  are usually electrical loads, however, they may include electronically controlled engagement of mechanical devices to the power train of vehicle  13 . Gear selection in an automatic transmission would be an example of such an arrangement. Other electrically controlled nonelectrical loads can include control of a clutch for an air conditioning compressor, or actuation of pumps driven by the vehicle drive train. The load management program can, depending on power demands by components, including accessories controlled by a RIM  40 , request increased power output from the engine through engine controller  20 . 
     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 RIM  40  is a general purpose control interface allowing the attachment of various accessories to vehicle  13 . RIM  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 the vehicle control system  10 . Electrical system controller  30  communicates with local vocational controllers over one of two major SAE J1939 serial data links  18  and  42 . The J1939 standard provides for both a open protocol and a proprietary protocol, which differ in the formatting of information transmitted over the serial data links. Accordingly, serial data links  18  and  42  may use the same or different communication protocols. Controllers for substantially common vehicle components such as transmissions, engines and the like communicate with ESC  30  over serial data link  18 , which utilizes a open protocol. A diagnostic connector  36  taps into serial data link  18  over which portions of the programming of ESC  30  may be overwritten. In the illustrated embodiment three remote interface modules are defined by ESC  30  over serial data link  42  to function as a remote power switch  40 (A), a remote engine controller  40 (B) and a remote air control system  40 (C). The specific functions of the several remote interface modules are unimportant and are given as examples only. Disposition of the control of major vehicle drive train components, the vehicle gauge cluster and the diagnostic port  36  onto serial data link  18 , and the provision of a second serial data link  42  for carrying communication among the definable, dependent controllers (remote interface modules  40 ) segregates major vehicle elements in a protected partition via link  18  which is isolated from operator defined functionality implemented over serial data link  42 . 
     ESC  30  also provided from monitoring several bi-state switches in a group of switch banks  51  over a relatively low baud rate SAE J1708 data link  52 . ESC  30  can also be directly connected to several devices and sensors directly, which are grouped as discrete outputs  53  and discrete inputs  55 . 
     FIG. 3 is a block diagram of the various elements of ESC  30 . ESC  30  includes a fixed number of interface connections for reading bi-state (i.e. on/off) switches. These inputs are appropriate for reading warning light sensors that typically provide a vehicle ground connection to indicate that the sensor is in an active state. An open circuit connection is provided by the sensor to indicate an inactive state. Another collection of inputs labeled analog inputs. These inputs are subject to sampling, analog to digital conversion and storage as a representative binary value in volatile random access memory section  63  of memory  60  for further processing. 
     A plurality of discrete output interfaces may include low power relay driver-connections that are capable of activating an electro-mechanical relay device located elsewhere on the vehicle and into the vehicle power distribution system (not shown). ESC  30  also provides high power solid state output channels. The high power output channels or power switches can handle up to a maximum of ten to twenty amperes at a battery voltage level of 14 volts. The direct input and output channels may be functionally defined by configuration programming of ESC  30 . If the number of channel interfaces is insufficient, one or more RIMs  40  are added to private serial data link  42 . 
     ESC  30  has three serial data interfaces including those to the two J1939 serial data links  18  and  42 . The J1939 serial data links operate at 250K baud data rates and, as described above, provide data communication between and among the major power train component autonomous controllers and ESC  30  on link  18  and between the dependent controllers and ESC  30  on link  42 . The Siemen C 167  Integrated Circuit provides two J1939 ports which are independently accessible and of which one is connected to the private J1939 link  42 . The public J1939 link  18  provides connection to the autonomous contender. In this way the definable RIMs  40  are segregated from the autonomous controllers, protecting the autonomous controllers from programming errors or faults occurring with respect to RIMs  40 . 
     Program memory  69  and most of the addresses of configuration data memory  65  are preferably constructed of flash memory allowing reprogramming of ESC  30  from diagnostic port  36  if required. Program memory  69  preferably requires high input voltages for rewriting, or is otherwise relatively protected compared to configuration data memory  65 . ESC  30  also functions as a data gateway between serial data link  18  and serial data link  42 . Serial data link  52  is a 9600 baud link in accordance with the SAE 1708 protocol. Volatile random access memory  63  provides a scratch pad for data from dependent controllers and sensor inputs. Boot-strap memory  67  loads the core operating program and configuration data. A central processing unit can address system memory for execution of the core program and utilization of the configuration data. The program stored in program memory  69  is not typically changed to accommodate the functional definition of either the ports of ESC  30  or RIMs  40 . The program is an event interruptable, looping algorithm which relies entirely on data tables stored in the configuration data memory section  65  to implement specific functionality on any physically undefined interface or port of ESC  30  or a RIM  40 . The data tables can be unique to a given vehicle, and relate port addresses to particular functionality and provide for vehicle response under defied conditions. 
     A RIM  40  may be constructed using digital signal processors or equivalent circuit elements. The methods of programming a digital signal processor to implement any number of circuit elements is well known in the art. ESC  30  must reliably implement various functions at particular ports of the RIM  40  and accordingly a standardized, expandable addressing scheme for each dependent controller and its respective I/O interfaces are provided. 
     FIG. 4 is a detailed schematic illustration of a physical layer for the invention. ESC  30 , located on the cabin side of firewall  92 , communicates with engine controller  20 , transmission controller  16  and anti-lock brake system  22 , and gauge display  14 , primarily over serial data link  18 . Selected bi-state switches in engine controller  20 , transmission controller  16  and ABS  22  may be controlled or monitored over serial data link  52 . Serial data link  42  provides communication between four dependent controllers or remote interface modules, on which ESC  30  implements an air solenoid drive  40 (D), a hydraulic solenoid drive  40 (E), a non-specified controller  40 (F) and a controller for remote lamps  40 (G). ESC  30  is directly connected to heater controls  75 , steering wheel switches  71 , and a driver control module  73  handling a plurality of other switches. The direct interfaces implemented by ESC  30  are also functionally defined by configuration programming. 
     FIG. 5 illustrates a possible physical layer for a vehicle control system including an ESC  30 , a plurality of RIMs  40 , and a plurality of autonomous controllers on a truck  13 . One RIM  40  is located at the exterior of cab  113 , providing a plurality of interfaces in the rear portion of truck  13 . A coach or vehicle body builder can define the interfaces to control a variety of optional or accessory equipment. The coach or vehicle body builder uses programming specifications to design a configuration data base to give the dependent controller functionality. A second RIM  40  may be positioned forward of the fire wall  92  on vehicle  13 . So positioned the second RIM  40  is conveniently situated to equipment added to the front end of a vehicle such as special lights or a positionable plow. 
     The invention enables implementation of a vehicle communications and control system having a uniform, but scalable, physical layer. Autonomous controllers, dependent controllers, central electrical system controllers and interconnecting data links can be physically identical from one vehicle to another across groups of vehicles of increasingly differentiated vocational requirements. The only physical difference, in many cases, will be the actual physical position on the vehicle which, from an electronic standpoint, provides a substantially uniform physical layer from vehicle to vehicle. Uniformity and scalability of the dependent controllers helps minimize the number and variety of local controllers required in the physical layer to implement vehicle vocations. The scalable implementation through the use of scalable, functionally generic, local controllers, and definable interfaces on the electrical system controller substantially relieves the communications and control system of input and output resource limitations. Scalability is further enhanced by providing a core program executable on scalable data tables which define the functionality of I/O ports. 
     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.