Communications: electrical – Land vehicle alarms or indicators
Reexamination Certificate
2000-09-11
2002-05-28
Wu, Daniel J. (Department: 2632)
Communications: electrical
Land vehicle alarms or indicators
C340S433000, C340S471000, C340S472000, C340S332000, C180S271000
Reexamination Certificate
active
06396395
ABSTRACT:
BACKGROUND OF THE INVENTION
School buses and to a lesser degree other people transportation vehicles have a number of components which need to be operated upon stops. For example upon stopping for passenger entry or exit egress, the driver of a school bus must operate flashing lights, foldable stop signs, bumper crossing arms, door openers, and parking brake of the vehicle. These requirements, most of them statutory, add demands upon the driver who is supposed to be watching out for passenger safety and operating the vehicle safely all at the same time. This invention relates to a system for a school bus or other people transportation vehicle that allows for one switch manual activation of all the stopping safety and warning lights and for automatic activation of all of these devices as sensed by vehicle position. Additionally, vehicle electronic controllers may be programmed to learn routes and all stops for which the automatic operation of the above safety and warning lights require operation. The system may be back-fit into a vehicle or programmed into controllers of a multiplexed electronic controller network. The invention also includes the steps of initiation and of learning routes, these steps recorded on tangible computer media.
PRIOR ART
School bus drivers must operate numerous safety and warning devices when they approach a stop to pick up passengers. This could potentially reduce the drivers ability to focus their full attention on the safety of the passengers, who may include children. In the prior art, the drivers of school buses had to individually operate all safety and warning devices, such as flashers, stop signs, crossing arms, door openers, and parking brakes manually.
Current vehicles have different forms of electronic communication networks. 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 cross-talk 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 that 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. The invention of this application involves one of those 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 (de-multiplexing) of dividing the single signal into multiple, non-synchronous 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'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 may apply a defined protocol, the SAE J1939 protocol or a proprietary protocols over a network similar to that described here. 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 controlled area network (CAN) and may be readily implemented utilizing commercial integrated circuits such as the C167 Integrated Circuit from Siemens of Germany.
A serial communications system utilizing a multiplexing regime can link several remote digital controllers or actuators or sensors 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. As described above the transmission ECM may be a
Hively Brad A.
Vandermolen Gary L.
Zielinski Andrew J.
Calfa Jeffrey P.
Pham Toan
Powell Neil T.
Sullivan Dennis Kelly
Wu Daniel J.
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