Abstract:
Control over school bus warning lights and its cross over arm are implemented through pre-existing steering wheel mounted speed control switches with minimum modification of vehicle hardware.

Description:
BACKGROUND OF THE INVENTION 
   1. Technical Field 
   The invention relates to motor vehicle controls and more particularly to controls relating to specialized or auxiliary equipment for special purpose vehicles, such as passenger embarkation/disembarkation warning systems for school busses. 
   2. Description of the Problem 
   Driver controls for motor vehicles are better positioned if consideration is given to the tasks and distractions likely to be confronting the driver while using the controls. A consequence of such considerations is that motor vehicle designers now commonly locate speed control switches on the vehicle&#39;s steering wheel. A driver is likely to be maneuvering the vehicle when activating and deactivating the speed control system or when adjusting the settings of the speed control system. It is undesirable that the driver be distracted from driving by removing his hands from the steering wheel while doing so. 
   Depending upon the intended use of a vehicle, different criteria might govern the placement of controls. Of particular interest to the present invention are how the activities of a bus driver, particularly a school bus driver, might influence the choice of control location. Analysis of school bus drivers&#39; activities behind the wheel has indicated that, as might be expected, that the activation of door controls, warning lights and stop arms demands the most hand movements. 
   The control electronics for contemporary motor vehicles make increasing use of programmable, digital electronics to receive driver inputs from control switches and to route control signals to devices. The switches on the vehicle steering wheel are no longer typically hard wired to the devices they control, but rather the outputs from the switches are interpreted by a digital computer and the appropriate control signals generated and routed to a controller for the intended device. This eases decisions regarding the location of switches since wires do not have to be routed from switch to controlled device. It also means that the functions of particular switches are not necessarily fixed. The Society of Automotive Engineers (SAE) has published standards relating to motor vehicle digital control networks and communications, including the J1708 and J1939 standards. 
   SUMMARY OF THE INVENTION 
   According to the invention there is provided a motor vehicle having a steering wheel and a plurality of control switches mounted on the steering wheel and accessible to a driver handling the steering wheel. The motor vehicle is further equipped with a stop arm extendible from a side of the motor vehicle and warning lights mounted with respect to the exterior of the motor vehicle. A body computer is installed to receive driver input through various switches including the plurality of switches installed on the steering wheel. The body computer is programmed to respond to the signals to control the state of activation of the warning lights and for controlling positioning of the stop arm. The motor vehicle may further include a passenger door which is positioned using compressed air or a motor. The body computer may be further programmed to respond to one of the plurality of switches to generate a control signal for positioning the door in opened and closed positions. 
   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 school bus on which the present invention is advantageously practiced. 
       FIG. 2  is a school bus in the bumper integrated safety arm in a retracted position. 
       FIG. 3  illustrates the safety arm of  FIG. 2  in an extended position. 
       FIG. 4  is a perspective view of driver controls for the bus of FIG.  1 . 
       FIG. 5  is a front elevation of a steering wheel for the bus of FIG.  1 . 
       FIG. 6  is a circuit schematic block diagram illustrating control arrangements for steering wheel mounted switches. 
       FIG. 7  is a circuit diagram of the steering wheel switches of FIG.  6 . 
       FIG. 8  is a flow chart illustrating cross over lights and crossing arm operation. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to the figures and in particular to  FIG. 1 , a school bus  10  is illustrated in perspective view. School bus  10  comprises a body  12  on the exterior of which are mounted various warning lights  20 , which may flash either amber or red, and a stop arm  18 , which swings outwardly from the driver&#39;s side  14  of school bus  10  when needed. A passenger door  16  is illustrated as disposed on the opposite side of school bus  10  from stop arm  18 , although in some jurisdictions, the door  16  and stop arm  18  may be on the same side of the vehicle. 
     FIGS. 2 and 3  illustrate a safety crossing arm  11  which may be used with the invention. School bus  10  may carry safety crossing arm  11  installed in a bumper  17 . Bumper  17  is formed with a generally rectangular opening  15  through which a pivot mount  19  extends. Safety crossing arm  17  is mounted on pivot mount  19  to swing member  13  outwardly during use. A safety crossing arm suitable for inclusion on Bus  10  is disclosed in U.S. Pat. No. 6,213,526, which is incorporated herein by reference. 
   Referring to  FIG. 4 , an instrument panel  22  and associated supplemental control panel  24  are illustrated. Instrument panel  22  and supplemental control panel  24  mount a variety of switches used by a driver who sits behind the panels to control various vehicle functions. In addition a steering wheel  26  is positioned spaced from instrument panel  22  for use of a driver for steering school bus  10 . 
   Referring to  FIG. 5 , steering wheel  26  is illustrated in greater detail. An array of switches are installed on steering wheel cross member  29  which is disposed across an interior chord of perimeter grip  27 . Most of the switches are positioned to allow the driver to actuate the switches without moving his hands from the perimeter grip  27 . The driver actuates the switches without moving his hands include an air horn button  36 , a door open button  28 , a door close button  30 , an amber warning light flasher actuation button  32  and a red warning light flasher actuation button  34 . In addition, a city horn button  38  is placed in the center of cross member  38 . Door open button  28 , door close button  30 , amber warning light flasher button  32  and red warning light flasher button  34  utilize switches originally provided for a speed control system. The switches are readily relabeled for use in controlling the various warning functions. The speed control functions, if retained on the vehicle, maybe moved in turn to the supplemental control panel  24 . Crossing arm and stop arm control are implemented as actions responsive, in part, to the warning light control buttons. 
   Referring to  FIG. 6  a circuit schematic illustrates implementation of control over school bus warning features using switches originally incorporated on the vehicle for a speed control system. A body computer  40  is a programmable computer with broad responsibilities for vehicle operations. Body computer  40  communicates with various vehicle electrical components, either by a direct connection or over a data bus. At least two types of databus are present including an SAE J1708 databus  64  and an SAE J1939 databus implemented using controller area network (CAN) controllers  68 ,  70 . The J1939 bus (also called a data link) carries high data rate data between body computer  40  and other controllers such as an engine controller (not shown) and an automatic transmission controller  66 . Among the data received over the J1939 databus is indication of the transmission position, e.g. whether the transmission is in park. The J1708 bus  64  handles low data rate communications between body computer  40  and switch packs  62 . The array  60  of steering wheel switches provides inputs directly to a vehicle body computer  40 . Body computer  60  is also connected to receive directly input state signals relating to the position of a parking brake. Body computer  60  also provides signals controlling a plurality of FET switches  42 ,  44 ,  46 ,  48  and  49 . The FET switches may be cycled on and off, such as FET switches  42 ,  48  for causing amber warning lights  50  and red warning lights  56 , respectively, to flash on and off. FET switches  44 ,  46  are activated to operate a stop arm extension and retraction motor  52  and a valve solenoid  54  controlling the opening and closing of passenger door  16 , respectively. Fet  49  controls activation of a cross arm extension motor  47 . Some speed control functionality formerly implemented through steering wheel switch array  60  may be moved to one of the six pack switch sets  62  if retained. 
   The operation of the warning lights  50 ,  56 , passenger door  16 , arm extension motor  52  and crossing arm extension motor  47  depend not only a operator manipulation of switches in switch array  60  but may also depend upon the status of the vehicle transmission and vehicle parking brake. For example, some State laws may require setting the park brake before allowing children to board or disembark from the bus  10 . If so, body computer  40  may be programmed to permit the passenger door to open and close, when the warning lights have been activated, only if the park brake  90  is set. Similarly, data from the transmission controller  66  may be interrogated to determine if the transmission is in park or if the engine speed is zero. 
   Referring to  FIG. 7  a conventional switch array  60  such as normally used to implement steering wheel mounted controls for a speed control system for a medium duty truck and adapted to implement the present invention is shown. Switch array  60  conventionally includes switches for a city horn, an air horn, an off switch, an on switch, a speed set switch and a resume switch. All of the switches are momentary contact switches, opening after being depressed by an operator. The on, set and resume switches are each connected in series with a resistor. The off, on, set and resume switches are tied to a common node which is connected through a steering column interface  72  to the body controller/system controller  40 . The resistors differ in value allowing determination, on account of differing current, of which of the four switches are in use. Assignment of a particular function to a switch is arbitrary. The functionality of the air horn and city horn switches is not changed. 
   Referring now to  FIG. 8 , a flow chart is used to illustrate operation of a preferred embodiment of the invention. Operation of the warning system depends initially on the driver activating the amber warning lights as indicated at step  100 . If the lights are not activated, driver depression of the door open button  28  (step  126 ) is not accompanied by activation of any other warning device. Accordingly the red cross-over warning lights, crossing arm and stop arm (steps  128 ,  130  and  132 ) are all off, allowing the driver to exit the bus (step  134 ). 
   The embarkation/disembarkation of children from school bus  10  can be done with the warning system in an automated mode  102  or a semi-automated mode  104 . Operation of the warning system is entered whenever the amber warning lights are activated (step  100 ). In the semi-automated mode the stop arm  18  and crossing arm  11  are activated (steps  118 ,  120 ) in response to the driver activating the red cross-over lights (step  106 ). The driver then opens the door (step  122 ) and children can enter or exit the bus (step  124 ). In automated mode the driver activates the red warning lights (step  106 ) and then, upon his actuating the door (step  108 ) the red warning lights turn on (step  110 ), and the crossing arm and stop arm extend (steps  112 ,  114 ). Children may then enter or exit the bus. 
   The present invention provides a low cost adaptation of speed control switches for another function in an environment where speed control functions are of less importance or not provided at all. Further, driver handling of warning light/arm features of a school bus are moved to the steering wheel of the school bus eliminating the need for the driver to move his/her hands from the wheel. 
   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.