Patent Publication Number: US-2005143891-A1

Title: Vehicle dynamics control system

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a control system for a vehicle and, in particular, to a control system that uses the vehicle frame as a sensory input in controlling various components of the vehicle.  
      2. Discussion of Related Art  
      As electronic control of vehicles continues to evolve, numerous electronic control systems have been and are being developed to control conventional mechanical components of the vehicle. Electronic throttle control, electronic fuel injection, tire pressure management, and ABS brakes are just a few of the many examples of the use of electronic control systems in vehicles. Many conventional control systems, however, are restricted by the response times generated from sensor inputs. Further, conventional control systems often require the use of relatively expensive sensors.  
      The inventors herein have recognized a need for a vehicle control system that will minimize and/or eliminate one or more of the above-identified deficiencies.  
     SUMMARY OF THE INVENTION  
      The present invention provides a control system for a vehicle.  
      A control system in accordance with the present invention includes a plurality of sensor assemblies mounted on a frame of the vehicle. The sensors assemblies may be mounted in various locations on the frame of the vehicle and, in one embodiment, the sensor assemblies are mounted on the frame proximate each wheel of the vehicle and on front and rear cross members of the vehicle frame. Each of the sensor assemblies includes at least one strain sensor. The strain sensor generates a strain indicative signal indicative of strain on the vehicle frame. The control system further includes an electronic control unit (ECU). The ECU controls operation of a component of the vehicle responsive to the strain indicative signals generated by the strain sensors of the sensor assemblies. The vehicle component may, for example, comprise a throttle control valve or shock absorber.  
      A control system in accordance with the present invention represents a significant improvement as compared to conventional control systems. First, the use of the frame as a sensor substantially increases control response times of the control system. Second, the use of strain sensors provides a relatively inexpensive sensor arrangement. Third, the integration of the strain sensors and ECU into the vehicle structure will reduce assembly and inventory handling costs.  
      These and other advantages of this invention will become apparent to one skilled in the art from the following detailed description and the accompanying drawings illustrating features of this invention by way of example. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a perspective view of a portion of a vehicle incorporating a control system in accordance with the present invention.  
       FIGS. 2-4  are block diagrams illustrating power distribution and control in a control system in accordance with the present invention.  
       FIG. 5  is a block diagrams illustrating the interconnection of sensor assemblies and the electronic control unit of the inventive control system.  
       FIG. 6  is a block diagram illustrating a sensor assembly of the inventive control system.  
       FIG. 7  is a block diagram illustrating a control system in accordance with the present invention.  
    
    
     DETAILED DESCRIPTION OF ONE OR MORE EMBODIMENTS OF THE INVENTION  
      Referring now to the drawings wherein like reference numerals are used to identify identical components in the various views,  FIG. 1  illustrates a portion of a vehicle  10  incorporating one embodiment of a control system  12  in accordance with the present invention. Vehicle  10  may comprise any of a wide variety of conventional vehicles including, but not limited to automobiles, light and heavy trucks, and off-road vehicles. Among other components, vehicle  10  may include a frame  14 , axles  16 ,  18 , and wheels  20 , 22 , 24 , 26 .  
      Frame  14  is provided to support a conventional vehicle body on axles  16 ,  18 . Frame  14  is conventional in the art and may be made from conventional metals and metal alloys. In the illustrated embodiment, frame  14  includes a pair of spaced longitudinal rails  28 ,  30  extending in the direction of vehicle travel and in the longitudinal direction of vehicle  10  and several cross-members  32 ,  34 ,  36 ,  38 . It should be understood that the size, shape, and configuration of frame  14  will vary in accordance with various vehicle design parameters and the illustrated frame embodiment is not intended to limit the scope of the disclosed invention.  
      Rails  28 ,  30  are provided to secure and align the body (not shown) of vehicle  10  on frame  14  and are conventional in the art. The size, shape, and configuration of rails  28 ,  30  will vary depending upon design requirements associated with vehicle  10 .  
      Cross-members  32 ,  34 ,  36 ,  38  are provided to connect rails  28 ,  30  and to support other components of vehicle  10  (e.g., the engine). Members  32 ,  34 ,  36 ,  38  are conventional in the art and it should again be understood that the number of cross-members as well as the size, shape, and configuration of cross-members, may vary depending upon design requirements associated with vehicle  10 .  
      Axles  16 ,  18  are provided to rotatably support wheels  20 ,  22  and  24 ,  26 , respectively, and to support other components of vehicle  10  such as suspension and brake system components. Axles  16 ,  18  are conventional in the art and may be forged or otherwise formed from a variety of conventional metals and metal alloys. In the illustrated embodiment, axle  16  comprises a steer axle, while axle  18  comprises a drive axle. Although the illustrated vehicle includes only two axles, it should be understood that the present invention may find use in vehicles having any number and type of axle.  
      Wheels  20 ,  22 ,  24 ,  26  are provided to mount the tires and are conventional in the art. Wheels  20 ,  22 ,  24 ,  26  are rotatably supported on axles  16 ,  18  in a conventional manner. For example, wheels  20 ,  22  may be supported on a spindle extending from a steering knuckle (not shown) that is coupled to axle  16  through a conventional kingpin connection (not shown). Wheels  24 ,  26  may be supported on axle half shafts (not shown) driven by a differential (not shown) and extending from the housing of drive axle  18 . Wheels  22 ,  24 ,  26 ,  28  are also suspended from frame  14  by conventional suspension systems having components such as control arms, springs, and shock absorbers.  
      Control system  12  is provided to control one or more components of vehicle  10 . The components controlled may include, for example, the throttle valve (not shown), shock absorbers (not shown) or other suspension components, a torsion bar coupled to frame  14 , and brake systems (not shown). Control system  12  may also control components such as indicators that generate signals to the vehicle operator indicative of some characteristic of vehicle  10  such as tire pressure, balance, and shape, brake wear, vehicle load, and tongue weight. These indicators may be visual, audio, or a combination of the two, or may be designed to trigger other human senses (e.g., tactile senses through vibration). Control system  12  may include a power control assembly  40 , communication interfaces  42 , sensor assemblies  44   FL ,  44   FT ,  44   FR ,  44   RL ,  44   RT , and  44   RR  (collectively and generically identified by the numeral  44  hereinafter) and an electronic control unit (ECU)  46 .  
      Power control assembly  40  is provided to distribute power to sensor assemblies  44 . Referring to  FIG. 2 , assembly  40  may include a power supply  48  (such as a 12 volt or 42 volt battery), a plurality of power distribution modules  50   FL ,  50   FR ,  50   RI , and  50   RR , and a wiring harness  52  configured to distribute power from the power supply  48  to the power distribution modules  50  (collectively and generically identified by the numeral  44  hereinafter). Referring to  FIGS. 3-4 , each power distribution module  50  may include a conventional switching device  54  such as a smart field effect transistor that controls the flow of power from harness  52  to one or more sensor assemblies  44  responsive to a control signal from ECU  46 . A current estimate of the power required for each power distribution module  50  is 1200 watts, but as much as 4000 watts may be required. Each sensor assembly  44  is expected to require between three (3) and eight (8) volts for proper operation.  
      Communication interface  42  is provided to interface ECU  46  with other electronic control units in vehicle  10 . For example, ECU  46  may interface with the engine electronic control unit, the electronic control unit for the braking system, and the electronic control unit used to send and receive vehicle operator information. Interface  42  is conventional in the art and may include one or more wiring harnesses incorporating twisted pair cables as well as connectors at various termination points on the harness.  
      Sensor assemblies  44  are provided to transmit signals to ECU  46  indicative of the strain on frame  14  of vehicle  10 . Referring to  FIG. 1 , assemblies  44  may be disposed in a variety of locations relative to frame  14 . In one embodiment of the invention, sensor assemblies  44   FL ,  44   RL , and  44   FR ,  44   RR  are disposed on rails  28  and  30 , respectively, of frame  14 , proximate each wheel  20 ,  22 ,  24 ,  26  of vehicle  10 , and sensor assemblies  44   FT ,  44   RT , are disposed on cross-members  32 ,  38  of frame  14 . Referring to  FIG. 5 , a wiring harness  56  may be used to route signals between sensor assemblies  44  and ECU  46 . The harness  56  may incorporate twisted pair cables. Referring now to  FIG. 6 , each sensor assembly  44  may include a sensor package  58  including a plurality of strain sensors  60  and an integrated electronics package  62 , and means, such as mounting plate  64 , for mounting assembly  44  to frame  14 .  
      Strain sensors  60  are provided to indicate strain on areas of frame  14 . Sensors  60  are conventional in the art may be formed from silicone using micro machining technology. In the illustrated embodiment, each sensor assembly  44  includes four strain sensors  60 , although it will be understood that the number of strain sensors  60  may vary. The strain sensors  60  in each assembly  44  are redundant and bridged to provide common mode noise rejection. Sensors  60  generate strain indicative signals indicative of the strain on frame  14 .  
      Package  62  is provided to condition and potentially process the strain indicative signals generated by sensors  60 . Package  62  may include conventional circuitry for impedance matching, amplification, conditioning, summing, and analog to digital conversion. Package  62  may also include a digital signal processor for preprocessing signals prior to delivery to ECU  46 .  
      Mounting plate  64  is provided to mount sensor assembly  44  to frame  14 . Plate  64  may comprise a metal substrate to which sensor package  58  is bonded. Plate  64  may be coupled to frame  14  using conventional fasteners (not shown) or by welding.  
      Referring now to  FIG. 7 , ECU  46  is provided to generate control signals used to control one or more components of vehicle  10  responsive to the strain indicative signals generated by sensor assemblies  44 . ECU  46  may comprise a programmable microprocessor or microcontroller or may comprise an application specific integrated circuit (ASIC). ECU  46  may include conventional components such as a central processing unit (CPU), an input/output (I/O) interface and memory. ECU  46  may be configured to process input signals and generate output signals used to control components of vehicle  10  by programming instructions or code (i.e. software). These instructions may be encoded on a computer storage medium such as a conventional diskette or CD-ROM and may be copied into the memory of ECU using conventional computing devices and methods.  
      ECU  46  receives inputs from each of sensor assemblies  44 . In addition, ECU  46  may receive input signals from other conventional vehicle sensors and use these input signals together with the strain indicative signals to control components of vehicle  10 . For example, ECU  10  may receive a steering angle indicative signal from a steering angle sensor  66 , a speed indicative signal from a vehicle speed sensor  68 , an acceleration indicative signal from an accelerometer  70 , a brake signal from a wheel end ABS sensor  72 , and a throttle position indicative signal from a throttle position sensor  74 . Those of skill in the art will understand that signals generated by other conventional vehicle sensors may be input to ECU  46  as well for use in controlling components of vehicle  10 .  
      ECU  46  generates one or more control signals used to control various components of vehicle  10 . As set forth hereinabove, the components controlled by ECU  46  may include a throttle valve  76 , ABS braking systems  78 , shock absorbers  80  or other suspension components, a torsion bar  82 , or various indicators  84  for the vehicle operator. Through control of such components, system  12  is able to exercise control over vehicle stability, rollover protection systems, ride height, and active suspension damping. The programming instructions or code for ECU  46  may be written in a modular format to enable potential customers to purchase controls for individual vehicle components (e.g., a shock absorber) or vehicle characteristics (e.g., rollover protection). The modular format is advantageous in allowing a manufacturer to offer for sale and manufacture vehicles having only those control features the customer wants.  
      A control system in accordance with the present invention represents a significant improvement as compared to conventional vehicle control systems. In particular, the inventive control system increases the response time for controlling various vehicle components from sensor inputs by integrating strain sensors into the vehicle frame and using the vehicle frame itself as a sensor. The inventive system also is relatively inexpensive. In particular, the use of strain sensors provides a less costly alternative to sensors more commonly used in vehicle control systems today. Further, the integration of the sensors into the vehicle frame will reduce assembly and inventory handling costs.  
      While the invention has been shown and described with reference to one or more particular embodiments thereof, it will be understood by those of skill in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.