Abstract:
A processor-based system may be utilized to analyze signals from at least two supports supporting a device, such as a motor vehicle, to provide an indication when a weight change is such that tipping or rollover of the device or vehicle is of concern. In this way, an early warning may be provided when a condition arises which may cause a dangerous event to occur. The processor-based system may provide a variety of indications of tipping levels, a variety of different types of warnings and information about how to overcome the potential tipping.

Description:
BACKGROUND 
     This invention relates generally to devices which indicate incipient tipping or rollover of a machine such as a vehicle. 
     Tipping occurs when the center of gravity of a freestanding object shifts so that it is no longer within the perimeter defined by the elements that support the object. In a number of cases, there is a need to know when a machine is about to tip over. For example, when a motor vehicle is about to tip over, the operator may be warned to avoid rollover and potential injury. The possibility of rollover is a real problem for a number of commercial vehicles such as large tractor trailer trucks. Tipping or rollover may also occur with a variety of recreational vehicles such as sport utility vehicles, motorcycles and off-road vehicles such as dune buggies. 
     Tipping may be a problem not only in connection with motor vehicles but also in connection with large commercial cranes, such as construction cranes and cranes that are utilized to unload ships. Because of the large cantilevered forces applied by the crane, a tipping condition may occur unexpectedly. 
     Tipping may be result of centrifugal forces applied to a machine such as a vehicle during a turn. Tipping also may be the result of disturbances, such as high winds or impacts. A variety of circumstances may arise which may, to varying degrees of predictability, cause a given device having a given characteristic to turn over. 
     Thus, there is a need to detect when a device may tip over so as to enable intervention and tipping prevention. 
     SUMMARY 
     In accordance with one aspect, a method of detecting tipping of a device includes obtaining an indication of the force applied to at least two supports for the device. A change in an indication of the force applied to one of the supports is detected. A determination is made as to whether the change exceeds a threshold and a tilt indication is provided. 
     Other aspects are set forth in the accompanying detailed description and claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a top view of one embodiment of the present invention; 
     FIG. 2 is a depiction of the computer display, shown in FIG. 1, in accordance with one embodiment of the present invention; 
     FIG. 3 is a flow chart for software for implementing one embodiment of the present invention; and 
     FIG. 4 is a block diagram of hardware for implementing one embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, a device  10  that may be subject to tipping is illustrated in the form of a so-called skid loader. A skid loader is a vehicle prone to tipping because of its small size and its large load carrying capabilities. However, the present invention is in no way limited to skid loaders and may be applied to commercial and recreational vehicles, and to a variety of equipment subjected to forces that may cause tipping. 
     The device  10  includes a set of four weight supports  12  which may be wheels connected by a body  16 . The device  10  also includes a front loader  14  in one embodiment of the invention. Thus, the forces which cause tipping may result in an unbalanced weight condition, created for example by a large force applied through the front loader  14 . 
     However, regardless of the source of the force, tipping may be detected by monitoring the pressure on some or all of the supports  12  that support the device  10 . By monitoring the relative amount of weight being carried by each support  12 , an indication of tipping likelihood may be obtained. 
     At the point of tipping, one or more supports  12  may no longer bear any weight at all. As the weight shifts from a support  12 , from an evenly balanced distribution, eventually a predetermined point is reached wherein it may be desirable to warn an operator or user of the impending possibility of tipping. The user may then take corrective action to reduce the tipping possibility. 
     If the user fails to take corrective action, a subsequent warning may be provided when the indication of the force applied to any of the supports falls below still a further level. Ideally, this level is sufficiently low to avoid unnecessarily interfering with the operation of the device  10  while at the same time providing an adequate safety margin to give the user or operator adequate time to avoid tipping. 
     To provide this information in a prompt fashion, a set of sensors  18  may be provided in association with each of the supports  12  in one embodiment of the present invention. The sensors  18  may be applied in connection with bearings or axles utilized to support the wheels. In one embodiment of the invention, the sensors  18  maybe load cells that provide an indication of the portion of the weight of the overall device  10  borne by each support  12 . 
     Coupled to each of the sensors  18  is a microcontroller  20 . The microcontroller  20  may also be coupled to a display  22  arranged proximate to an operator. 
     The microcontroller  20  may respond not only to a given change in the amount of weight on any given support  12 , but may also respond to a rate of change which is sufficiently excessive to raise a tipping concern. Thus, if the rate of change is sufficiently high, the system may determine that an immediate warning may be issued. Otherwise sufficient time to provide a warning may not be available. Thus, in one embodiment of the present invention, the microcontroller  20  may provide tipping indication either when the rate of change of weight on a given support  12  exceeds a given rate of change threshold or when the disparity in forces applied to one support compared to another support indicates that a tipping condition may arise. 
     Referring to FIG. 2, the display  22  may provide a simple graphical user interface which facilitates prompt response to the tipping situation. For example, in the case of a skid loader, a depiction of the vehicle may be provided as indicated at  24  showing the detected direction of incipient tipping. A graphical display  26  may also indicate the direction of tipping. Thus, given the display shown in FIG. 2, the user may slow down and turn to the left to attempt to stabilize the device  10 . A variety of different graphical user displays may be provided based on the extent and direction of potential tipping which has been detected. 
     As shown in FIG. 3, software  28  may be utilized to monitor the sensors  18  and to provide an early warning of potential tipping situations. Initially, all the sensors may be checked, as indicated in block  30 , to be sure that each sensor  18  provides a signal. If the weight detected by any of the sensors falls below a given level, indicated as X in diamond  32 , a warning may be issued as indicated in block  34 . 
     If the weight falls below an alarm level on any one of the supports  12 , such as the level X+Y, an alarm may issued as indicated in block  38 . The alarm may provide more urgency than the warning indicated by block  34 . 
     In some embodiments of the present invention, a check may also determine whether the rate of change is sufficiently severe to necessitate a warning. In such case, a variety of different notifications may be provided which may be recognized by the user or operator. For example, different audible indications may be provided for a warning, an alarm, or a rate of change indication. 
     Referring to FIG. 4, one embodiment for implementing the present invention may use a conventional microcontroller  20  coupled to a storage device  40  such as a flash memory. The storage device  40  may store the software  28 . Alternatively, the software  28  may be preprogrammed into the microcontroller using conventional microcontroller programming techniques. The microcontroller  20  may be coupled to the display  22  and to a horn or audible warning device  42 . Similarly, each of the sensors  18  may be coupled to the microcontroller  20 . 
     The microcontroller  20  may be responsible for analyzing the levels provided by the sensors  18  and in some embodiments of the present invention, the rate of change of levels detected by each of the sensors  18 . When a tipping condition is detected, the microcontroller  20  may provide a display on the display  22 , as shown in FIG. 2, or audible indications using the audible warning device  42 . 
     In still other embodiments, the microcontroller  20  may automatically take corrective action. For example, if the appropriate action is to slow the device down, the microcontroller may immediately apply braking. Similarly, the microcontroller  20  may institute other corrective actions such as lowering the front loader, causing a vehicle to turn, providing a weight shift, changing the position of a crane or any of a variety of other appropriate corrective actions. 
     While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.