Abstract: Impending rollover events are detected by recognizing a plow phase increase in lateral acceleration, coupled with a significant trip phase roll rate. The plow phase increase is recognized by modeling a typical soil trip lateral acceleration characteristic and computing a cross-correlation between the measured lateral acceleration and the modeled acceleration. The correlation is compared to a threshold that varies with the measured roll rate to reliably discriminate rollover events from near-rollover events while enabling timely deployment of suitable occupant restraints.

Abstract: In a method and a device for preventively actuating a vehicle occupant protection means in a vehicle having a vehicle movement dynamics control system, the vehicle occupant protection elements can be activated before a collision time and thus placed in an operative position. An evaluation variable relating to a state of “oversteering” is monitored, and when the state of “oversteering” is identified the vehicle occupant protection elements are activated. The evaluation variable for monitoring the state of “oversteering” is determined by using a manipulated variable of the vehicle movement dynamics control system.

Abstract: Disclosed are a method and a device for operating an in-automobile device through an existing security system of an automobile. The device includes a controller that includes a CPU based control circuit connected to a radio frequency receiver circuit, a power supply and voltage regulation circuit, and a relay switching system. The controller is electrically connected to control circuits of in-automobile devices so that the controller can be controlled by a remote controller of the security system of the automobile to effect operation of the in-automobile device and to enhance functionality of the in-automobile devices and the security system of the automobile.

Abstract: A seat belt retractor system for a vehicle having a vehicle safety system. The seat belt is retracted at a faster rate when a threat is detected using a high-voltage generated by a local power source.

Abstract: Vehicle with an occupant safety system for use in a crash involving the vehicle includes an occupant protection device, an inertial measurement unit (IMU) arranged to measure acceleration of the vehicle in three orthogonal directions and angular velocity of the vehicle about three orthogonal axes, the accelerations and angular velocities being measured at a substantially common location, and a processor coupled to the IMU for receiving the measured acceleration of the vehicle and the measured angular velocity of the vehicle. The processor determines whether the vehicle is experiencing a crash, and specifically, a rollover, and if so determines whether actuation of the occupant protection device is beneficial. If actuation is deemed beneficial, the processor generate a signal to actuation of the occupant protection device. The occupant protection device may be an inflatable airbag.

Abstract: A vehicle data recorder according to an embodiment of the present invention comprises a processor, a power supply, a program memory for storing directions to be executed by the processor, a video camera for recording video data, a random-access memory for storing video data received from the video camera in a continuous-loop fashion, a non-volatile memory for storing video data from the random-access memory in response to a triggering event, a first sensor for detecting a triggering event, and a video display, wherein the video display displays video stored in the non-volatile memory, and wherein the vehicle data recorder is detachable from the motor vehicle and is capable of playing back video stored in the non-volatile memory while detached from the motor vehicle.

Abstract: A method and a system in the classification of objects occupying a seat, in particular for the reliable control of the triggering of restraint systems in motor vehicles. Utilized are the dynamics of a person seated on the seat, based on the acceleration forces acting on the person. Using the variables of these forces and the force exerted on the seat cushion of the seat by the mass of the person and its change, there is a determination, as a redundant variable, the mass, the location of the center mass and other physical variables and these are used for the reliable classification.

Abstract: A control system includes a temperature sensor, an occupant detector, and a responsive circuit for activating a warning horn or to provide ventilation when an occupant is sensed in a dangerously hot passenger compartment. The circuit is passively actuated, such as by using a switch system incorporating a shape memory alloy (SMA) wire or a bimetal switch, in order to control temperatures in the passenger compartment or trunk of vehicles, such as when the vehicle is parked in the sun. The thermal switch actuates an occupant sensor using remote accessory power from the vehicle's battery, yet without creating an unacceptable phantom current drain on the vehicle's battery. Shape memory alloy wire contracts when temperature reaches a predetermined intolerable temperature in a vehicle, thereby closing a normally open switch contact to complete an electrical circuit.

Abstract: An occupant protection system for a motor vehicle includes at least one crash sensor for measuring a motion variable. The occupant protection system includes an occupant protection device, controlled by an ignition signal, and a control device for determining the ignition signal subject to an average time value of the motion variable measured by the crash sensor during at least one first time interval.

Abstract: Externally deployed airbag system for a vehicle including one or more inflatable airbags deployable outside of the vehicle, an anticipatory sensor system for assessing the probable severity of an impact involving the vehicle based on data obtained prior to the impact and initiating inflation of the airbag(s) in the event an impact above a threshold severity is assessed, and an inflator coupled to the anticipatory sensor system and the airbag for inflating the airbag when initiated by the anticipatory sensor system. The airbag may be housed in a module mounted along a side of the vehicle, in a side door of the vehicle (both for side impact protection), at a front of the vehicle (for frontal impact protection) or at a rear of the vehicle (for rear impact protection). Also, the externally deployed airbag can be deployed to cushion a pedestrian's impact against the vehicle.

Abstract: Systems for detecting animate objects in a vehicle compartment include active materials based sensors for detecting the presence of an animate object in the compartment. The systems produce a response if the sensors detect the presence of an animate object in the compartment and at least one other predetermined condition exists.

Abstract: Method for the evaluating of an installation location of an acceleration sensor assembly in a vehicle with respect to the transmission characteristics to this installation location of acceleration impulses acting on the vehicle, with a following serially-connected evaluating circuit, especially for the triggering of occupant protection devices, in that a prescribed acceleration impulse is impressed at at least one prescribed position on the vehicle, the impulse response is measured at the installation location, the frequency spectrum of the impulse response is determined, and the installation location is evaluated through comparison of this frequency spectrum with a prescribed nominal spectrum.

Abstract: A collision determination is made by using at least one of the output signals of a front G sensor disposed on a vehicle's fore-end and an analog G sensor disposed within the vehicle interior; a safety determination is made by using at least one of the output signals of the analog G sensor, the front G sensor, and a safing G sensor; and when both of the collision determining signal and the safing signal indicate the significance, an application specific IC and a transistor switch actuate a squib activating an air bag.

Abstract: An apparatus (10) for controlling a multistage actuatable occupant restraining system (14, 18) of a vehicle includes a crash sensor (32) sensing crash acceleration at a substantially central location of the vehicle. A crush zone accelerometer (40, 42) is provides a crush zone crash acceleration signal. A controller (50) a crash velocity value and a crash displacement value in response to the crash acceleration signal. A plurality a predetermined crash velocity as a function of crash displacement threshold maps (152-172) is provided, two of the plurality of threshold maps (170, 172) relating to a second stage (92, 96) of said multistage actuatable occupant restraining system. The selects one of the two threshold maps relating to the second stage of in response to the crush zone acceleration signal and controls second stage actuation in response to a comparison of the crash velocity signal against the selected one of the two threshold maps (170, 172).

Abstract: A unified approach that permits the consideration of different issues and problems that affect driving safety. Particularly, there is proposed herein the creation of a driver safety manager (DSM). The driver safety manager embraces numerous different factors, multimodal data, processes, internal and external systems and the like associated with driving.

Abstract: A rollover detection system for a vehicle comprises at least one sensor for the detection of the angle of rotation of the vehicle and/or at least one angular rate sensor, an electronic control device connected to the sensors as well as at least one safety device which can be activated via the control device in the event of a rollover scenario detected with reference to the sensor data. At least one irreversible safety device and at least one reversible safety device are provided. The control device distinguishes between at least one stage of a lower degree of severity and at least one stage of a higher degree of severity of the rollover scenario in the detection of a respective rollover scenario with reference to the sensor data in order to activate at least one reversible safety device in the case of a lower degree of severity and to activate at least one irreversible safety device in the case of a higher degree of severity.

Abstract: The invention relates to a method and to an arrangement for eliminating false messages in monitoring systems for electronic devices, especially for sensor circuits in motor vehicles. According to the inventive method, error messages increment a counter and an alarm is triggered when a predetermined position on the counter is reached.

Abstract: A wireless system that detects the presence of a child in a safety seat located in the passenger cabin of a vehicle includes a controller responsive to signals generated by sensors monitoring predefined functions of the vehicle, RFID tag device attached to the safety seat and RFID tag reader mounted in the cabin. The system generates control signals which activate an alarm, open the doors of the vehicle and roll down windows if the child is left in the safety seat of an unattended vehicle.

Abstract: A vision-based occupant classification method utilizes a static classification routine for achieving highly accurate occupant classification, a dynamic detection routine for quickly responding to changes in occupant position, and a category state change routine for detecting potential changes in occupant category. The static classification routine determines an initial classification of the occupant, after which the dynamic detection routine monitors for changes in occupant position and the category state change routine monitors for a potential change in occupant category. If category state change routine detects a potential change in occupant category, the static classification routine is re-executed to re-classify the occupant. The category state change routine identifies a composite optical flow vector associated with occupant movement, and detects a potential change in occupant category when the composite flow vector crosses one or more pre-defined entry/exit motion gates.

Abstract: A vehicle tracking unit preferably includes a vehicle position determining device, a wireless communications device, and a controller connected to the wireless communications device and the vehicle position determining device. The controller preferably cooperates with the wireless communications device to generate a sequence of alert message notifications for the user, and for canceling any remaining alert message notification of the sequence based upon a cancellation command response from the user having already received the alert message notification.

Abstract: An apparatus for driving an occupant-protecting airbag device mounted on a vehicle is provided. The airbag device includes an airbag and a squib and the squib can be deployed by igniting the squib. The apparatus comprise plural sensors, plural A/D converters, a determination unit and an ignition circuit. Each sensor senses a physical quantity acting on the vehicle to output an analog signal indicative of the physical quantity. Each of the plural A/D converters is electrically connected to at least one of the plurality of sensors to cause each A/D converter to perform an A/D conversion on the signal. The determination unit uses the signal converted by each A/D converter to determine whether or not the airbag should be deployed. The ignition circuit causes the squib to ignite to deploy the airbag when the determination unit determines that the airbag should be deployed.

Abstract: An apparatus for detecting impact of a moving object, in particular of a vehicle, having a first sensor device for acquiring an acceleration in a direction of motion of the moving object, an evaluation device for evaluating the first acceleration signal, and at least one second sensor device for acquiring an acceleration in an acquisition direction that is different from the direction of motion of the moving object, a classification of an impact by way of a classification signal being made available as a function of accelerations in at least two directions of motion or three acceleration directions.

Abstract: A multimedia racing experience system is provided including a plurality of input devices, such as cameras, microphones, and telemetry sensors. All input devices communicate with an on-vehicle processing unit for multiplexing the input data into a data stream. The data stream is then transferred to a central location for display or recording on playback media.

Abstract: Disclosed is a device for measuring accelerations for a vehicle passenger protection system, whereby a first and second acceleration sensor with a first or second sensitivity direction are fitted in relation to a prespecified main direction of measurement, which form a first or second transverse projection in their projection onto a first or second transverse direction which is aligned vertically to the main direction of measurement, together with suitable evaluation devices for evaluating the processed first and second measuring signals. The first and second transverse projection of the first and second sensitivity directions run parallel to each other, and the first and second main projection of the first and second sensitivity direction run antiparallel to each other. Furthermore, the evaluation of the measured values provided by the sensors is conducted in such a manner that at least a partial error compensation results when the reference value changes in relation to the first and the second signal.

Abstract: In a rollover judging device for a vehicle, an acceleration differential value of an acceleration of a vehicle in a lateral direction is calculated. And a roll angle of the vehicle is calculated from a roll rate. Then, the acceleration differential value is compared with a predetermined value corresponding to respective roll angles, to judge a trip-type rollover of the vehicle.

Abstract: A vehicle crash safety system includes a pre-crash sensing system generating an object threat assessment and vehicle dynamics data, an occupant sensing system generating occupant characteristic data, and an Occupant Safety Reference Model (OSRM) controller for generating a reference safety restraint deployment profile as a function of the object threat assessment, vehicle dynamics data and occupant characteristic data. An active restraint adaptation (ARA) controller in operative communication with the OSRM controller and a decentralized restraint controller. The ARA controller sends restraint deployment targets, and the safety restraint deployment profile to the decentralized restraint controller. The ARA controller may modify input signals to the decentralized controller based on the real-time occupant position trajectory. The decentralized restraint controller is adapted to operate the restraint system as a function of signals from the ARA controller and real-time occupant-restraint system interactions.

Abstract: A method and apparatus for detecting an improperly installed auxiliary child seat of the type that is secured in a motor vehicle by the seatbelt, and providing an alert to a vehicle operator in the case of improper installation. A seat occupancy sensor, a seatbelt buckle condition sensor, and a seatbelt tension sensor provides electrical signals to a child seat detection module, which determines that an improper installation condition exists if the auxiliary child seat is present and the seatbelt buckle is unfastened. The child seat detection module further determines an improper installation condition if the auxiliary child seat is present, the seatbelt buckle is fastened, and the seatbelt tautness is not within an acceptable range. If an improper installation condition is detected, the child seat detection module triggers an alerting device, such as a warning light on the instrument panel or audible chime.

Abstract: An airbag electrical control unit mounted in a vehicle includes a position detecting circuit that detects a current position of the vehicle; a computing circuit that computes impact that the vehicle undergoes using a signal from a sensor; and a notifying circuit that notifies a previously designated recipient of a notification data that includes the detected current information alone or both the detected current position and the computed impact. Here, a traveling mode that addresses a traveling-period trouble generated while the vehicle is traveling and a parking mode that addresses a parking-period trouble generated while the vehicle is being parked are switched into each other.

Abstract: A driving assistance system for regulating an operation of a vehicle in a discrete manner according to different ranges of risk potentials associated with the vehicle, such that different risk potentials in different ranges are conveyed to the driver in a different and discrete manner. The system includes a device for calculating a risk potential associated with the vehicle, and a data processor for regulating an operation of the vehicle, such as a reaction force applied to the acceleration pedal, based on a control parameter assuming one of a plurality of values according to the calculated risk potential associated with the vehicle, wherein each of the values is assigned to one of a plurality of predetermined ranges of risk potentials.

Abstract: A magnetic flux is sensed within a gap at a first location between two portions of a vehicle body/structure and a signal generated responsive thereto controls an element of the vehicle, wherein the magnetic flux is responsive to a disturbance of the vehicle body/structure. In one embodiment, the first location is proximate to the A-pillar, B-pillar or C-pillar. In another embodiment, at least a portion of the magnetic flux is generated by a coil at a different second location. A gap coil is located within a gap between portions of the vehicle body/structure for generating or sensing magnetic flux. A plurality of gap coils of various orientations provide for multi-axis sensitivity. In another aspect, a magnetic crash sensing system comprises a first coil at a first location, and a plurality of magnetic sensors at a plurality of corresponding second locations.

Abstract: A reconfigurable rollover event detection methodology utilizes an existing body of vehicle sensor data. A number of different algorithms or look-up modules develop rollover detection outputs based on different sets of sensor data, and a meta-algorithm combines the various rollover detection outputs to form a single rollover detection output. The number of individual rollover detection outputs is configurable depending on the extent of the available sensor data in a given vehicle and changes in sensor availability that occur due to sensor and communication failures.

Abstract: A method of determining a triggering decision for restraint devices in a vehicle, a triggering decision being determined as a function of a float angle, a vehicle sliding velocity and the vehicle tilt angle. The vehicle tilt angle is characterized here by a vehicle lateral acceleration and/or a vehicle sliding velocity. A passenger detection system may be used in addition.

Abstract: A method for determining the trigger time for restraint means in a vehicle is provided, where, by forming two time windows for the speed reduction in a crash, the slope of the speed reduction in the respective time windows and the position of the time windows are determined. In this manner, an exact determination of the trigger time in conjunction with a crash time and the crash speed may be achieved, which are ascertained with the aid of a pre-crash sensory system.

Abstract: A G sensor 31 generates a measuring value by measuring an impact acceleration applied to a vehicle. An A/D converter 32 converts the measuring value into a digital value with a resolution of K bits. A transmission interface 33 compresses the digital value into a compression digital signal of L bits being smaller than K bits. When the digital value is outside a given range from (2K?2L)/2 to (2K+2L)/2, the compression digital signal is generated by dividing the digital value by 2(K-L). When within the given range, the compression digital signal is generated without dividing the digital value. The compression digital signal corresponding to the digital value within the given range thereby maintains the resolution of K bits. Thus, even using the single G sensor, a resolution of a compression digital signal can be varied based on a low or high intensity level of G.

Abstract: An acceleration sensor module, installed in a front region and/or a side region of a vehicle, includes a sensing section and an adjusting section. The sensing section includes a capacitive detecting section and a converting section. The detecting section detects the acceleration of the vehicle. The converting section converts a capacitance value into a voltage value. The adjusting section includes an AD converter, a communication circuit, a power source section, and an oscillator. The AD converter converts an analog output of the converting section into a digital value. The communication circuit sends an output of the AD converter to a collision judging section. The power source section supplies electric power to each of the AD converter, the communication circuit, and the sensing section. The oscillator supplies the clock to the AD converter and to the converting section of the sensing section.

Abstract: A crash notification system (12) for an automotive vehicle (10) is used to communicate with a communication network (22) and ultimately to a response center (24). The system (12) within vehicle (10) includes an occupant sensor (30) that generates an occupant sensor status signal. A crash sensor (34) a vehicle identification number memory (48), or a vertical acceleration sensor (46) may also be used to provide information to the controller (14). The controller (14) generates a communication signal that corresponds to the occupant sensor status signal and the other information so that appropriate emergency personnel may be deployed.

Abstract: A vehicle occupancy sensing system provides a mechanism for determining whether a child is present in a vehicle. The sensing system may determine that an occupied front or rear facing child seat is present in an automobile, for example. To that end, the sensing system may employ a reliable electrode sensing system that may be conveniently installed in one or more locations in the vehicle seats. The sensing system thereby helps reduce occurrences of the potentially devastating consequences of unintentionally leaving a child in a vehicle.

Abstract: The purpose of this invention is to sense the presence of a seated occupant in a vehicle such as an automobile, plane, train or bus, or in a room or location where it is desirable to detect if seats are occupied. The occupant presence detection device consists of a single seat-mounted electrode, an oscillator circuit, a bridge circuit, a detection circuit and a circuit for processing the detected signals. The oscillator circuit excites the electrode. If an occupant is present on the seat, additional capacitance from the human body is introduced into the bridge via the electrode. This created differences in the voltage and phase of the waveform in each arm of the bridge circuit which are amplified by a differential amplifier. The signal is then converted to a DC voltage that, when above a predetermined threshold, causes the device to outputs a signal that indicates the presence of an occupant.

Abstract: The invention relates to a system for monitoring the interior of a vehicle, wherein changes occurring in the occupancy of a seat, e.g. with a person P, a child seat K, an empty seat L, or an occupancy in another occupancy category, are effected in a computer unit by means of transitional probabilities which are externally specified to the monitoring system and which reflect the rapid speed at which a change in occupancy is taken into account by said monitoring system. As a result, an associated airbag or another safety device is activated or de-activated accordingly.

Abstract: A method of discriminating the state of an object on a vehicle seat. The method includes taking samples of a signal indicative of seat load. It is provisionally determined that the object is in a second state if the seat load exceeds a first threshold, and it is provisionally determined that the object is in a first state if the seat load is less than a second threshold. It is determined that the object is in the first state if it is provisionally determined that the object is in the first state and if it is not provisionally determined that the object is in the second state. It is determined that the object is in the second state if it is provisionally determined that the object is in the second state and if it is not provisionally determined that the object is in the first state.

Abstract: A method for classifying an occupancy status of a vehicle seat includes associating a filtered class to a specific seat occupancy status based on a plurality of successive readings of at least one parameter value of a seat occupancy sensor, including the steps of: 1) determining an actual value of a first parameter of the seat sensor and associating an actual class to the actual value of the first parameter; 2) storing the actual class in a buffer, and deleting the oldest stored class; 3) plotting a confidence parameter indicative of the reliability of the actual class; 4) setting an updated filtered class to equal (i) an average of the classes stored in the buffer, if the confidence parameter is smaller than a first confidence threshold value, or (ii) the previously determined filter class, if the confidence parameter is greater than or equal to the first confidence threshold value.

Abstract: Vehicle telematics system including an occupant sensing system arranged to determine one or more properties or characteristics of occupancy of the vehicle, a crash sensor system for determining when the vehicle experiences a crash and a communications device arranged to enable a communications channel to be established between the vehicle and a remote facility after the vehicle is determined to have experienced a crash. Information determined by the occupant sensing system is transmitted via the communications channel to the remote facility, even in the absence of initiation of the communications channel by the occupant. The occupant sensing system may include an image-obtaining sensor for obtaining images of the passenger compartment of the vehicle, a motion sensor, receivers arranged to receive waves, energy or radiation from seating locations in the passenger compartment, heartbeat sensors, weight sensors associated with seats in the vehicle and/or chemical sensors.

Abstract: Method and apparatus for identifying and categorizing the weight and characteristics of the occupant currently occupying a vehicle seat. The method for identifying and categorizing the occupant or object involves measuring the deflection of the upper surface of the seat cushion at one or more points due to compression of the cushion produced by the weight distribution of the occupant. The system contains multiple sensor/emitter pairs for detecting the deflection. The system also includes a sensor to measure ambient temperature, preferably for temperature compensation due to the effects extreme temperatures may have on the compression properties of the seat cushion material and sensor/emitter pairs. A system processor interprets the data acquired by the sensors, and utilizes an algorithm and training tables to output a control signal indicative of the categorization of the occupant or object.

Abstract: An occupant of a motor vehicle seat is characterized for purposes of air bag suppression based on the seated weight of the occupant, the variation of the seated weight, and the occupant's apparent longitudinal center-of-mass. The method distinguishes between an adult and a child seat, distinguishes between forward-facing and rearward-facing child seats, and detects cinching of a child seat.

Abstract: A collision type identifying device is disposed in a central portion of a vehicle main body and has first deceleration detecting device (22), peak time detecting device (32), required time detecting device (34), and type identifying device (36). The deceleration detecting device (22) detects a vehicle deceleration in the longitudinal direction. The peak time detecting device (32) detects, as a first peak time (tp), a time from the excess of a preset threshold (GTH) by a waveform of the vehicle deceleration (G) detected by the deceleration detecting device (22) to a first peak. The required time detecting device (34) detects, as a required time (tn), a time when an integrated deceleration (VG) obtained through time quadrature of the vehicle deceleration (G) becomes equal to a predetermined integrated value set in advance. The type identifying device (36; 78) identifies a vehicle collision type on the basis of the first peak time (tp) and the required time (tn).

Abstract: Method and apparatus for identifying and categorizing the weight and characteristics of the occupant currently occupying a vehicle seat. The method for identifying and categorizing the occupant or object involves measuring the deflection of the upper surface of the seat cushion at several points and therefore the weight distribution of the occupant. The system contains multiple weight sensors arrayed for detecting the distribution of the load causing the seat deflection. The system also includes a sensor to measure ambient temperature, preferably for temperature compensation due to the effects extreme temperatures may have on the compression properties of the seat cushion material and the weight sensors. A system processor interprets the data acquired by the sensors, and utilizes an algorithm and weight tables to simulate a neural network in providing an output a control signal indicative of the categorization of the occupant or object.

Abstract: A method and system for determining weight and/or position of a vehicle seat occupant to be used for controlling the reaction of a safety restraint system. A plurality of spaced weight sensors are disposed between a seating surface and seat mounting surface to provide output signals indicative of an applied weight on each sensor. The sensors are spaced such that the sensors measure the weight applied to a seat back and the seating surface. A controller calculates the weight and/or position of the seat occupant in response to the output signals of the sensors. The controller sends the weight and position of the seat occupant to the safety restraint system to be used to tailor or suppress the reaction of the safety restraint system.

Abstract: A method is disclosed for managing variation in acceleration values obtained from a vehicle acceleration sensor for use in on-board computer based crash evaluation algorithm. Sources contributing to the variation are identified and a determination is made of the magnitude of the variation from each source to a selected multiple of a standard deviation, for example, 3 to 6 ?. The variation for each source is suitably combined to produce a database of acceleration-time history with the combined variations for use in calibrating and or validating a candidate crash algorithm.

Abstract: A method for adjusting a plurality of vehicle cockpit devices via a two-part process that utilizes device position constraints to determine candidate arrangements and then, ultimately, recommended arrangements of the vehicle cockpit devices to determine a desired setting of the various devices. The position constraints are determined using positioning data obtained from an occupant. An exploratory search routine is used to determine the candidate arrangements with the cockpit devices being moved to each candidate arrangement so that the occupant can be queried concerning the desirability of each such arrangement. The occupant's responses are then stored for later retrieval. Thereafter, a plurality of recommended arrangements of the cockpit devices are determined using a meta-heuristic pattern search along with a neural network search accelerator that permits screening of each recommended arrangement.

Abstract: A system for detecting wheel lift of an automotive vehicle has a speed sensor (22) coupled to a wheel (12) of automotive vehicle (10). A torque control system (20) is coupled to wheel (12) to change the torque at the wheel. A controller (18) is coupled to the torque control system and a speed sensor. The controller (18) determines lift by changing the torque of the wheel, measuring the change in torque and indicating lift in response to change in torque which may be indicated by wheel speed.