Abstract: A vehicle running condition judgment device for accurately detecting a change in a road surface condition and a vehicle's limit running condition. With substitution of respective tire characteristics and a detected state quantity into a vehicle motion model, vehicle slip angles are estimated for respective assumed road surface conditions. Based on the current state quantity and the last estimated vehicle slip angle, currently estimated vehicle slip angles for the respective assumed road surface conditions are compensated. A differential operation section calculates an estimation value of a vehicle slip angular velocity for each of the assumed road surface conditions based on the compensated vehicle slip angles for the respective assumed road surface conditions. Meanwhile, an operation section calculates a detection value of a vehicle slip angular velocity based on the detected state quantity.

Abstract: In a wheel condition estimating apparatus for estimating a wheel condition in a wheel resonance system including a frictional characteristic between a tire and a road surface, a transfer characteristic of the wheel resonance system from the vibration input to the output response is expressed by a transfer function including, as an unknown component of a wheel condition, a physical quantity relating to ease of a slipping between the tire and the road surface, an output response with respect to the vibration input to the wheel resonance system is detected and the unknown component which substantially satisfies the detected output response is estimated on the basis of the transfer function.

Abstract: An apparatus for diagnosing a fault in a dynamic system includes a controller which controls the dynamic system through use of a control input signal and vibrates the dynamic system through use of an vibration signal irrelevant to the internal state quantity of the dynamic system; an observer for estimating, on the basis of a response output from the vibration dynamic system, total disturbance which is a sum of an internal disturbance vector stemming from a fault in the dynamic system and a vibration disturbance vector occurring in the dynamic system through vibration; a correlation calculation unit which calculates cross-correlation between the thus-estimated total disturbance and the internal state quantity of the dynamic system and separates a component related to the internal disturbance from the total disturbance; and a diagnostic unit for diagnosing a fault in the dynamic system on the basis of the thus-separated component related to the internal disturbance.

Abstract: A wheel information estimating apparatus, which includes: a detecting device for detecting a wheel motion state relating to a movement of a tired wheel of a motor vehicle; an estimating device for estimating wheel information relating to the tired wheel, on the basis of the wheel motion state detected by the detecting device; and a modifying device for modifying an element relating to estimation of the wheel information, so as to improve an accuracy of estimating the wheel information. The element to be modified is selected from a movement of a center of rotation of the tired wheel as viewed in a plane in which the wheel is rotated, a signal applied from the detecting device to the estimating device, and an internal parameter used by the estimating means for estimating the wheel information.

Abstract: An anti-lock braking system includes a friction torque gradient estimating unit for estimating, from a small number of parameters, the gradient of friction torque with respect to a slip speed, and controls a braking force acting on wheels on the basis of the friction torque gradient estimated by the friction torque gradient estimating unit. The friction torque gradient estimating unit may employ several types of estimating methods; e.g.

Abstract: An apparatus and method for detecting friction characteristics are disclosed, in which a wheel resonant system includes a vehicle body, a road surface and at least a wheel. A braking force control system exerts a braking force on the wheel. A resonant component detector determines a resonant gain providing the ratio between the amplitude of predetermined frequency component of the braking force and that of the wheel velocity and detects the ratio of the resonant gain to a present reference gain, a deviation calculator calculates the deviation between this ratio and unity, a PI controller controls the braking force control system in such a manner that the deviation coincides with zero, and a friction characteristics detector detects the friction characteristics on the basis of the braking force. When the friction force is made to approach a peak value by increasing the braking force, the resonant characteristics undergo a change thereby to reduce the resonant gain.

Abstract: In a tire air pressure estimation based upon vibration components extracted rom a vehicle wheel speed signal, when the vehicle is a driven vehicle wheel, the precision of estimation is improved by canceling the components of vibration due to the resonance of the drive system from the vibration components based upon which the estimation calculation is made. The vibration components due to the resonance of the drive system can be canceled by canceling those vibration components extracted from the vehicle wheel speed signal which are the same in the phase between left and right driven vehicle wheels. When the tire air pressure of one of a pair of left and right driven vehicle wheels is lower than that of the other, the lower tire air pressure is more correctly estimated. Therefore, the higher tire air pressure may be estimated according to the lower tire air pressure against the drive system resonance.

Abstract: A driver regards a relative acceleration of a subject vehicle with respect to an object such as a preceding vehicle, an obstacle and the like as one having highest priority, and performs control such that deceleration is immediately started even if a relative velocity is small if the relative acceleration is large. Taking note of this point, the relative acceleration between the subject vehicle and the object is detected, and it is judged whether or not the subject vehicle and the object relatively approach each other at a relative acceleration not less than a predetermined value. A vehicle velocity is controlled such that the relative acceleration is not more than a predetermined target relative acceleration (for which a direction for approach is positive) when the subject vehicle and the object relatively approach each other at a relative acceleration not less than the predetermined value. Thus, the start of deceleration felt by the driver is adequate.

Abstract: A braking force acting on the wheel is actuated by a very small amount at a resonant frequency of a vibrating system comprised of a vehicle body, a wheel, and road surface, and the amplitude of the resonant-frequency component of the wheel speed is detected. A gain in the amplitude of the resonant-frequency component of the wheel speed with respect to the amplitude of the very small actuation of the braking force is determined. A mean braking force is controlled to decrease when the gain is smaller than a reference value, and to increase when the gain is greater than the reference value.

Abstract: The invention is a method and apparatus wherein a disturbance acting on a tired wheel of a vehicle is estimated by a disturbance observer on the basis of the detected angular velocity of the wheel. In one form of the method, the wheel angular velocity is compensated for the disturbance, depending upon the amount of change of the wheel angular velocity caused by the disturbance. In another form of the method, the angular acceleration of the wheel as well as the disturbance is estimated by the observer, and the moment of inertia of the wheel is obtained according to a relationship between the estimated disturbance and angular acceleration of the wheel.

Abstract: A diagnosing apparatus for diagnosing a dynamic system by detecting a fault of the dynamic system. The diagnosing apparatus comprises: disturbance estimating means for estimating an integrated disturbance vector, which is the sum of external and internal disturbance vectors of the dynamic system, based on an internal state vector of the dynamic system; correlation calculating means for calculating a cross-correlation between the estimated integrated disturbance vector and the internal state vector and for separating from the integrated disturbance a component relating to the internal disturbance; and diagnosing means for specifying a corresponding fault portion of the dynamic system from the separated component relating to the internal disturbance.

Abstract: A current component, in which a phase angle is different by a predetermined reference angle from a magnetic flux occurring in an inductive load, is brought to a q-axis current. The q-axis current is computed on the basis of phase current. A phase angle of the magnetic flux is detected. A q-axis-current control phase and a reference potential phase are determined on the basis of the result of pulse-width-modulation computation and the phase angle. The q-axis-current control phase is controlled in a pulse-width-modulation manner. A potential of the remaining reference potential phase if fixed to a reference potential. Thus, interference among the phases is prevented to reduce current ripple.

Abstract: An inverter controller for controlling an inverter having a plurality of electric valves each formed by connecting a switching element and a diode in anti-parallel with each other. On the basis of an output current command value, an ON/OFF signal is supplied to a switching element which needs to operate, and the supply of an ON signal to a switching element which need not operate is inhibited. Thus, it becomes unnecessary to provide dead time which has heretofore been needed.

Abstract: A method of controlling current of a multi-phase inverter is based on the principle that, when an appropriate switching mode is set, the direction of change of the position of the end of the current deviation vector must converge within a specific range which is determined in accordance with a presently output voltage vector. Accordingly, the direction of change of the position of the end of the current deviation vector and a presently set switching mode are detected during each control period to make a judgement as to whether or not the detected current deviation change direction belongs to a predetermined reference change direction range.

Abstract: An inverter current controlling method wherein output currents of an inverter having a plurality of switching elements and connected to a three-phase load are detected, and the switching elements are ON/OFF controlled so that the waveforms of the output currents are approximated to set output current wave commands, respectively, comprising: maintaining a specific switching element in a specific state so that a specific output terminal of the inverter is fixed to a specific polarity during a period of time when a specific ideal phase voltage of the three-phase load corresponding to the output current wave command is in a predetermined phase; and ON/OFF controlling the switching elements other than the specific switching element during the period of the predetermined phase so that the output current waveforms are approximated to the output current wave commands, respectively. Also disclosed is an inverter current controlling apparatus suitably employed in the above-mentioned method.

Abstract: Method and system of controlling an inverter are disclosed. A reference rotary magnetic flux as a desired magnetic flux of an AC motor is so determined as to make a uniform rotary motion, an actual magnetic flux of the AC motor is detected, voltage vectors are selected such that a deviation between this reference rotary magnetic flux and the magnetic flux of the AC motor may be a value held within a tolerance, and switching elements of the inverter are on-off controlled so that the voltage vectors thus selected can be obtained.

Abstract: The multi-level inverter according to the present invention comprises: a group of DC power supplies including three or more DC power supplies which are connected in series with same polarities, a group of terminals including a plurality of terminals for taking desired voltage levels from the opposite end and respective connecting points of group of DC power supplies, a group of switches consisting of switches having open modes and short-circuit modes equal in number to the terminals in the group of the terminals, with respective terminals on the input side being connected to the terminals in the group of terminals and respective terminals on the output side being commonly interconnected, and output terminals connected to the terminals on the output side being commonly interconnected in the group of switches. A contact of a switch connected to a terminal corresponding to desired voltage levels is closed to output voltages at multi-levels to be applied to a load.