Abstract: A control system for a plant, having an identifier and a controller. The identifier identifies model parameters of a controlled object model which is obtained by modeling the plant. The controller calculates a control input to the plant so that an output from the plant coincides with a control target value, using the identified model parameters. The controller calculates a self-tuning control input, using the model parameters identified by the identifier. The controller further calculates a damping control input according to the rate of change in the output from the plant or the rate of change in a deviation between the output from the plant and the control target value. The controller calculates the control input to the plant as a sum of the self-tuning control input and the damping control input.

Abstract: A control system for a plant is disclosed. According to this system, a model parameter vector of a controlled object model which is obtained by modeling the plant, is identified. A controller controls the plant using the identified model parameter vector. An identifying error of the model parameter vector is calculated, and an updating vector is calculated according to the identifying error. The updating vector has at least one first element which is relevant to an input or an output of the plant, and a second element which is irrelevant to the input and the output of the plant. The updating vector is corrected by multiplying a past value of at least one first element of the updating vector by a predetermined value which is greater than “0” and less than “1”, and multiplying a past value of the second element of the updating vector by “1”. The model parameter vector is calculated by adding the corrected updating vector to a reference vector of the model parameter vector.

Abstract: The temperature of an exhaust gas flowing through an exhaust passage 3 is estimated or detected, and the temperature of an active element of an exhaust gas sensor 8. (O2 sensor) is controlled at a predetermined target temperature by a heater using the estimated or detected temperature of the exhaust gas. For estimating the temperature of the exhaust gas in the vicinity of the exhaust gas sensor 8, the exhaust passage 3 extending up to the exhaust gas sensor 8 is divided into a plurality of partial exhaust passageways 3a through 3d, the temperatures of the exhaust gas in the partial exhaust passageways 3a through 3d are estimated successively from an exhaust port 2 of an engine 1. The temperature of the exhaust gas is estimated according to an algorithm which takes into account a heat transfer between the exhaust gas and passage-defining members 6a, 6b, 7 which define the exhaust passage 3 and a heat radiation from the passage-defining members into the atmosphere.

Abstract: A control system for a throttle valve actuating device is disclosed. The throttle valve actuating device includes a throttle valve of an internal combustion engine and an actuator for actuating the throttle valve. A control object model is defined by modeling the throttle valve actuating device. The throttle valve actuating device is controlled based on a controlled object model so that an opening of said throttle valve coincides with a target opening.

Abstract: An apparatus controls the temperature of an exhaust gas sensor disposed in an exhaust passage of an internal combustion engine. An exhaust gas temperature estimating unit sequentially estimates the temperature of exhaust gas flowing through the exhaust passage, using at least a parameter representative of an operating state of the internal combustion engine. A heater control unit controls a heater for heating an active element of the exhaust gas sensor to a predetermined target temperature, using an estimated value of the exhaust gas from the exhaust gas temperature estimating unit.

Abstract: The present invention provides a controller for controlling a modeled plant robustly against disturbance. The controller comprises an estimator and a control unit. The estimator estimates disturbance applied to the plant. The control unit determines an input to the plant so that an output of the plant converges to a desired value. The input to the plant is determined to include a value obtained by multiplying the estimated disturbance by a predetermined gain. Since estimated disturbance is reflected in the input to the plant, control having robustness against disturbance is implemented. The controller may comprise a state predictor. The state predictor predicts the output of the plant based on the estimated disturbance and dead time included in the plant. The control unit determined the input to the plant so that the predicted output converges to a desired value. Since the state predictor allows for the dead time, the accuracy of the control is improved.

Abstract: A state determining apparatus for an exhaust gas purifier is provided for accurately determining the state of the exhaust gas purifier including an adsorbent for adsorbing hydrocarbons, including a deterioration of the adsorbent, in accordance with an ignition time of an internal combustion engine. The state determining apparatus for an exhaust gas purifier is arranged in an exhaust system of the internal combustion engine for determining the state of the exhaust gas purifier including the adsorbent capable of adsorbing hydrocarbons and moisture in exhaust gas. The state determining apparatus has a humidity sensor arranged at a location downstream of the adsorbent in the exhaust system for detecting the humidity of exhaust gases, and an ECU for determining the state of the adsorbent in accordance with the humidity of exhaust gases detected by the humidity sensor, and the ignition time of the internal combustion engine.

Abstract: A control system for a plant is disclosed. According to this system, a value of a switching function which is defined as a linear function of a deviation between the output of the plant and a control target value, is calculated. A reaching mode input is calculated. The reaching mode input contributes to placing a deviation state quantity which is defined based on the deviation, onto a switching straight line on which the value of the switching function becomes zero. The reaching mode input is corrected according to the value of the switching function. A control input to the plant is calculated with a response specifying type control, and the control input includes the reaching mode input. The plant is controlled with the calculated control input.

Abstract: A system controls the air-fuel ratio in an exhaust gas supplied from an internal combustion engine to a catalytic converter in order to keep an output voltage Vout of an O2 sensor disposed downstream of the catalytic converter at a predetermined target value Vop. In the system, the temperature of an active element of the O2 sensor is controlled at a predetermined temperature such that the output voltage of the O2 sensor at an inflection point of output characteristics thereof is substantially the same as the target value Vop.

Abstract: A control system for a plant, having an identifier and a controller. The identifier identifies model parameters of a controlled object model which is obtained by modeling the plant. The controller calculates a control input to the plant so that an output from the plant coincides with a control target value, using the identified model parameters. The controller calculates a self-tuning control input, using the model parameters identified by the identifier. The controller further calculates a damping control input according to the rate of change in the output from the plant or the rate of change in a deviation between the output from the plant and the control target value. The controller calculates the control input to the plant as a sum of the self-tuning control input and the damping control input.

Abstract: The present invention provides a control apparatus for a plant, which can suppress excessive correction for a spiky disturbance being applied and maintain a good controllability, when controlling the plant, which is a controlled object, with the self-tuning regulator. A detected equivalent ratio KACT is input to a high-pass filter 33, and a high-pass filter output KACTHP is input to a parameter adjusting mechanism 42. The parameter adjusting mechanism 42 calculates a corrected updating vector (KID·d&thgr;(k)) by multiplying an updating component d&thgr; of a model parameter vector by a correction coefficient KID, and adds the corrected updating vector to a preceding value &thgr;(k−1) of the model parameter vector, to thereby calculate a present value &thgr;(k). The correction coefficient KID is changed from “1.0” to a value near “0” upon detection of the spiky response where an absolute value of the high-pass filter output KACTHP increases.

Abstract: The present invention provides a control system for an internal combustion engine for detecting a torque variation based on a rotational speed of the engine and suppress the torque variation. The system includes a detector for detecting a rotational speed of the engine, a memory for storing a variation pattern of the rotational speed of the engine when a torque of the internal combustion engine is excessive and a controller for calculating a variation component of the rotational speed based on the detected rotational speed, The controller calculates the correlation between the variation component and the variation pattern that is read out from the memory and then determines a torque variation state of the engine based on the correlation.

Abstract: A catalyst state detector for detecting a state of an exhaust gas purifying catalyst which is capable of accurately detecting the state, including deterioration, of an HC adsorbent contained in the exhaust gas purifying catalyst for adsorbing hydrocarbons in exhaust gases of an internal combustion engine, and can be manufactured at a low cost. The exhaust gas purifying catalyst is arranged at an intermediate portion of an exhaust pipe, and the HC adsorbent is capable of adsorbing hydrocarbons and moisture in exhaust gases. The catalyst state detector comprises a downstream humidity sensor arranged at a location downstream of the HC adsorbent in the exhaust pipe for detecting a humidity of the exhaust gases, and an adsorbent state detecting unit (ECU) for detecting the state of the HC adsorbent in accordance with the result of detection made by the downstream humidity sensor.

Abstract: A temperature estimating apparatus for an internal combustion engine is provided for correctly calculating the temperature of an exhaust device even when the internal combustion engine is started under low temperature conditions. The temperature estimating apparatus comprises an ECU for estimating the temperature of a hydrocarbon adsorbent in an exhaust system of the internal combustion engine through calculations. The ECU calculates an estimated adsorbent temperature of the adsorbent in accordance with an engine rotational speed, an absolute intake pipe inner pressure, an engine water temperature, an intake temperature, and a detected humidity of exhaust gases. This calculation is started when condensation, which has occurred within an intake pipe, is eliminated.

Abstract: A state determining apparatus for an exhaust gas purifier is provided for determining the state of the exhaust gas purifier including an adsorbent for adsorbing hydrocarbons; in accordance with the temperature state in the exhaust system of an internal combustion engine. The state determining apparatus is arranged in an exhaust system of the internal combustion engine. The state determining apparatus comprises a humidity sensor for detecting the humidity within a bypass exhaust pipe, and an ECU for determining the temperature state of the exhaust system and determining the state of adsorbent in accordance with the humidity within the bypass exhaust pipe detected by the humidity sensor and the temperature state in the exhaust system detected by the ECU.

Abstract: An exhaust emission control system for an internal combustion engine having an exhaust system is disclosed. The control system may include an exhaust gas purifying device provided in the exhaust system and an oxygen concentration sensor provided downstream of the exhaust gas purifying device. The exhaust gas purifying device may include at least an oxygen storing ability or a nitrogen oxide storing ability. An air-fuel ratio of an air-fuel mixture supplied to the engine may be enriched with respect to the stoichiometric air-fuel ratio, so as to reduce the oxygen or nitrogen oxides stored in the exhaust gas purifying device. A predicted value of the output from the oxygen concentration sensor may be calculated using a predictor based on the fuzzy logic reasoning. The completion of the reduction of the oxygen or nitrogen oxides stored in said exhaust gas purifying device may be determined according to the predicted value.

Abstract: A control system for a plant is disclosed. The control system includes a controller for controlling the plant based on a controlled object model which is obtained by modeling the plant. The controlled object model is modeled using an input and an output of the plant which are sampled at intervals of a sampling period which is longer than a control period of the controller. The sampled input of the plant is a filtered control output which is obtained by filtering an output of the controller. The controller carries out a control process of the plant at intervals of the control period.

Abstract: A target air-fuel ratio KCMD for an exhaust gas upstream of a catalytic converter is sequentially determined to converge the output VO2/OUT of an O2 sensor downstream of the catalytic converter to a target value VO2/TARGET, and the amount of fuel supplied to an internal combustion engine is controlled to converge the output KACT of an air-fuel ratio sensor to the target air-fuel ratio KCMD. While the amount of fuel supplied to the internal combustion engine is being thus controlled, the value of a deterioration linear function &sgr; whose variable components are represented by time-series data of the output VO2/OUT of the O2 sensor is determined. A central value of the square &sgr;2 of the value of the deterioration linear function &sgr; is determined as a deterioration evaluating parameter. A deteriorated state of the catalytic converter is evaluated on the basis of the value of the deterioration evaluating parameter.

Abstract: A vehicle controller for controlling the air-fuel ratio of an engine is provided. In one embodiment, the controller comprises a first exhaust gas sensor provided downstream of the catalyst for detecting oxygen concentration of exhaust gas, a first decimation filter connected to the first exhaust gas sensor, and a control unit connected to the first decimation filter. The control unit determines a manipulated variable for manipulating the air-fuel ratio. The first decimation filter oversamples, low-pass filters and then downsamples the output of the first exhaust gas sensor. The first decimation filter can remove chemical noise from the output of the exhaust gas sensor. In another embodiment, a second decimation filter is connected to a second exhaust gas sensor provided upstream of the catalyst for detecting the air-fuel ratio of the exhaust gas. The second decimation filter overasmples, low-pass filters and then downsamples the output of the second exhaust gas sensor.

Abstract: A control system for an internal combustion engine having an exhaust system, an intake system, and an exhaust gas recirculation mechanism for recirculating exhaust gases from the exhaust system to the intake system is disclosed. The exhaust system is provided with an adsorbent for adsorbing hydrocarbon. When the adsorbent has adsorbed the hydrocarbon and the engine is operating in an idling condition, an intake air amount of the engine is increased and an ignition timing of said engine is retarded, and at the same time, the exhaust gas recirculation is performed to recirculate the hydrocarbon desorbed from the adsorbent to the intake system.