Control apparatus for internal combustion engine

A control apparatus for an internal combustion engine, the control apparatus comprising:

• an electronic control unit configured to:
• (i) acquire a rotational speed signal correlated with a detected rotational speed of the internal combustion engine having n cylinders, where n is larger than two,
• (ii) extract, from the acquired rotational speed signal, at least first-order and lower-order than the first-order components of the rotational speed signal, where one cycle is defined as one combustion cycle of the internal combustion engine,
• (iii) extract, from the acquired rotational speed signal, at least an n-th-order component of the rotational speed signal, where one cycle is defined as one combustion cycle of the internal combustion engine,
• (iv) determine that no disturbance has occurred in the rotational speed of the internal combustion engine when a first-order parameter regarding a magnitude of an amplitude of the extracted first-order and lower-order than the first-order components is smaller than a first threshold,
• (v) determine that a disturbance has occurred in the rotational speed of the internal combustion engine when the first-order parameter is equal to or larger than the first threshold and an n-th-order parameter regarding an amplitude of the extracted n-th-order component is equal to or larger than a second threshold, and
• (vi) in response to determining that no disturbance has occurred in the rotational speed of the internal combustion engine, control an operation state of the internal combustion engine based on at least outputs from a plurality of sensors, and in response to determining that the disturbance has occurred in the rotational speed of the internal combustion engine, do not control the operation state of the internal combustion engine.