STICK-SLIP DETECTION METHOD AND APPARATUS

In a stick-slip detection method, the displacement of a movable member having a slidable contact portion is detected. A first quantity of state is calculated on the basis of the detected displacement of the movable member. A second quantity of state, which can be estimated from the first quantity of state, is calculated on the basis of the detected displacement of the movable member. An estimated quantity of state is calculated by estimating a second quantity of state from the calculated first quantity of state by using the relationship between the first and second predetermined quantities of state which are obtained from the displacement of the movable member in a normal sliding state. The calculated second quantity of state is compared with the estimated quantity of state to determine an abnormal sliding operation of the movable member on the basis of the comparison result. A stick-slip detection apparatus is also disclosed.