Patent ID: 6601011
Filing Date: 2003-07-29
Classification: G01P

Abstract:
An apparatus for measuring an angular velocity variation rate of a rotary axle, comprising:an approximately circular disc shaped plate attached approximately concentrically around the rotary axle, the approximately circular disc shaped plate including a plurality of approximately equally spaced apart projections on a circumference thereof; a first pair of velocity pulse generators, each velocity pulse generator of the first pair being disposed around the circumference of the plate on a first virtual line passing through a center of the rotary axle with one of the velocity pulse generators positioned in an 180Â° revolution difference with respect to the other and generating a corresponding one of first and second velocity pulse signals in synchronization with a revolution of the plate; a first couple of angular velocity measuring sections that measure an angular velocity of the rotary axle from the corresponding one of first and second velocity pulse signals outputted by the first pair of the velocity pulse generators and outputs first and second angular velocity indicative signals each one indicating the measured angular velocity of the rotary axle independently of the other; a first average angular velocity measuring section that calculates an average value of the first and second angular velocity indicative signals outputted by the first couple of angular velocity measuring sections and outputs a first averaged angular velocity indicative signal indicating the average value of the first and second angular velocity indicative signals; a second pair of velocity pulse generators, each velocity pulse generator of the second pair being disposed around the circumference of the plate on a second virtual line passing through the center of the rotary axle and being inclined with respect to the first virtual line at an angle of 180Â°/m, wherein m denotes a number of times per revolution of the rotary axle that a variation of an angular velocity variation rate indicative signal occurs, and being set when the variation in the angular velocity variation rate indicative signal occurs m-the number of times per revolution of the rotary axle, and generating a corresponding one of third and fourth velocity pulse signals in synchronization with the revolution of the plate; a second couple of angular velocity measuring sections that measure the angular velocity of the rotary axle from the corresponding one of third and fourth velocity pulse signals outputted by the second pair of the velocity pulse generators and output third and fourth angular velocity indicative signals each one indicating the measured angular velocity of the rotary axle independently of the other; a second average angular velocity measuring section that calculates an average value of the third and fourth angular velocity indicative signals outputted by the second couple of angular velocity measuring sections and outputs a second averaged angular velocity indicative signal indicating the average value of the third and fourth angular velocity indicative signals; and a differentiating section that differentiates a signal based on at least one of the first and second averaged angular velocity indicative signals outputted by the first and second average angular velocity measuring sections to output the angular velocity variation rate indicative signal.