PURPOSE: To accurately decide an adverse road and to improve riding sensation, by deciding that a road is adverse when frequency, wherein the speed component of a suspension exceeds a reference level, exceeds a given frequency.
CONSTITUTION: A displacement sensor FR is located to the pistong rod of a piston cylinder mechanism 10 of a suspension on the front right side, and a displacement sensor FL is situated to a suspension on the front left side. An adverse road deciding circuit 60 includes a differentiation circuit 70A for differentiating a displacement signal from the sensor FR, an absolute value 80A, a subtractor 90A, comparator 100A, an F/V converter 110A, a differentiation circuit 79B for differentiating a displacement signal from the sensor FL, an absolute circuit 80B, a subtractor 90B, a comparator 100B, an F/B converter 120, and a hold circuit 130. A signal is converted into an analogue signal by a converter, the signal is compared with a second reference value V2 by a comparator, where it is detected whether frequency wherein the speed component of the suspension exceeds a specified amplitude value exceeds given frequency V2.
SHIMA NAOTO
KITSUKAWA YUKIMI
