This standard specifies criterion threshold and evaluation of controllability and stability for automobiles.
This standard is applicable to the automobiles running on highways or urban roads. Off-highway automobiles may make reference to this standard.
2 Steady State Circular Test
2.1 This test is scored upon evaluation on such three indexes as lateral acceleration at neutral turning point, an, degree of understeer, U, and side tilt of trunk, Kφ.
2.2 For lower limit values of an, U and Kφ as an60, U60 and Kφ60 and upper limit values as an100, U100 and Kφ100, see Table 1.
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2.3 The lateral acceleration at the neutral turning point, an, is defined as the lateral acceleration at a point where the gradient is zero on the relation curve of front/rear axle slip angle difference versus lateral acceleration. Within the range of the tested lateral acceleration, in the absence of neutral turning point, an value is estimated by the least square method as the cubic polynomial fitting curve without constant term.
