Method of preventing skid of wheels of a vehicle

An anti-skid method of preventing skid of the wheels of a vehicle comprising:

• detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle, setting a reference wheel-speed signal (U.sub.R) from the detected vehicle speed for comparison with said wheel-speed signal (Uwi), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said wheel-speed signal (Uwi) with said reference wheel-speed signal (U.sub.R) and also said wheel-acceleration signal (Uwi) with said reference wheel-deceleration signal (-Vwo), controlling a braking torque (T.sub.B) applied to said wheel such that torque is maintained constant when the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U.sub.R) and simultaneously the level of said wheel-acceleration signal (Uwi) is lower than that of said reference wheel-deceleration signal (-Vwo);
• and further comprising the steps of reducing the brake torque when the level of the wheel-speed signal is lower than that of the reference wheel-speed signal and simultaneously when the level of the wheel-acceleration signal is lower than that of the reference wheel-deceleration signal.

An anti-skid method of preventing skid of the wheels of a vehicle comprising:

• detecting the peripheral speed of a wheel of a vehicle and picking it up as a wheel-speed signal (Uwi), detecting the speed of the vehicle and picking it up as a vehicle-speed signal (U), determining a reference wheel-speed signal (U.sub.R) based on said vehicle-speed signal (U) for comparison with said wheel-speed signal (Uwi), setting a low reference vehicle-speed signal (Uo) for comparison with said vehicle-speed signal (U), deriving a wheel-acceleration signal (Uwi) from said wheel-speed signal (Uwi), setting a reference wheel-deceleration signal (-Vwo) representative of a negative wheel-acceleration for comparison with said wheel-acceleration signal (Uwi), comparing, during braking, said vehicle-speed signal (U), said wheel-speed signal (Uwi) and said wheel-acceleration signal (Uwi) with said low reference vehicle-speed signal (Uo), said reference wheel-speed signal (U.sub.R) and said reference wheel-deceleration signal (-Vwo), respectively, and controlling a brake torque (T.sub.B) applied to said wheel such that as long as the level of said vehicle-speed signal (U) is greater than that of said low reference vehicle-speed signal (Uo), said brake torque (T.sub.B) is maintained constant from the instant when the level of said wheel-acceleration signal (Uwi) falls below the level of said reference wheel-deceleration signal (-Vwo) if the level of said wheel-speed signal (Uwi) is higher than that of said reference wheel-speed signal (U.sub.R), and thereafter, said brake torque (T.sub.B) is reduced from the instant when the level of said wheel-speed signal (Uwi) falls below that of said reference wheel-speed signal (U.sub.R) if the level of said wheel-acceleration signal (Uwi) remains below the level of said reference wheel-deceleration signal (-Vwo), and said brake torque (T.sub.B) is permitted to increase freely at the instant when the level of said vehicle-speed signal (U) is decreased below the level of said low reference vehicle-speed signal (Uo).