local FrictionPreset = class('FrictionPreset') function FrictionPreset:initialize(config) config = config or {} self.B = config.B or 10.86 self.C = config.C or 2.15 self.D = config.D or 0.933 self.E = config.E or 0.992 end function FrictionPreset:evaluate(slip) local t = math.abs(slip) return self.D * math.sin(self.C * math.atan(self.B * t - self.E * (self.B * t - math.atan(self.B * t)))) end return FrictionPreset