94 lines
1.8 KiB
Odin
94 lines
1.8 KiB
Odin
// https://www.edy.es/dev/docs/pacejka-94-parameters-explained-a-comprehensive-guide/
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package physics
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import "core:math"
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Pacejka94_Longitudinal_Params :: [14]f32
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Pacejka94_Lateral_Params :: [18]f32
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PACEJKA94_LONGITUDINAL_PEAK_X :: 6.24
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PACEJKA94_LONGITUDINAL_PARAMS :: Pacejka94_Longitudinal_Params {
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1.5,
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0,
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1100,
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0,
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300,
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0,
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0,
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0,
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-2,
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0,
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0,
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0,
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0,
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0,
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}
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PACEJKA94_LATERAL_PEAK_X :: 6.26
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PACEJKA94_LATERAL_PARAMS :: Pacejka94_Lateral_Params {
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1.4,
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0,
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1100,
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1100,
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10,
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0,
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0,
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-2,
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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0,
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}
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// X is slip ratio percentage [-100, 100] or slip angle in degrees, where positive angle is turning left
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// Output is the friction coefficient
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pacejka_94_longitudinal :: proc(
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b: Pacejka94_Longitudinal_Params,
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x: f32,
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f_z: f32,
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s_v: f32 = 0,
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) -> f32 {
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f_z_sq := f_z * f_z
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C := b[0]
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D := (b[1] * f_z + b[2]) * f_z
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BCD := (b[3] * f_z_sq + b[4] * f_z) * math.exp(-b[5] * f_z)
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B := BCD / (C * D)
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H := b[9] * f_z + b[10]
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E := (b[6] * f_z_sq + b[7] * f_z + b[8]) * (1.0 - b[13] * math.sign(x + H))
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V := b[11] * f_z + b[12]
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Bx1 := B * (x + H)
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F := D * math.sin(C * math.atan(Bx1 - E * (Bx1 - math.atan(Bx1)))) + V
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return F / (f_z * 1000)
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}
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pacejka_94_lateral :: proc(
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a: Pacejka94_Lateral_Params,
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slip_angle: f32,
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f_z: f32,
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camber_angle: f32,
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) -> f32 {
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camber_angle_sq := camber_angle * camber_angle
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C := a[0]
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D := f_z * (a[1] * f_z + a[2]) * (1.0 - a[15] * camber_angle_sq)
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BCD := a[3] * math.sin(math.atan(f_z / a[4]) * 2.0) * (1.0 - a[5] * abs(camber_angle))
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B := BCD / (C * D)
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H := a[8] * f_z + a[9] + a[10] * camber_angle
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E := (a[6] * f_z + a[7]) * (1.0 - (a[16] * camber_angle + a[17]) * math.sign(slip_angle + H))
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V := a[11] * f_z + a[12] + (a[13] * f_z + a[14]) * camber_angle * f_z
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Bx1 := B * (slip_angle + H)
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F := D * math.sin(C * math.atan(Bx1 - E * (Bx1 - math.atan(Bx1)))) + V
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return F / (f_z * 1000)
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}
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