# Magic Formula: Calculating of lateral forces

To obtain lateral force according to slip angles, I use Pacejka Magic Formula, but my graph's style is not similar with picture which i added. I cannot find where the mistake is.

clear all
clc
a1y=-22.1;
a2y=1011;
a3y=1078;
a4y=1.82;
a5y=0.208;
a6y=0.00;
a7y=-0.354;
a8y=0.707;
Fz=2;
Sh=-0.28;
Sv=-118;
Cy=1.5;
Dy=a1y*Fz^2+a2y*Fz;
BCDy=a3y*sind(a4y*atand(a5y*Fz));
By=BCDy/(Cy*Dy);
Ey=a6y*Fz^2+a7y*Fz+a8y;
alpha_r=-10:0.01:10;
plot(alpha_r,PCKy)  • could you reference the paper where you got the coefficients and the graph? I've done enough work on Pacejka, to know that different people approach it differently Dec 11, 2020 at 9:11
• I use Wong - Theory of Ground Vehicles. I cannot add pages of the book because of copyright :)
– voo
Dec 11, 2020 at 9:12
• It would help if you also detailed chapter and maybe even page. Dec 11, 2020 at 9:13
• Pages 60-63 contain my problem
– voo
Dec 11, 2020 at 9:14

PCKy=(Dy*sind(Cy*atand(By*rad2deg(alpha_r+Sh) - Ey*(By*rad2deg(alpha_r+Sh) - atand(By*rad2deg(alpha_r+Sh))))))+Sv;
PCKy=(Dy*sind(Cy*atand(By*(alpha_r+Sh) - Ey*(By*(alpha_r+Sh) - atand(By*(alpha_r+Sh))))))+Sv; 