I am a research student and am working on vehicle modelling in matlab/simulink. Currently am studying behavior of standing car that how it settles it roll pitch and yaw angle.
While doing so i encountered a problem that how we would deal with longitudinal and slip velocities at low speed that are approaching zero.
longitudinal slip= (r*w- vx)./|vx| lateral slip= -arctan(vy./vx)
Should i ignore the velocities upto some value and let slip be zero. As tire forces are proportional to slip and when i include them the model becomes unstable. and specially the ratio becomes high.
I am stuck in this problem for months please help i found this forum really helpful.