Longitudinal dynamics
m·dv/dt = F_drive − F_brake − F_roll − ½ρCdA·v|v| − mg·sin(θ)
Tyre grip (friction circle)
F_long,max = √[(μN)² − F_lat²]. Traction is Coulomb-limited by the remaining grip.
Suspension
m_s·z¨ + c·z˙ + k·z = k·r(x); the yard profile is a deterministic two-frequency approximation.
Tip-over estimate
θ_tip = atan(b / h_CG), where b = 0.69 m. Live tilt adds a simplified lateral-acceleration term.
Braking overlay
d_stop = v² / (2μg) for level ground, constant friction and zero brake delay.
Assumptions: planar rigid chassis; no tyre relaxation, driveline backlash, load-cell compliance, hydraulic pressure limits or 3D rollover. Steering/yaw and load sway are reduced-order approximations. The rain event changes effective μ; it is not a fluid simulation. Use this as an educational sandbox, not a certified forklift safety tool.