Longitudinal vehicle model
m·a = F_drive − F_brake − mg·sin(θ) − F_roll − F_dragDrive torque follows a broad diesel-like RPM curve. Tyre force is limited by a friction circle:
Fₓ² + Fᵧ² ≤ (μN)². Engine force is additionally power-limited at speed.
Suspension & stability
mₛ·ẍ + c·ẋ + k·x = F · undamped natural period
T = 2π√(m/k).
θ_tip = atan(b / h_CG) where
b is the remaining support half-span and
h_CG is the estimated combined centre-of-mass height. Payload shifts the first moment forward and upward; ballast shifts it rearward.
Assumptions & simplifications
Fixed integration step 1/120 s. Rigid chassis with scalar longitudinal speed; two-axle quarter-car suspension approximation; articulated steering represented as a yaw joint with lateral tyre-force demand. No terrain mesh collision solver, wheel-by-wheel contact patch, drivetrain gears, hydraulic fluid compressibility, bucket material granular simulation, or full 6-DOF rigid-body solver. Stability angle is a quasi-static geometric estimate, not a certified rollover prediction. Wet-mud μ values are illustrative.
Visible part hierarchy
root / chassisarticulation_yawrear_chassisfront_chassiscab / engine_coverfront_axle / rear_axlewheel_fl / wheel_frwheel_rl / wheel_rrlift_arm_left / rightbucket_hinge / bucketlift_arm_hinge · revolutebucket_hinge · revolutesuspension · prismaticwheel spin · revolute ×4
ASSETS · replacement manifest
| Part | Format | GLB URL |
|---|
| loader body | GLB | "" |
| industrial tyre | GLB | "" |
| bucket | GLB | "" |
| site hopper | GLB | "" |
Automated hook: window.__selfTest() runs closed-form slope, tip-angle and spring-period checks.