Overview - ISO 11012:2009 (weave test, transition test)
ISO 11012:2009 specifies two open‑loop vehicle dynamics test methods for quantifying on‑centre handling of heavy commercial vehicles and buses: the weave test and the transition test. These methods measure vehicle response to controlled steering inputs while the vehicle is driven nominally straight at a constant speed. ISO 11012:2009 applies to heavy trucks, trailers and buses as defined in ISO 3833 (vehicle categories M3, N2, N3, O3, O4).
Key topics and technical requirements
- Test purpose: quantify on‑centre handling - the steering feel and precision at low lateral acceleration (typically ≤ 1 m/s²).
- Test types:
- Weave test: sinusoidal (standard) or other oscillatory steering input (standard frequency 0.2 Hz) to examine the vehicle response at the outer edge of the hysteretic region.
- Transition test: ramp steering inputs to examine the transition from straight‑line driving into the hysteretic region.
- Measured variables (first vehicle unit): steering‑wheel angle and torque, yaw rate, longitudinal velocity, lateral acceleration; steering‑wheel angular velocity recommended.
- Reference system: intermediate axis of first vehicle unit; reference point located at the first axle wheel centre (overrides ISO 15037‑2).
- Test conditions:
- Standard speed: 80 km/h (other speeds permitted; ±2 km/h target tolerance).
- Track dimensions: weave ≈ 1 000 m × 20 m; transition needs less length but ≈ 40 m width.
- Wind limits: ambient wind ≤ 5 m/s, ideally ≤ 1.5 m/s; avoid gusting > 1.5 m/s.
- Minimum of repeated cycles: at least four consistent cycles (weave) and five repeats (transition).
- Measuring equipment: per ISO 15037‑2. Typical operating ranges / recommended maximum errors (examples from standard):
- Steering‑wheel angle ±80° (±0.5° error)
- Steering torque ±10 Nm (±0.1 Nm)
- Yaw rate ±10°/s (±0.1°/s)
- Lateral acceleration ±5 m/s² (±0.05 m/s²)
- Data output: time histories, hysteresis loops, characteristic values derived for analysis.
Applications and users
ISO 11012:2009 is used by:
- Vehicle and chassis manufacturers for steering and handling development
- Test engineers and proving ground teams validating on‑centre behavior
- Research institutions studying vehicle dynamics
- OEM suppliers (steering systems, suspension, tyres) assessing component influence on handling
Practical uses include design validation, comparative handling assessments, and development of steering controls and stability systems. Note: ISO 11012 quantifies a specific part of vehicle behaviour; results should be combined with other tests for comprehensive handling evaluation.
Related standards
- ISO 15037‑2 - general conditions for heavy vehicle dynamics tests
- ISO 3833 - vehicle type definitions
- ISO 8855 - vehicle dynamics vocabulary
Keywords: ISO 11012:2009, heavy commercial vehicles, buses, weave test, transition test, on‑centre handling, vehicle dynamics, open‑loop test methods, steering input.