Wirtgen has introduced a new "Auto-Centre" steering assist feature for its W 210i and W 220i large cold milling machines. When rehabilitating urban roads, the milling machine often follows a "trenching" operation where a specific lane or strip of asphalt is removed. If the machine drifts even slightly, the milling drum can strike a manhole frame, a concrete curb, or a water valve box, causing catastrophic damage to the drum cutting tools and the road infrastructure.
The Auto-Centre system utilizes two ultrasonic sensors mounted on the front and rear of the machine chassis. These sensors measure the distance to the edge of the previous cut (the vertical asphalt face). The system creates a "virtual wall" relative to the existing edge. If the operator's manual steering input causes the machine to drift towards this wall, the system automatically overrides the steering hydraulic valves to correct the path.
Crucially, the system features an "Obstacle Recognition" logic. It is pre-programmed with the GPS coordinates of known underground utilities. As the machine approaches a manhole frame, the system automatically raises the milling drum by 2 cm to skim over the steel casting, protecting the cutting bits from impact. The operator can adjust the sensitivity of the steering intervention via the armrest console. This automation significantly reduces the cognitive load on the operator, who previously had to constantly correct the steering to match the edge line, allowing them to focus on depth control and engine load management.
