Robust Active Noise Reduction in Off-Highway Machines Using Remote Quiet Zones
* Presenting author
Abstract:
In recent years, the technology of active noise control (ANC) has found its way into various applications and thereby evolved to a well-known feature by now, e.g., in headphones or cars. While rather targeting comfort in these examples, it is also a potential solution to reduce noise exposure in terms of occupational safety. Particularly, operators of off-highway machines are exposed to the permanent machine-related noise. The probability of a hearing loss in their profession is 60 %. This contribution presents an active noise cancelling system to reduce the noise level inside the cabin of off-highway vehicles, without requiring headphones or other devices to be carried along. Being designed as an active headrest, it consists of two loudspeakers mounted to the headrest of the operator’s seat, which emit the sound to interfere destructively with the noise at the operator’s ears. To create the resulting quiet zones at those very points, a dual-channel feedforward design is combined with virtual sensing, consequently expanding the frequency bandwidth and thus the perceivable noise reduction. Due to uncertainties in the control environment, incorporating virtual sensing in practice is a challenging task, though. Hence, particularly solutions for a robust control approach are being investigated.