Diesel particulate filters (DPF) have seen widespread application in the United States and Europe to meet stringent diesel particulate matter (PM) emissions regulations. Now commonplace on most on-road diesel vehicles, DPFs are being increasingly applied to diesel-powered off-road equipment as additional regulations are phased in. Further, recent awareness of particulate matter emissions from gasoline direct injection engines has motivated additional study into potential applications of gasoline particulate filters (GPF).

Key to the efficient operation of the combined engine and emissions aftertreatment system, is the accurate determination of the filter loading state, to enable precise control of filter regeneration and on-board diagnostics. Currently pressure- and model-based controls are utilized, in parallel, to provide an indirect estimate of filter loading. This work presents results of an investigation applying radio frequencies (RF) to monitor the accumulation of particulate matter in the DPF, providing a direct, in-situ determination of filter loading state. Simulation results, supported by experimental measurements, are provided to demonstrate the utility of the technique to monitor not only the filter loading state but also to provide a measure of the spatial distribution of the accumulated material. The results of this work indicate significant potential to apply RF-based sensing for improved monitoring and control of the particulate filter in a range of applications.

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