Extremum seeking with very slow or drifting sensors

Slow sensors arise in many applications, including sensing of concentrations of chemicals in tracking of contaminant plumes. Slow sensors are often the cause of poor performance and a potential cause of instability. In this paper we design a modified extremum seeking scheme to account for and even to exploit slow sensor dynamics. We also consider the worst case, which is sensor dynamics governed by a pure integrator. We provide stability results for several distinct variations on our ES scheme. We use metal-oxide microhotplate gas sensors as a real world example of slow sensor dynamics, model the sensor based on experimental data, and provide extremum seeking simulation results employing the identified sensor model.