I. Introduction
In recent, the source location problem is a topic of great significance and has been widely concerned by researchers. This problem originates in many scenarios, such as automatic navigation, fire spot discover, disaster zone rescue, information detection, chemical spill investigation, hazardous gas forecast, and environment monitoring [1]–[9]. Among them, the sources can be generated by the diffusion or propagation of certain substances and fields, including plume odor, oil leakage, electromagnetic radiation, thermal processes, sound signals, and so on. It is worth mentioning that those sources may be in a dangerous environment or pose a risk to humans, thus search tasks for them are often accomplished by robots.