We discuss the first-ever experimental realization of the onboard excitable chemical controller for stimulus-guided navigation of mobile robots. We demonstrate that the Belousov–Zhabotinsky (BZ) reaction in the form of an onboard thin layer chemical reactor can be used to execute primitive forms of positive taxis. To dynamically shape the robot's motion trajectory in an experimental arena, we stimulate a marginal part of the BZ reactor with silver and analyse snapshots of the spatial excitation dynamics. In the paper, we offer an experimental set-up, including algorithms and interfacing, for an on-board chemical robotic controller, which contributes to the fields of non-classical computation, nonlinear physics, and unconventional robotics.