ABSTRACT
A technology that has the potential to do proximity sensing and—to some degree—object classification is capacitive sensing. The chapter presents that capacitive sensing can be a part of the solution to the problem stated in the beginning. It introduces capacitive sensing and some applications where capacitive sensing is already used within a safety system. It emphasizes the difficulties that arise when in this context. It also presents State-of-the-art measurement circuitry concepts for capacitive sensing and analyses with respect to safety applications. The chapter presents a new approach founded on the concept of electrical capacitance tomography (ECT), and also presents an evaluation measurement circuitry. Capacitive sensing is well described by the Maxwell equations. In order to assess advantages and disadvantages of possible circuitry for capacitive sensing, a model of the sensor front end is necessary. Possible calibration techniques and the available frequency hopping of the excitation signal will allow to handle parasitic effects and improve capacitive sensing for safety applications.
