A low-cost method, which integrates distance sensing functionality into a switched\nelectromagnet by using a hybrid switching mode and current ripple measurements, is proposed.\nThe electromagnet is controlled by a micro-controller via a MOSFET H bridge, utilizing\na comparator-based current control. Additionally, a method for calculating the inductance of the\nelectromagnet and approximating the magnetic contact between the electromagnet and its target is\nalso presented. The resulting tool is attached to an industrial robot, and the system performance\nusing this setup is evaluated. Distance sensing in the range of 0mmto 5.2mm is demonstrated. It is\nalso shown that the relation between magnetic contact, coil current and calculated inductance can be\nreduced to a predictive look-up table, enabling the quality of the magnetic contact to be estimated\nusing minimal computational effort.
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