Switchable Magnets as a Power-Efficient Alternative for Electromagnets in a Mobile Robotic System

The goal of this research is to investigate the power-efficiency of a switchable magnet, in place of an electromagnet, to pick up one-inch diameter ferromagnetic coins for a color coin sorting mobile robot. Recently, switchable magnets have been proven to be more energy efficient than an electromagnet in mobile robotic applications. This is because electromagnets require a constant state of power consumption where switchable magnets only require power to change its state on or off. Switchable magnets are used just like electromagnets for magnetic flux control to induce magnetic attraction to an object by changing its state. The switchable magnet's housing is fitted with a digital servo motor to rotate the top dynamic magnet 180° using pulse width modulated signals to change its state to on or off. A switchable magnet and electromagnet are tested for their respective power consumption on the mobile systems battery pack by measuring the current and voltage over the time that it takes to pick up and drop off a single coin. The results show that the switchable magnet uses 59.8% less power, measured in Watts, while being able to hold 5 times more weight, measured in Newtons, than the electromagnet. Over the duration of 20 seconds, the time estimated to displace the coin, the switchable magnet will use 25 times less power, measured in milliAmp-hours, compared to the electromagnet; therefore, switchable magnets present a more power-efficient alternative for magnetically controlled applications, specifically on a mobile system.