Internally-Balanced Magnetic Mechanisms Using a Magnetic Spring for Producing a Large Amplified Clamping Force

Abstract

To detach a permanent magnet using a control force much smaller than its original attractive force, the internally-balanced magnetic unit (IB Magnet) was invented. It has been applied to magnetic devices such as wall-climbing robots, ceiling-dangling drones, and modular swarm robots. In contrast to its significant reduction rate with regard to the control force, the IB Magnet has two major problems in its nonlinear spring, which serves the purpose of cancelling out the internal force on the magnet. These problems include the complicated design procedure and the trade-off relationship between balancing the precision and the volume of the mechanism. This paper proposes a principle for a new balancing method for the IB Magnet. This method uses a like-pole pair of magnets as a magnetic spring, whose repulsive force should equal the attractive force of an unlike-pole pair. To verify the proposed principle, a prototype of the IB Magnet was designed using a magnetic spring and verified through experiments such that its reduction rate is comparable to those of conventional IB Magnets. Moreover, a robotic clamp was developed as an application example that contains the proposed IB Magnets as its internal mechanism.