Internally-balanced magnet unit

In order to construct a robot capable of walking around and working on walls and ceilings of buildings and large structures, it is essential, as a prior condition, to produce a highly reliable sticking device which will enable the robot to hold securely on vertical and under-surfaces. This paper discusses a magnetic sticking unit for a robot moving on steel sheets often used in large structures such as ships and atomic power generators, etc. Firstly, existing magnetic sticking units are sudied for comparison and a newly conceived concept of "Internally-Balanced Magnet" is proposed. The Internally-Balanced (abbreviated IB) Magnet comprises of a permanent magnet which generates a strong sticking force, together with a spring unit which cancels the internal force so that the robot hands/feet are provided with easy sticking and releasing actions. The paper further presents the design process for the magnetic sticking unit necessary for assembling the IB magnet and the nonlinear spring unit to counter-balance the magnet unit. Finally, the validity of this system as a sticking unit for a mobile robot is demonstrated by experimental walks of a man wearing the IB magnet system on his hands and feet on steel walls and ceilings.