A Critical Analysis of Eight-Electromagnet Manipulation Systems: The Role of Electromagnet Configuration on Strength, Isotropy, and Access

It is known that in the creation of isotropic magnetic manipulation systems using a set of stationary electromagnets, eight electromagnets are necessary to ensure that there are no singularities in the workspace. A variety of eight-electromagnet configurations have been proposed to date. In the first contribution of this letter, we conduct a critical comparison of these proposed configurations, and find that certain configurations are superior in terms of field and torque generation, whereas others are superior in terms of force generation due to the spatial derivative of the field. All of the prior configurations comprise a high degree of symmetry, yet access to the workspace varies widely between designs. In the second contribution of this letter, we propose a new configuration that does not comprise the symmetry seen in prior systems, and also provides more open access to the manipulation workspace than prior systems, yet still exhibits an isotropic workspace with comparable performance to prior systems. We conclude that designers of isotropic eight-electromagnet manipulation systems should not feel obliged to incorporate symmetry into their design.