Augmented and virtual reality applications must track the locations near the user’s hands, head, or other control devices. There are a number of ways to monitor these motions, but one of the most dependable is with electromagnetic motion tracking. The sensors employ 3D cube geometries with three individual coils oriented in the X, Y, and Z axes.
When developing these coils, it is vital to remember that today, applications need more precision than ever, and the speed of growth in this very competitive market requires fast product development.
The AR/VR software which converts the information from the sensors into virtual movement needs predictable, accurate data from all of the coils. Roshan Shrestha, TT Electronics Design Engineer, says that product developers usually specify the size constraints, inductance (L), and direct current resistance (DCR) for every coil, leaving the actual coil design to the engineers.
Before manufacturing begins, the engineers at TT Electronics design and create prototypes using production materials for the developer’s evaluation testing. The challenge is selecting from the complete range of coil variables – winding angle, core material, number of turns, wire gauge, etc. – that permit the software and sensor to best meet the product developer’s needs.
Until now, this was an error-prone, labor-intensive process of hand calculation and trial-and-error testing. It was iterative and time consuming, and only worked because tolerances were typically looser than todays. TT Electronics utilizes powerful ANSYS Maxwell field simulation software for the analysis of electromagnetic devices in order to achieve today’s tighter tolerances.
A design engineer in Maxwell produces a 3D model of the cube (winding and core). The engineer defines crucial coil input variable information like excitation to the coils and material characteristics, and then begins the simulation to confirm if the coil parameters are within spec and predict performance.
Virtual prototypes which meet those requirements are produced by the 3D simulation software. Depending on the complexity of the design, results are available in minutes or hours. The virtual prototypes include all of the winding characteristics and material of an actual physical prototype and can be immediately tested in a simulated field without having to create a physical coil.
Using 3D printing, a physical sample can be created for fast evaluation in the lab. A number of designs may be tested before building the first physical prototype in some cases. The process is much quicker and more accurate than manual calculation and permits easy testing of factors like winding angle to acquire the perfect fit for the application.
Scott Cameron, Business Development Manager, says that the physical prototype is tested by both TT Electronics and its customer. The customer usually tests the coil in prototype circuitry for the final product, which in some cases can result in alterations to the coil specifications by the application developers. However, in most instances, the amount of changes required to create a suitable coil is slashed along with cost and time to market.
The ANSYS Maxwell software and 3D printing are just one of the tools TT Electronics employ to create electromagnetic products that live up to the name.