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Software helps create a more efficient washing machine

Researchers at German switch manufacturer Marquardt Gmb used Maple technical-computing software from Maplesoft, Waterloo, Ont., to design a 3-D Hall sensor application-specific integrated circuit (ASIC) for washing machines that helps boost their efficiency. The Hall-sensor module is part of the housing, while the magnet is attached to the drum. As the machine washes a load, the sensor measures the direction and strength of the magnetic field to determine the relative movement of the magnet in all three dimensions. The information goes to the onboard microcontroller, which uses a proprietary algorithm that speeds or slows drum rotation to compensate for load imbalances. This lets the machine run more smoothly and consume less power.

Researchers say Maple software helped them model magnetic fields, estimate tolerances for the magnet, and determine whether the tilt of the 3-D-Hall-Sensor module was within an acceptable tolerance of approximately 2°. The software then translated the resulting positioning algorithm into C code which then ran on the controller.

“It is simple to work in Maple, even with complex and symbolic mathematics,” says Marquardt group leader Frank Allmendinger. “Interoperability with different technical programs is good, and the software has export capabilities to other languages such as C, Java, and Matlab.”

According to Allmendinger, using mathematic field modeling makes it possible to discard traditional 3D mapping and use a smaller, less expensive microcontroller. Also, it takes fewer resources to create the smaller magnet.

The company may extend the sensor capability so it can determine the distance and orientation of a Hall sensor from a magnet. To solve the problem, it will be necessary to measure the magnetic field at two positions. This involves solving a six-dimensional system of equations, also possible in Maple, says Allmendinger.

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