Commercialization of CCEFP Research on Novel Magnetic Based Position Measurement System

Achievement date: 

Researchers with the NSF-funded Engineering Research Center (ERC) for Compact and Efficient Fluid Power (CCEFP), headquartered at the University of Minnesota, have shown that the magnetic field variation around a ferromagnetic object can be accurately modeled using only the geometry of the object under consideration. A patent has been filed and members of the CCEFP research team started a company, Innotronics LLC, to license and commercialize this technology, with an industrial member partner of the ERC sponsoring additional research demonstrations of the technology on their system.


Ferromagnetic objects have inherent magnetic fields around them. CCEFP’s modeling of the inherent magnetic field makes it possible to measure the position of any ferromagnetic object accurately without direct conduct.The magnetic-based position measurement system is applicable to accurate position measurement of both small and large ferromagnetic objects, including cars on highways, oscillating pistons in integrated circuit (IC) engines, pneumatic cylinders, hydraulic cylinders, as well as moving parts in many machines.


The CCEFP magnetic-based position measurement system relies only on a small, inexpensive magnetic sensor. With the use of one additional redundant magnetic sensor, the need to calibrate the position measurement system can be further eliminated.

The CCEFP model was motivated by the Center’s work developing a Free Piston Engine Pump (FPEP). One of the critical barriers to overcome was the need to quickly and accurately measure the position of the outer piston in a potentially harsh operating environment. The non-contacting magnetic sensor solved this difficult problem, as the FPEP was equipped with a redundant linear variable differential transformer (LVDT), which was used only as a reference sensor. Modeling the inherent magnetic field of the outer piston and measuring the field using magnetic sensors successfully estimated piston position. These results demonstrate that the developed technology is capable of accurately estimating piston position even under fast transients. In cases where the piston does not have an inherent magnetic field (for example, pistons made of aluminum), the same technology can be applied by adding a magnet to the piston head. This has been shown through experiments with a pneumatic actuator made of aluminum; in these experiments, an LVDT was again used as a reference.

Innotronics LLC has obtained two funding awards from the inventing university, an NSF Partnerships for Innovation (PFI) Accelerating Innovation Research (AIR) Technology Transfer (TT) award from NSF, and a sponsored-research contract from an industry member to further demonstrate the technology on their system.