Innovators at NASA Johnson Space Center have developed a method for controlling precise motion of a brushless DC (BLDC) motor using relatively inexpensive components. Precision motors are usually quite expensive and inefficient when operating at slow speeds. Current motors are only capable of operating at approximately 15 rpm with a risk of excessive jitters. The new technology uses a method to control BLDC motors over a broad range of speeds, ranging from about 0.025 rpm to about 7000 rpm.
The Precision Low-Speed Motor Controller was designed as part of an OpTIIX telescope for the International Space Station.
This technology is based on a precise current control loop and a high-fidelity velocity measurement algorithm. The precise current loop uses a mathematical model of the electrical dynamics of the motor, custom electronics, and a PI controller to maintain a rapid response and smooth current control. The velocity measurement algorithm is embedded in the velocity loop that is wrapped around the current loop to provide smooth, low-velocity control.
Commercial motors may employ this technology to extend their dynamic range. This technology can also be integrated into surgical robots that require advanced precision motion control systems. Hybrid and electric vehicles can integrate this technology into their operating system to improve efficiencies.
This technology's capability has been integral to the success of several NASA projects, such as the OpTIIX telescope, the NASA Robonaut 2 robot, and the Modular Robotic Vehicle (MRV).