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Electric Machine With Boosted Inductance to Stabilize Current Control

High-powered motors typically have very low resistance and inductance (R and L) in their windings. This makes the pulse-width modulated (PWM) control of the current very difficult, especially when the bus voltage (V) is high. These R and L values are dictated by the motor size, torque (Kt), and back-emf (Kb) constants. These constants are in turn set by the voltage and the actuation torque-speed requirements. This problem is often addressed by placing inductive chokes within the controller. This approach is undesirable in that space is taken and heat is added to the controller.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Positive-Buoyancy Rover for Under Ice Mobility

This floating rover operates at the ice/water interface in lakes and seas. A buoyant rover has been developed to traverse the underside of ice-covered lakes and seas. The rover operates at the ice/water interface and permits direct observation and measurement of processes affecting freeze- over and thaw events in lake and marine environments. Operating along the 2- D ice-water interface simplifies many aspects of underwater exploration, especially when compared to submersibles, which have difficulty in station-keeping and precision mobility.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs, TSP

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International Space Station- Based Electromagnetic Launcher for Space Science Payloads

A method was developed of lowering the cost of planetary exploration missions by using an electromagnetic propulsion/launcher, rather than a chemical-fueled rocket for propulsion. An electromagnetic launcher (EML) based at the International Space Station (ISS) would be used to launch small science payloads to the Moon and near Earth asteroids (NEAs) for the science and exploration missions. An ISS-based electromagnetic launcher could also inject science payloads into orbits around the Earth and perhaps to Mars.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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High-Precision Encoders for GEO Space Applications

These encoders are designed for precision pointing in high-duty-cycle applications. High-precision encoders are used by earth observation instruments and in mechanisms for laser communication terminals (LCTs). A micro-radian resolution encoder for the LCT was designed for precision pointing applications, especially in geosynchronous Earth orbit (GEO) environments with a 15-year lifetime, and in high-duty-cycle applications.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Magnetostrictive Alternator

This innovation replaces the linear alternator presently used in Stirling engines with a continuous-gradient, impedance-matched, oscillating magnetostrictive transducer that eliminates all moving parts via compression, maintains high efficiency, costs less to manufacture, reduces mass, and eliminates the need for a bearing system.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs, TSP

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A Kinematic Calibration Process for Flight Robotic Arms

The Mars Science Laboratory (MSL) robotic arm is ten times more massive than any Mars robotic arm before it, yet with similar accuracy and repeatability positioning requirements. In order to assess and validate these requirements, a higher-fidelity model and calibration processes were needed.

Posted in: Mechanics, Mechanical Components, Machinery & Automation, Briefs

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Working With Mechanical Motion Subsystems

Embedded motion subsystems are engineered to fit within a predefined physical space on a machine and tie into the machine's motion control system, ready to accept commands from a top-level computer interface, control card or PLC. This plug-and-play approach to motion can increase the performance while reducing development time and cost. Read more about these embedded mechanical systems in our latest technical paper.

Posted in: Machinery & Automation, White Papers

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