Motion Control

How To Substantially Reduce Encoder Cost While Gaining Functionality With Multi-Turn Rotary Position Sensors

Many applications require rotation counters that can measure angles greater than 360º. However the low-cost 10-turn potentiometers most design engineers are familiar with can’t always meet user requirements for resolution and reliability. As an alternative, optical absolute encoders are too expensive for many applications. These solutions require a continuous power supply or they will lose count when power is restored. Also, geared technology/rotation counters are subject to significant wear.

Posted in: White Papers, Motion Control, Automation, Robotics, Data Acquisition, Sensors
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Mechanisms for Achieving Non-Sinusoidal Waveforms on Stirling Engines

The current state-of-the-art Stirling engines use sinusoidal piston and displacer motion to drive the thermodynamic cycle and produce power. Research performed at NASA Glenn has shown that non-sinusoidal waveforms have the potential to increase Stirling engine power density, and could possibly be used to tailor engine performance to the needs of a specific application. However, the state-of-the-art Stirling engine design uses gas springs or planar springs that are very nearly linear, resulting in a system that resonates at a single frequency. This means that imposing non-sinusoidal waveforms, consisting of multiple frequencies, requires large forces from the drive mechanism (either the alternator or the crank shaft). These large forces increase losses, and increase the size and requirements of the control system. This innovation aims to reduce the external forcing requirements by introducing internal mechanical components that provide the forces necessary to achieve the desired waveforms.

Posted in: Briefs, Mechanical Components, Mechanics, Motion Control, Alternators, Alternators, Crankshafts, Engine efficiency, Stirling engines
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Improving Stirling Engine Performance Through Optimized Piston and Displacer Motion

Stirling engines typically achieve high efficiency, but lack power density. Low power density prevents them from being used in many applications where internal combustion engines are viable competitors, and increases system costs in applications that require Stirling engines. This limits their operating envelope in both terrestrial and space applications. Sinusoidal piston and displacer motion is one of the causes of low power density. Previous work proposed solving this problem by replacing sinusoidal waveforms with waveforms that more closely approximate those of the ideal Stirling cycle. However, when working with real engines, imposing ideal waveforms has been shown to reduce power density and efficiency due to increased pressure drop through the regenerator and heat exchangers.

Posted in: Briefs, Fluid Handling, Mechanical Components, Mechanics, Motors & Drives, Engine efficiency, Pistons, Stirling engines
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Prototype Capture System Simulates Asteroid Mission

A robotic capture module system prototype was built to help NASA engineers understand the operations required to collect a multi-ton boulder from an asteroid’s surface. The hardware includes three space frame legs with foot pads, and two seven-degrees-of-freedom arms with microspine gripper “hands” to grasp onto the boulder.

Posted in: News, Motion Control, Robotics
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Dike Inspection Robot is Energy-Autonomous

Inspecting the condition of dikes and other sea defense structures is typically a task for robots, working in a team and in a highly autonomous way. But if they move around across the dikes, perform tests, and communicate the results for six hours a day, they use a lot of energy.

Posted in: News, Motion Control, Motors & Drives, Power Transmission
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System Harvests Energy from Automotive Shock Absorbers

Boosting the fuel efficiency of motor vehicles by “harvesting” the energy generated by their shock absorbers and feeding it back into batteries or electrical systems such as air conditioning has become a major goal in automotive engineering. A University of Huddersfield (UK) researcher has designed a new system and built a prototype that is ready for real-world testing.

Posted in: News, Energy Harvesting, Motion Control
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Pedal Position Sensing in Heavy-Duty Vehicles

Pedal position detection is nothing new when it comes to operation of heavy duty equipment. However, the age old system operation of mechanical linkages between the pedal and the engine just might be coming to an end. New sensor technology is now enabling non-contact, drive-by-wire that can reduce total system cost while standing up to the harsh environments of off highway equipment.

Posted in: White Papers, Fluid Handling, Mechanical Components, Motion Control, Data Acquisition, Sensors
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Choosing Stepper- or Servo-Driven Actuators to Replace Air Cylinders

Pneumatic (air) cylinders are widely used in industrial automation due to their low per-axis cost and high-speed/force capabilities. They have a long history of being popular workhorses in the automation industry. However, there are many reasons to use electric actuators in place of air cylinders: reduced machine downtime, reduced energy consumption, increased precision, and increased speed. In addition, electric actuators can be powered by servo or stepper motors, in conjunction with a control device, to provide linear motion.

Advantages of Electric Linear Actuators

Reduced downtime. Electric linear actuators (whether screw- or belt-driven) are very low-maintenance. Regreasing may be the only regular maintenance necessary, and many screw-driven models are lubricated for the life of the actuator.

Posted in: Articles, Aerospace, Motion Control, Sensors and actuators, Sensors and actuators, Electric motors, Durability, Durability
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Custom Machines Create Engine Lip Skins on Boeing Aircraft

MJC Engineering, a custom machine tool builder in Huntington Beach, CA, specializes in metal-spinning machines for such applications as sheet spinning, flow forming, wheel spinning, and rotary forging. The company was commissioned to build a series of metal-spinning machines for GKN for use at its plants in Camarillo, CA and Orangeburg, SC. These machines produce lip skins for the engine housings on Boeing 777X and 737MAX aircraft. Using CNC from Siemens Industry (Elk Grove Village, IL) and robotic handling technology — in addition to its proprietary servopump-controlled Green Power™ hydraulic power unit that saves up to 40% on energy — the MJC team devised a unique solution to an engineering challenge brought to them by GKN.

Posted in: Application Briefs, Aviation, Motion Control, CAD / CAM / CAE, CAD, CAM, and CAE, Forming, Manufacturing equipment and machinery, Robotics, Commercial aircraft
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Linear Motor

The LinX® linear motor from Anca Motion USA (Wixom, MI) delivers a continuous force from 333 N to 665 N, and peak force from 2136 N to 4272 N. It features a cylindrical design with a thermal barrier that helps separate and remove heat from the motor. The motor’s zero net attractive forces eliminate the downforce associated with flatbed motors. Its cylindrical profile makes the system compact, effectively fitting into a space similar to that required by a regular ball-screw and circular motor. The motors are fully sealed and rated to IP67 or optional IP69K, making them well suited for machine tool and food processing systems. The motor can be enabled with an algorithm that increases axis stiffness and helps to minimize axis deflection with greater accuracy.

Posted in: Products, Motors & Drives
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