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A Phase-Changing Pendulum to Control Spherical Robots and Buoy Sensors

The pendulum adds new flexibility to motion control. NASA’s Jet Propulsion Laboratory, Pasadena, California A novel mechanical control system has been proposed for spherical robots to be used as multifunctioning sensor buoys in areas with ambient forces such as winds or currents. The phase-changing pendulum has been specifically designed for Moballs, a self-powered and controllable multifunctioning spherical sensor buoy to be used in the Arctic and Antarctica, or in other solar system planets or moons with atmosphere, such as Mars or Titan. The phase-changing pendulum has been designed to function in different phases: 1) When used as the spherical buoy, the Moball needs to take advantage of external forces such as the wind for its mobility. With no constraints, it could keep the center of mass in the geometric center of the sphere to facilitate the sphere’s movement. 2) However, as soon as the Moball needs to slow down or stop, the sphere’s center of mass can be lowered. 3) Furthermore, the phase-changing pendulum could lean to the sides, thereby changing the direction of the Moball by biasing its center of mass to the corresponding side. The Moballs could take advantage of such a novel phase-changing pendulum to go as fast as possible using the ambient winds, and to stop or steer away when facing hazardous objects or areas (such as the gullies), or when they need to stop in an area of interest in order to perform extensive tests. It is believed that this is the very first time that a pendulum has been suggested to control a spherical structure where both the length and the angle of the pendulum are adjustable in order to control the sphere. 4) Finally, the phase-changing pendulum could also control the sphere in the absence of wind. The spherical sensor buoys or Moballs could use the stored harvested energy (e.g., from sunlight or earlier wind-driven motions) to move the phase-changing pendulum and create torque, and make the spherical sensor buoys initiate rolling with the desired speed and direction. This is especially useful when the spheres need to get close to an object of interest in order to examine it.

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Linear Position Sensors

H. G. Schaevitz Alliance Sensors Group (Moorestown, NJ) introduced the LR-19 series inductive linear position sensors. The contactless devices are designed for factory automation and a variety of industrial or commercial applications such as motor sport vehicles, automotive testing, solar cell positioners, wind turbine prop pitch and brake position, and packaging equipment. They are offered in six full-scale ranges from 25 to 200 mm. Operating from a variety of DC voltages, the sensors offer a choice of four analog outputs and include proprietary SenSetTM field recalibration.

Posted in: Articles, Products, Positioning Equipment, Sensors

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Stepper Motor

Lin Engineering (Morgan Hill, CA) released the Xtreme Torque E5618 stepper motor that has been designed to reduce stalling, skipped steps, and provide efficient torque. The new design allows users to stay within the same frame size. The NEMA 23 stepper has a holding torque of 150 oz-in and is suited for applications with heavier loads or at increased risk of stalling or skipping steps. It also allows for an integral connector or flying lead wires.

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Motor Driver ICs

Toshiba America Electronic Components (San Jose, CA) offers four motor driver ICs, ranging from precision stepper motor drivers to sensorless brushless DC motor drivers. The TB67S269FTG bipolar stepping motor driver has a maximum rating of 50V and 2.0A. Three brushless DC motor drivers — the TB67B001FTG, TB67B008FTG, and TB67B008FNG — feature maximum rating of 25V and 3.0A. The TB67S269FTG targets applications requiring high-speed, high-precision motor drives. The driver’s high-resolution, 1/32-step motor driving technology lowers noise and vibration, while heat generation is reduced via low ON resistance (0.8Ω or less, upper + lower) MOSFET H-bridges and featuring Toshiba’s Advanced Mixed Decay (ADMD) technology that optimizes the drive capability of complex motor currents.

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Encoders

CUI (Tualatin, OR) offers the AMT31 modular encoder series that generates standard U/V/W commutation signals for vectoring current to brushless motors. Positional information is generated using a patented capacitive code generation system coupled with a proprietary ASIC. The encoder is designed for use in brushless dc motor applications subject to vibration and contaminants such as dust, dirt, and oil that typically stop optical encoders from working effectively. They deliver accuracy of ±12 arcmin (±0.2 mechanical degrees). Twenty programmable resolutions are available with a range of 48 to 4096 PPR.

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AC Drive

The VACON® 100 FLOW from VACON (Milwaukee, WI) is an AC drive designed to improve flow control for multi-pump applications in which several pumps are used in place of a single one. The drive offers control of flow and pressure for a maximum of eight pumps (or fans) without the need for an external controller — communication between drives is provided by integrated RS-485. It is equipped with built-in Ethernet as standard, eliminating additional options or gateways needed to communicate with process automation. The drive offers three multi-pump control solutions: single-drive multi-pump, multi-drive multi-master, and multi-drive multi-follower.

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Table Motors

Siemens AG (Munich, Germany) offers the Simotics DP motors based on the 1LE1 motor platform. The ventilated roller table motors are designed for applications in the steel industry where they must meet requirements for vibration and shock according to Class 3M4. Versions of the motors are optimized for use with converters of the Sinamics S120 series and, as integrated drive systems, contribute to reliable and efficient operation. The motor design has been tested in accordance with to DIN EN60721-3-3. They are available in 4- and 6-pole designs with shaft heights from 112 to 280 mm, and in the torque range from 20 to 578 Nm. The series comprises not only mains powered motors, but also versions optimized for converter operation with special insulation systems. When used together with the Sinamics S120 drive system, these motors form an integrated drive system.

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