Dynamic 3D Motion Tracking, 85-Inch-Range Position Transducer

Position Measurement & Control - Issue 39

PRODUCT FOCUS 1

RoundAbout™ Cable Guide Gives Dynamic 3D Motion Following

Patented Design Solves a Range of Motion-Following Problems

Figure A1 - The RoundAbout™ cable guide allows 3D tracking of applications while providing one dimension of feedback.

The RoundAbout™ cable guide is a simple yet elegantly-designed cable-directing device that allows SpaceAge Control cable-actuated position transducers to follow motion dynamically in 3D space. The product uses two precision-positioned pulleys that provide two dimensions of the tracking capability. The third dimension of tracking capability is provided by a bearing-mount housing incorporating a cable-actuated rotation mechanism (a cable interface surface). The product eliminates the need for specific pulleys to be mounted to provide 2D and 3D motion tracking and gives dynamic tracking capability. The product eliminates requirements for flexible mounting bases or re-location of the position transducer.

Figure A2 - Applications that move in 3D space can now be tracked using the RoundAbout™ cable guide.

The product has significance to design and test personnel who need to incorporate flexible displacement measurement sensors into applications. The product allows tracking of one-dimension of motion in 3D space. Three or four position transducers with the RoundAbout™ cable guide can be used to create a local, medium-accuracy coordinate measurement machine. The product functionality can be viewed in this animated GIF file.

Similar designs do not allow for dynamic motion nor for full 3D range of motion, a limitation induced in most cases by the use of a single pulley. Some similar designs rely on the cable moving over non-rotating surfaces resulting in friction and wear that reduce the unit's lifetime and accuracy. The RoundAbout™ cable guide incorporates a 2nd pulley, a housing mounted on a precision bearing, and a cable-interface curve on the housing the rotates the housing dynamically to the correct orientation. These design attributes give the product unsurpassed flexibility to track 3D motion with cable-type actuation.

To learn more about the product, view the RoundAbout™ cable guide data sheet. The RoundAbout™ cable guide is offered on the Series 160/161/162 and Series 6 product lines.

PRODUCT FOCUS 2

Model 62-60 Position Transducer: Rugged, 85-Inches (2159 mm)

Medium-Range Entry Sets Standard for Position Transducer Repeatability

Doubling the maximum range of the Series 6 product line, the Model 62-60 position transducer family is now shipping. With a maximum range of 85 inches (2159 mm), the Model 62-60 family provides all the benefits of the Series 6 product line including:

1. Choice of 5 FlexSignal™ and Digital Output Signals (Factory Set)
2. AccuTrak™ Threaded Drum For Enhanced Repeatability
3. DirectConnect™ Sensor-To-Drum Technology = Zero Backlash, No Torsion Springs or Clutches
4. NEMA 4 / IP 66 Environmental Protection
5. Flexible Mounting Bases
6. Industrial Operating Temperature Ranges
7. Choice of Electrical Terminations: MIL-C-5015, DIN 45326, Lemo, flying leads

Figure B1 - The Model 62-60 position transducer shown with the RoundAbout™ cable guide installed.

Visit the Series 6 data sheet to learn more about the Model 62-60.

DESIGN TOOL

Determine Voltage Conditioner Flexibility: Zero-Span Calculator

Three Calculators in One for Pre- and Post-Purchase Inquiries

Need proof of exactly how flexible the SpaceAge Control voltage conditioner is? If so, visit the Zero-Span Calculator that allows you to set the parameters of interest for your application to determine the output possibilities of the voltage conditioner.

The Zero-Span Calculator provides:

• zero control
• min and max voltage span
• min and max sensitivity
• max range for a given power supply
• min power for given desired output
• singled-ended and differential min and max value examples

Figure C1 - The voltage conditioner block diagram

APPLICATION CORNER

Q. Many of your data sheets with voltage divider-type electrical outputs show a specification for "Output Smoothness". What is output smoothness?

A. Per VRCI-P-100A, output smoothness is a measurement of any spurious variation in the electrical output not present in the input. It is expressed as a percentage of the total applied voltage and measured for specified travel increments over the theoretical electrical travel. Output smoothness includes effects of contact resistance variations, resolution, and other micro-nonlinearities in the output.

The "noise" test performed on wirewound potentiometers measures ENR (Equivalent noise resistance) which is a variation in real or apparent contact resistance in the wiper circuit. This measurement is significant for potentiometers used in rheostat applications, but not for potentiometers used as voltage dividers in which very little, if any, current flows in the wiper circuit. For voltage divider applications, the output smoothness test is used, which reflects sudden variations in output of voltage dividers. If the potentiometer is used with a finite load, the effect of contact resistance variation is included in the output smoothness test along with all other causes of noise in the output signal.

Performing output smoothness testing requires a specific output smoothness filter and specialized motion control equipment. To review the test procedure, visit section 6.2 of VCRI-P-100A (pdf file - Industry Standard - Precision Potentiometers).

Figure D1 - Output smoothness trace per VRCI-P-100A.

ISSN 1527-5108 • Document Number S050Y(041215)