Ultrasound test systems manufacturer gets LG Motion treatment

15 February 2010

LG Motion works closely with world leading ultrasound test systems manufacturer Precision Acoustics – with the flexibility to supply customised positioning systems rapidly and competitively

Dorchester based Precision Acoustics Ltd is a world leading leading consultancy for acoustic measurement and a designer and manufacturer of transducers, hydrophones, acoustic materials and measurement equipment for ultrasound applications in healthcare, non destructive testing. Also, a major player in ultrasound research, the Company has close working relationships with major acoustics measurement systems manufacturers as well as world-wide academic
establishments including the acoustics group at the National Physical Laboratory.

As part of its ultrasound quality assurance service, Precision Acoustics has developed and manufactures the USM2 range of automated test tank scanning systems used for the verification and standards calibration of ultrasound components. With LabView® based software and all instrumentation included, these systems provide complete solutions for the repetitive tasks of data acquisition, information display, storage and the computation necessary for the measurement and mapping of acoustic fields.

LG Motion Limited, the Basingstoke based motion specialists has been a major supplier to Precision Acoustics over several years, providing motion controls, gantry positioning stages and test tank support frames as an integral part of these scanning systems that are used throughout the acoustics measurement industry - by the OEMs producing
medical and NDT ultrasound measurement systems as well as their users in hospitals, university research establishments and industrial test facilities.

As each UMS2 test tank system is effectively customised to suit its end-users’ requirements and the resulting positioning dimensions can vary, each system is effectively a special for LG Motion. To maintain the keen delivery times and competitive pricing that Precision Acoustics insists upon for each order, it was important from the outset to select modular and adaptable positioning stages, motion controls and support frame components that would suit these changing needs.

A typical specification for a test tank positioning system is a three axis XYZ gantry with a usable scanning area of up to 1000 mm x 1000 mm x 700 mm requiring a positional accuracy to <0.05 mm per axis over length of travel, with a positioning resolution to <0.002 mm. One of the most important requirements is for the scanner positional
repeatability to be <0.005 mm to guarantee that the ultrasound measurements are well within the bounds of the international standards used for transducer and hydrophone calibration. This is specified as a unidirectional value as the software takes care of system backlash by always positioning each axis from the same direction for critical
measurements.

Typical working load is less than 15 kg and the speed is up to 20 mm per second maximum. Each axis requires overtravel safety and home position limit switches and the Precision Acoustics software outputs a combination of PC serial port commands as well calling pre-programmed motion sequences stored in the motion controllers memory.

Both the modularity and specification requirements for the mechanical positioning system are completely fulfilled with LG Motion’s BiSlide range. Based on an extruded “I” beam aluminium profile with dual 45 degree opposing “V” ways for maximum rigidity in all load directions, the fully modular range includes low friction bonded PTFE compound
Ultrasound test tanks get LG Motion’s modular treatment bearing pads on the moving carriage with fully adjustable pre-load offering long life and minimal maintenance.

The range is supplied with 1.0 mm or 2.0 mm pitch leadscrews with an externally adjustable preload. The durable range is available in a wide choice of travel lengths from 125 mm to 2 metres with a compact cross-sectional profile of less than 90 mm wide and 40 mm in height. Multi-axis orientation is straightforward with integrated "T" slots providing endless configuration possibilities with stage to stage and stage to support frame interfacing using simple cleats and bolts rather than adapter plates; saving cost and further simplifying positioning system design.

The Precision Acoustics gantry is configured with dual, parallel X axes with one side motor driven and the other side supported by a simple linear bearing. The Y and Z axes are single BiSlide units. To achieve the resolution, each axis is driven by a NEMA 23 frame high torque microstepping motor set at 1000 steps/rev with a 2 mm pitch
precision leadscrew, To meet the accuracy and repeatability specifications, a motor mounted rotary optical encoder provides position verification via a Parker VIX500IM Microstepping Drive comparing theoretical and actual positions and making required corrections at the end of each move.

As the test tank is normally water filled, leadscrews and bearings are protected with covers which are a standard BiSlide option and each motor/encoder is housed in an enclosure with a fitted IP65 rated connector. Provision is also made to manually position axes with handwheels assembled on rear shaft extension on each motor. The complete
positioning system is supplied fully assembled, wired and tested and includes a ‘cable tray’ cable management system.

Control of each axis is made easy with the VIX500IM Microstepper Driver Indexer which is integrated into the overall software by Precision Acoustics. Independent high level commands for point to point moves via a serial link from a PC are mixed with preprogrammed motion sequences and synchronised I/O routines that are be stored in the
controller’s memory to speed and simplify programming.

The full modularity of each scanning system is made possible with support frames built with machine framing components from MiniTec UK Limited who have a very strong alliance with LG Motion. The MiniTec Profile System range of aluminium profiles and machine building components also includes the time saving Powerlock® fastening method that allows rapid assembly with no pre-machining or pre drilling. The extruded profile is simply cut to size and assembled using a simple M8 Allen key, making re-use and system adaptation a possibility if Precision Acoustics’ customer needs to modify its machine in the future.

LG Motion stocks a wide range of BiSlide linear positioners along with motion controls and other ancillary utomation components as part of its distribution agreements with Parker and other major motion equipment suppliers. This investment and its close relationship with MiniTec allows LG Motion to provide a rapid and competitive response to Precision Acoustics ever changing needs.

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Ultrasound test systems manufacturer gets LG Motion treatment

15 February 2010

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