Mclennan helps STFC solve large load precision motion control

Mclennan has completed the design and supply of a particularly challenging motion control system for the STFC Daresbury Laboratory, as part of the research council’s funding and collaborative support of the Advanced GAmma Tracking Array (AGATA).

With its objective to build and operate the ultimate gamma ray tracking spectrometer, AGATA is a partnership of over 40 institutions from 13 European countries that collaborate and share exciting research that will produce the most valuable understanding of the structure of atomic nuclei ever realised. At detection levels that are one thousand times more powerful than previous systems, the globe-shaped instrument will be transported and used across several European beam accelerator facilities for applications that will advance many areas of research including medical imaging and environmental monitoring.

Mclennan’s work on the project with Daresbury Laboratory, which is located at Sci-Tech Daresbury, involved the design and supply of single axis servo-controlled motion system for the precise rotary positioning of the sensor array holding frame that guides and supports a matrix of encapsulated high-purity and highly fragile germanium crystal detectors. Mclennan had been involved in two earlier iterations of the AGATA project which has run for several years.

The earlier motion systems were simpler and more traditional than the on-axis drive required for this latest holding frame design which measures approximately 2.5 metres over its largest diameter and weighs 7.5 tonnes when fully loaded with a complement of up to 180 large detectors.

The closed loop motion system needed to be applied through an existing slew ring gearbox that forms part of the holding frame’s power transmission mechanics and includes a large drive shaft supported on two bearing blocks. With such a large mass and an equally large total system inertia - plus the problems of lost motion/hysteresis, backlash, and compliance through the combination of the slew ring gearbox and bearing arrangement – accurate and stable rotary positioning for this huge spherical structure would present challenges for Mclennan. These challenges were compounded by the specification requirements and choice of technologies for the additional gear unit components and servo system performance.

Other design criteria included a requirement to use a stepper motor as part of closed-loop motion system which through its characteristic holding torque had proved to be more stable in earlier projects. STFC had already specified and included a Renishaw RESOLUTE series BiSS C 26-bit absolute encoder to form a part of the closed loop motion system. This modular tape and reading head optical encoder system was placed around the outer diameter of the slew ring gear assembly to directly monitor the actual angular position of the load. The 26-bit resolution provided more than adequate angular positioning and accuracy capability with Mclennan’s servo system.

To maintain a stable closed loop system, reflected load to motor inertia matching is fundamentally essential and to suitably pair the huge inertia mismatch, avoiding a large, unwieldly and costly motor solution, Mclennan worked with its distribution partner Wittenstein to integrate two precision gear units that together provided an 80:1 reduction ratio.

Wittenstein’s SP140S series at a 10:1 ratio and its NP025 series at 8:1 are inline planetary gear units that were supplied as a single assembly. This compact gear unit combination allowed the use of a comparatively small 34 NEMA frame stepper motor to adequately power the massive holding frame. With the reflected inertia taken care of and the closed loop to the load-located absolute encoder a critical factor, Mclennan specified a TXM34Q series StepSERVO integrated stepper motor from another of its distribution partners, Applied Motion Products.

StepSERVO technology combines the high torque capabilities of a step motor with the closed loop dynamic control of a servo system as an all-in-one housed solution. This drive solution features a digital drive, a motion controller and a selection of control and bus communications interfaces. Servo feedback is normally achieved through an internally housed encoder, however for this project Mclennan’s own PM1000 series digital servo controller managed closed loop control with the absolute encoder, outputting step and direction pulses to the TXM34Q integrated stepper’s control interface.

The PM1000 was modified with special firmware to accommodate the BiSS C absolute encoder interface. Overall control for the handling frame was manged by STFC’s supervising PC through motion commands to the PM1000 via RS232. Mclennan also interfaced a jog box to the PM1000, allowing manual control as part of the requirement specification.

The complete control system was housed in a 4U, EMC compatible 19-inch rack enclosure, complete with power supplies. The TXM34Q integrated servo included M12 connectors for all interfaces and all interconnecting cables were supplied for integration with STFC’s cable management system. The commissioning of the system was remotely guided by Mclennan engineers as the delivery requirements fell into COVID restrictions – normally all on-site commissioning and training is part of Mclennan’s terms of supply.

Mclennan

Unit 1, The Royston Centre
Lynchford Road
Ash Vale
GU12 5PQ
UNITED KINGDOM

+44 (0) 1252 531444

sales@mclennan.co.uk

www.mclennan.co.uk

More news
15 hours ago
RS Components partners with HMS Networks
RS Components has partnered with HMS Networks, a leader in industrial information and communication technology, to significantly expand its industrial equipment networking solutions offering.
20 hours ago
Mouser Electronics receives TDK’s top distribution awards
Mouser Electronics has received three top distribution awards from TDK. Mouser was honoured with TDK’s Global Best Performance Award for Fiscal Year 2022, North America Distributor of the Year for Calendar Year 2021, and European Distribution Award in High-Service Distribution for 2021.
1 day ago
White Paper addresses assembly challenges
Resolve assembly challenges instantly with Henkel’s new high performance LOCTITE 402, an innovative instant adhesive that also improves workplace safety. Download the all-new white paper here.
1 day ago
Schaeffler organises worldwide Climate Action Day
June has seen Climate Action Day at all Schaeffler locations worldwide, with every one of the approximate 83,000 Schaeffler Group employees stopping work for 90 minutes to focus on climate issues.
1 day ago
Yokogawa helps Solar Team Twente to solar challenge win
Yokogawa’s WT5000 precision power analyser has been used by Solar Team Twente to win the first ever Solar Challenge Morocco. The WT5000 helped the team to squeeze every last watt out of its car’s solar power system, ensuring it crossed the finish line of the 2,500 km course in first place.
1 day ago
HVACR OEM relies on Emka locking technology
When HVACR OEM Hansa Klimasysteme needed new connecting elements for the corners of its air-conditioning units to stabilise the housing cube, suitable for die-casting, it turned to Emka.
2 days ago
LEM holds inauguration ceremony for new production plant
Electrical measurement specialist LEM has held an inauguration ceremony in Penang, Malaysia for its new production plant. The ceremony marked a major step in the plant’s construction with the first electric current sensor products expected to come on-line in Q1 2024.
2 days ago
ITI acquires digital manufacturing specialist Cimlogic
ITI, one of the UK’s largest independent systems integrators, has acquired Cimlogic, a leading digital manufacturing solutions and services provider to some of the world’s largest manufacturers.
3 days ago
Atlas Copco saves precision sheet metal manufacturer over £6,000 a month
When Constant Group, a Manchester-based supplier of sheet metal parts, components, and fully assembled fabrications pieces were let down by their previous service provider for onsite high-pressure nitrogen generation, they turned to Atlas Copco for help.
3 days ago
Timber plant reduces downtime with NSK linear guides
Thanks to the adoption of NSK’s linear guides with K1 lubrication units, a timber manufacturer managed to reduce conveyor downtime by a factor of more than 12, prompting annual cost savings of more than €77,000.

Login / Sign up