Step Design Ltd has recently supported Field International UK by completing the electrical installation and testing of a pedestrian-controlled, self-propelled and elevating trolley for use in the aerospace industry.
When Field International UK's resident electrical engineer fell ill and was unable to continue working on a high-value project, the company called upon the services of Step Design Ltd (SDL) to complete the electrical installation and testing of a pedestrian-controlled, self-propelled and elevating trolley. Following successful completion of the project, SDL was invited back to undertake the electrical installation and testing of a second trolley.
Field International's pedestrian-controlled, self-propelled and elevating trolley is manufactured with a rigid steel base structure carrying the wheels and steering, lifting frames, hydraulic power pack, battery pack and control equipment. The wheels, steering and hydraulic power pack are driven by DC motors, with power derived from an on-board battery pack that is recharged from a built-in battery charger requiring an external 230V AC supply. The photograph shows one of the trolleys under test in Shanghai, complete with an 11-tonne proof load supported above the trolley.
The Trolley is designed to be towed behind another vehicle prior to being operated in situ under the aircraft. The tow end wheels can be linked to a tow bar that provides steering during the towing operations.
Importantly, the trolley has a number of safety features and interlocks to prevent injury to the operator and/or damage to the aircraft. It also has five axes of precision motion control for the accurate positioning of the landing gear while under the aircraft. These servo axes are: X, Y, pitch, roll and slew. Each axis is positioned in turn using an HMI to manipulate the load (the aircraft landing gear) into position; in this case the landing gear is for the new Airbus A380 passenger aircraft.
There are now seven of these units in service around the world, and Step Design has been involved with the most recent two. The equipment is manufactured and CE marked in accordance with the Supply of Machinery (Safety) Regulations 2008 (the UK implementation of the EU Machinery Directive 2006/42/EC).
The control system comprises a Mitsubishi Fx3U PLC and associated special function modules including both analogue input and output modules, plus a Profibus DP module for communicating with the five Schneider Electric ILA1B572TB1F0 Lexium integrated servo motors/drives that handle the motion control. Programming and configuration of the drives is via a dedicated software package. PLC software is written in both Ladder and STL using the Mitsubishi GX developer package. The HMI (a handheld Mitsubishi Handy GOT with an STN colour LCD screen) is designed and configured using Mitsubishi's GT Works 3 package.
Follow the link to find out more about the programming and system integration services available from Step Design Ltd.