Applying a Concept for Robot-Human Cooperation to Aerospace Equipping Processes

摘要

Significant effort has been applied to the introduction of automation for the structural assembly of aircraft. However, the equipping of the aircraft with internal services such as hydraulics, fuel, bleed-air and electrics and the attachment of movables such as ailerons and flaps remains almost exclusively manual and little research has been directed towards it. The problem is that the process requires lengthy assembly methods and there are many complex tasks which require high levels of dexterity and judgment from human operators. The parts used are prone to tolerance stack-ups, the tolerance for mating parts is extremely tight (sub-millimetre) and access is very poor. All of these make the application of conventional automation almost impossible. A possible solution is flexible metrology assisted collaborative assembly. This aims to optimise the assembly processes by using a robot to position the parts whilst an operator performs the fixing process. Parts are measured prior to positioning, with datum locations on both parts and counter parts processed using a best-fit algorithm to balance misalignment. The robot is then used to position and hold the part whilst an operator performs the installation processes. The problem with this approach is that existing legislation requires separation distances and safeguarding methods that would complicate and limit its application. In this work a safety control strategy is proposed that allows closer integration of robot and operator and manual fixing of components with the drives active. Instead of assuming worst case scenarios for proximity, relative velocity and inertia, as is the case with current legislation and the fixed 2D detection zones of existing safeguards, multiple variables are processed in real time to interpret safe separation distance dynamically. In order to allow practical evaluation of the approach, a metrology assisted demonstrator cell has been constructed at Cranfield University where a typical equipping process is performed using realistic parts. To support the eventual implementation of this methodology a full study of the human factors issues is also being undertaken.