TWI Industrial Member Report Summary 874/2007
By D M Calder
Off-line programming (OLP) is a technique which allows an industrial robot to be programmed and reprogrammed without taking it out of production. OLP is achieved by using robotic simulation and programming software. This software provides the ability to 'build' a robot cell, complete with components and manipulators, in a three dimensional virtual environment. The model of the robot in the simulation contains kinematics data for the robotic machines in industrial use.
Simulation provides the ability to analyse, modify and develop the physical features of robot manufacturing applications before committing to the use of real hardware. These systems provide the user with the ability to accurately model robot cells and thereby check accessibility to the component, the sequence of events that the robot(s) will action and detect potential collisions between elements within the cell. OLP provides the ability to take the simulated motions of the robot(s) and manipulator(s) and create a robot program, which can then be downloaded into the actual robot controller(s).
The approach offers further benefit by enabling complex three dimensional or non-geometric profiles to be programmed into the robot very rapidly. The basis for the control of the robot movement may also be taken directly from computer aided design (CAD) data for the component or product being processed. Direct use of CAD data enables the OLP user to utilise computer aided design/computer aided manufacture (CAD/CAM) or computer integrated manufacture (CIM) techniques all the way to the robotic production cell, and furthermore, enables the use of simultaneous engineering principles, where product and process development is carried out in parallel.
The level of use of OLP within manufacturing varies geographically, with greatest uptake in Japan and the USA. Within the EU, Germany is the leading adopter; the UK has been relatively slow to invest in the approach. Where investment has been made within the UK, the major automotive users dominate. The UK Small to Medium sized Enterprise (SME) base is investing ever more in robotics and the costs associated with OLP are reducing, therefore the opportunity to enhance productivity using the technique is now within the reach of smaller enterprises. The aim of this report is to inform SMEs that may be considering OLP, about the implementation requirements and the essential considerations, together with quantifying some of the potential benefits.
The report describes, in detail, the preparation required to undertake an OLP task at TWI, and the learning that resulted, with the aim of providing new users with a useful guide document. The on-line 'help' materials and the basic training provided for the OLP software do not fulfil that requirement, and it is intended that potential users find value in the experiences captured by this work and are made aware, in advance, of the practical issues associated with the technology.
TWI has experimented with OLP in the past, however the software package utilised in this study represents the latest evolution of the technique enabled by the rapid advance in computer technology. An essential element to this work programme was therefore to bring TWI up to date on the latest developments with the approach, and to ensure that a robust skill-base was developed within the relevant parts of the organisation.
To carry out a practical OLP laboratory assessment, and in so doing, identify the key areas of concern, the risks and the benefits for potential adopters of the technology.