Robot Maintenance Issues

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Within a company or plant there are a number of issues involved in selecting robots which are not always compatible with selecting the best robot to perform the task. Maintenance issues must be considered. Different robot manufacturers all produce their own control systems (some produce more than one) and many produce their own drive systems. This means that maintenance personnel require different specialist training in order to be able to deal with each different manufacturers robots.

The areas where variations can give difficulties are electric connections (power supply, safety circuits and signalling), programming language and operating software. The electrical connections are not generally too much of a problem as company standards will set out how these are to be done but differences in the robot programming languages and operating software can cause problems where maintenance staff are not all familiar with them. To get around some of the possible problems a PLC is sometimes included in the cell to handle most of the signalling requirements rather than doing this within the robot controller. Provided the PLCs are standard throughout the factory any member of the maintenance staff should then be able to deal with problems in the machine communications. Most companies also restrict the choice of robot vendor to give some standardisation in robot controller.

Over the past 10 years, there have been a number of projects performed in academia looking at producing a standard robot programming language. These have never been widely adopted as people buying robots have not specified them and manufacturers of robots have continued with development of their own languages to try to get a technology lead over their competition. At some stage in the future when the development of robot programming languages slows down I believe that a standard will emerge. This may well be the Programming Language for Robots (PLR) which is currently under development by the International Organization for Standardizartion (ISO).

Another maintenance issue is the requirement to re-program robots after maintenance of the arm or replacement by another apparently identical arm. This is caused by the difficulty of setting up the datums or zero points on the robot axes which leads to every robot arm having a different arm signature. Tools and methods of setting the robot zero points have been developed, but as yet these are complex, expensive systems which cannot always be used with the robot installed on the shop floor. Some makes of robot are better than others in this respect and in general the more recent the robot design the less likely you are to suffer from these problems.