Catching Fire: PLC-Integrated Robots (Part 1 of 2)
There are always proponents and skeptics of new technology. Skeptics resist, maintaining nothing is broken, so why fix it? As a proponent of new technology, I believe its role is to accelerate productivity and to create a new approach to an issue rather than to fix existing problems.
The buzz about advances in PLC-integrated robot technology has grown louder over the last five years. According to The Association for Packaging and Processing Technologies (PMMI), integrated robot controls is one of the key trends in automation and control technology
Skeptics say this technology is not a viable solution. While I agree that PLC-integrated robots are not applicable for every application and industry, they do make robot controls more familiar and easier to use in many applications.
What is a PLC-integrated robot?
First, let’s consider the traditional approach to robotic work cells. Typically, robots are programmed through a proprietary robot controller and in a proprietary robot language. A supervisory PLC is interfaced with the robot through Input/Output (I/O) or messaging signals over a fieldbus network. The supervisory PLC controls the robot’s actions based on events in the work cell. If everything in that environment works as planned, nobody cares what happens in the “black box” that controls the robot. If the cell stops working, plant maintenance staff must immediately find a robot expert who may or may not be readily available.
With a PLC-integrated robot platform, the robot is programmed and controlled entirely through the PLC and in the PLC ladder logic. There is one controller (PLC) and one language (PLC language) for the entire work cell; there is no need for a separate robot controller. This single control strategy is referred to as “unified controls architecture”.
A PLC-integrated robot is programmed in the same way a robot is programmed with a traditional robot controller. All user frames, tool frames, blended motions and I/O synchronizations are available through the PLC.
When should PLC-integrated robots be used?
PLC’s are ideal for discrete operations and event handling logic. PLC-integrated robots, by definition, are then best-suited for applications such as material handling, palletizing, picking and case packing.
Path-dependent or process-centric operations such as welding, dispensing, deburring and polishing are better-suited to utilize proprietary robot controllers.
Many industries, such as consumer product goods, food and beverage, paper and plastic utilize robots for discrete operations. I believe that companies in these industries will tremendously benefit from PLC-integrated robot technology.
In my next blog we will discuss how the unified controls architecture of PLC-integrated robots helps boost productivity.