Parallel-link robot deployments will continue to see strong growth as more and more operations across all industries embrace automation as a way to cut costs and stay completive. When light payloads and very fast cycle times are required, whether it be assembly, picking, dispensing, or any number of other applications, parallel-link robots will continue to meet the challenge.
David Bruce & Raad Asmaro | FANUC Robotics America
Parallel-link robots were initially deployed with great success in three and four-axis variations in the picking and packaging industry. A picking application is one where the output is a specific pattern of product and the input is a random or semi-random stream of that same product. Often, machine vision and conveyor tracking are employed directly with several parallel-link robots in one large picking system handling an overall system throughput of several hundred parts per minute. Packaging involves placing several products into a package such as a shipping box or other container. Often the output of a picking system will flow directly to a packaging application. Many different industries make use of picking systems, including food, medical, electronics, cosmetics, etc.
The M-3iA is now working in a variety of industries from an automotive engine facility to scoring of un-baked bread. Compared with most parallel-link robots that are limited to either three or four-axes, the FANUC M-1iA and M-3iA are unique. The six-axis variant combined with a three-axis wrist allows for the completion of tasks which involve manipulating parts and/or tooling at compound angles. By combining a three-axis wrist with the speed and precision of a parallel-link robot, and the integrated intelligence offered by all FANUC robots, FANUC Robotics is rapidly making possible the automation of many tasks which are now either manual or done by expensive hard automation.
Intelligence is more than just a buzz word in the robotic industry, it is an ever-increasing reality. Both force control and machine vision are becoming more and more prevalent as part of industrial robot systems, especially with assembly operations. In an ideal world, parts line up and fit perfectly; however, in the real world work pieces require a wiggle or visual adjustment. Machine vision and force control are increasingly able to handle these realities, and when combined with a parallel-link style robot, the cycle time of each operation falls dramatically, which reduces the number robots required and the return on investment timeline! With picking applications, machine vision is employed in conjunction with conveyor tracking to accurately track a random product on a moving conveyor belt at speeds as high 1400 mm/sec (275 ft/min). The machine vision camera will continually snap and locate product at some point upstream of the parallel-link robots. When a product is identified by the camera, its location is combined with the current position of the conveyor belt. As the product enters a robot work area the robot is able to accurately move to the product and either pick it or work on it while matching the current conveyor speed. Parallel-link robots are the preferred style for this type of application since the amount of time the robot deals with each product needs to be as short as possible in order to maintain the usually very high system throughput.
While the payload of parallel-link robots is considerably less than that of serial robots (6kg vs. >200kg) their use of intelligence is still as strong. Remote force sensing is now used to accomplish difficult assembly applications quickly using six axis parallel-link robots. By remote mounting the force sensor, small six-axis parallel-link robots are able to make use of this game changing technology. Vision cameras can be mounted directly to a parallel-link robot’s tooling, or fixed-mounted in the robot’s work envelope.
Machine vision is increasingly used for inspection either before a part is put into an assembly or after the assembly process is completed, and Parallel-link robots can make this process quicker and more cost effective. How? By simply adding a single camera to several different inspection points or to an existing assembly to catch problems before they happen, or eliminate bad assemblies from the supply chain before they enter it .
Like all robots, parallel-link robot deployments will continue to see strong growth as more and more operations across all industries embrace automation as a way to cut costs and stay completive. When light payloads and very fast cycle times are required, whether it be assembly, picking, dispensing, or any number of other applications, parallel-link robots will continue to meet the challenge.
The content & opinions in this article are the author’s and do not necessarily represent the views of RoboticsTomorrow
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