Smooth-moving robots cut energy consumption

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By minimizing the acceleration of industrial robots, and optimizing the sequence of multiple robots, energy consumption can be reduced by up to 40 percent(Credit: Chalmers University of Technology)

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With their precise mechanical movements, robots seem like the most efficient of workers, but they can actually waste a good deal of energy. Chalmers University of Technology is developing a new optimization tool that acts like an efficiency expert for industrial robots by smoothing their movements to reduce their energy consumption by as much as 40 percent.

According to the researchers, robots in robot-intensive manufacturing industries, such as automotive bodywork factories, are responsible for consuming around half the power used in production. A large part of this is wasted – not by what the tasks robots are programmed to do, but how they do them.

If you watch an industrial robot in action, you'll notice that its movements lack grace. Instead of moving with fluidity, it lurches suddenly from one position to the next, halts, waits a bit, then lurches again. It's this hurry-up-and-wait strategy where energy is wasted.

Developed and tested by Chalmers for the EU Areus project, the new optimization tool is an algorithm that allows robots to carry out the same task in the same way and in the same time, but with much greater efficiency. It reduces acceleration, deceleration, and the time a robot spends standing still – all of which waste energy. At the same time, it leaves the overall production cycle untouched.

"We simply let the robot move slower instead of waiting for other robots and machines to catch up before carrying out the next sequence," says research leader Bengt Lennartson. "The optimization also determines the order in which the various operations are carried out to minimize energy consumption – without reducing the total execution time."

The researchers say that it isn't enough to optimize one robot on an assembly line. Since robots often work together, they need to be optimized together. The optimization tool studies how the robots move in concert, determines how to make sure they don't collide, and that they hand off to one another efficiently. The tool generates new commands that are run directly by the robots.

In preliminary tests, the tool cut energy consumption in individual robots by 15 to 35 percent, and multi-robot systems by as much as 40 percent. According to Kristofer Bengtsson, who is responsible for the implementing the new optimization strategy, years of evaluation, testing and development are still needed before the new tool is fully practical, but he hopes that it will one day be an optimization standard.

The team's results were presented at the IEEE International Conference on Automation Science and Engineering conference in Gothenburg, Sweden.

The video below shows the effects of the optimization tool on a KUKA robot.

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