Energy-Efficient Robot Deployment Strategies
| By: Emmet Cole, Contributing Editor
The level of interest and concern regarding robot-related energy consumption varies from region to region, depending mostly on local energy costs, but energy efficiency is a topic “everywhere,” says Eric Potter, General Manager at automation giant FANUC.
“Everybody wants to save energy. Everybody knows the benefits of it. There are environmental benefits when it comes to the effect on nature and there is also a lot of focus on energy cost savings and how to lower operational overheads,” says Potter.
Electricity consumption by autonomous mobile robots (AMRs) is not necessarily “top of mind” among end-users challenged by labor shortages and the pressures of seasonal demand on production and throughput, says Daniel Theobald, Chief Innovation Officer and founder at Vecna Robotics, a warehouse automation solutions provider specializing in high-capacity AMR solutions.
“As we enter the holiday season, everybody is just trying to survive and deal with peak. But energy consumption is a really important topic in the long-term and if we don’t pay attention to energy efficiency now, it will come back to bite us,” says Theobald.
Whether reducing electricity consumption is top of your priority list this year or not, there are several simple, practical steps you can take to optimize your automation-related energy bill.
Rightsize your robot
Avoid the temptation to purchase robots with capabilities that far exceed the requirements of your application, advises FANUC’s Potter.
“Lightweight robots will inherently use less energy. So, don’t just take the simple route of getting a heavier payload robot just because you know it will work. Rightsizing the robot so you can use the smallest one you can for the production you are trying to run will provide inherent energy savings,” explains Potter.
Using the right robot for the job is a smart way to reduce energy costs, says Vecna Robotics’ Theobald.
“There is much efficiency to be gained by having a mix of equipment and robot types with different capacities and then orchestrating them efficiently. We often see facilities where all material handling equipment has been sized for the maximum load ever expected in the facility, yet in practice are carrying loads a fraction of that weight most of the time,” says Theobald.
Simulate your application
Robot simulation software allows you to create a digital twin of your proposed automation deployment. You can test the impact of different payloads and grippers, swap one robot out for another and most simulation software packages will be able to determine the amount of electricity your proposed robot cell will consume.
Vecna Robotics’ Pivotal software, for example, contains a simulation module that allows end-users to construct an entire digital twin facility and from there to estimate and optimize electricity consumption.
FANUC’s RoboGuide software also provides offline digitization tools that enable end-users to test different automation setups to determine which ones provide optimal electricity usage for the application.
“RoboGuide allows you to do all your energy estimations and trials and figure out the right placement of equipment, the right kind of motion, and the right size robot --all before you even order anything,” says Potter.
Optimize your deployment
Optimization takes place on different levels. Path optimization, for example, ensures that your robot selects the most efficient trajectories when performing a task.
Additionally, rearranging elements around the robot can help reduce power consumption.
“Simply changing the robot cell layout and making things easier for the robot will reduce your energy bill,” says Max Erick Busse-Grawitz, Technology Transfer Manager at precision drive maker Maxon.
Humans are great at solving local optimization problems, such as the best way to load a truck, but terrible at solving global optimization problems, such as identifying which human and automation resources should be deployed on a particular task at a particular moment in time in a busy warehouse or production facility, says Vecna Robotics’ Theobald.
Pivotal software solves this problem by processing all the data collected globally throughout a facility and assigning automation and human resources accordingly, notes Theobald: “Better data, better information, and flexible automation that allows you to react effectively to that data will save you far more energy than small improvements in AMR motor design.”
Watch your speed
Minimizing the acceleration of industrial robot systems can reduce energy consumption by up to 30%, according to researchers at Chalmers University of Technology.
Energy is wasted when robots accelerate and decelerate too quickly, so avoid operating your industrial robots at maximum speed all the time, says FANUC’s Potter.
“If you have your robot going as fast as possible, in a lot of cases you will find that you are going to spend time waiting for other machines and equipment to finish. Instead, set the robot at the speed that the system needs it to be so that it doesn’t spend a lot of time sitting around waiting. It’s a lot more energy-efficient if you can smooth out the motion versus going really fast and stopping and waiting for a bit and then going really fast again. This enables you to optimize your energy consumption as well as increase the lifespan of the robot,” says Potter, who notes that several facilities have policies in place that require all equipment to be operated at around 70-80% of top speed for cost savings and to have a buffer for increasing production capacity.
Managing electricity consumption is good for your bottom line and good for the environment, but looking beyond end-user power usage, the automation industry has an important role to play, says Theobald, citing MassRobotics’ work on the development of interoperability standards around a common charging infrastructure for all equipment, including robots, as an example of how industry can combine efforts to improve sustainability: “Industry should all work together to help promote this idea that energy efficiency is important. It’s more possible than ever to design energy efficient systems, so why wouldn’t we?”
A motor that can get a lot of torque out of a little inertia is preferable to a motor that can get a ton of torque but requires a ton of inertia to do so. Efficiency depends not only on the pure motor efficiency, but also on the motor inertia. So, you need a favourable ratio between motor torque and motor inertia. This is called the mechanical time constant. The lower the mechanical time constant, the better. - Max Erick Busse-Grawitz, Technology Transfer Manager at Maxon.