Canadian Startup Says Direct-Drive Motors Are the Future of Robot Actuators

Genesis Robotics has designed a direct drive that integrates magnets and windings tightly in a compact package. The company says its LiveDrive motor can deliver three times as much torque per weight as conventional direct drives, a decades-old technology.

A vast majority of robots still use an electric motor coupled to a gearbox to move each of their wheels and joints. The motor spins rapidly, as it’s optimized to do, while the gearbox reduces the rotation speed of the output shaft, increasing the torque in the process. This type of actuator powers robots as varied as industrial arms, walking humanoids, and Mars rovers.

Now a Canadian startup says there’s indeed a better way to actuate robots. Genesis Robotics in Langley, B.C., wants to replace regular motors with a special kind of motor whose torque and speed can be controlled more precisely. Because such a motor can turn at a much slower pace, you can sometimes use it to power a robot joint using no gearing at all, which is why the design is known as a direct drive, even though in many cases these motors are coupled with minimal gearing.

“Robotics is so far forward with the controls, with the sensors, with the AI,” says Genesis founder and chief technology officer James Klassen. “What’s holding it back is actuation.”

The 60-person company has been amassing patents over the past several years, and last April it received a large investment from Koch Industries, the giant conglomerate. Starting in 2019, Genesis will either sell or license its family of direct drives and gearboxes to robot makers.

The company has designed two LiveDrive models, one 250 millimeters in diameter and another 110 mm. Public demonstrations at trade shows have generally impressed observers, and Genesis is now collaborating with researchers to improve its motor specs.

“The diameter is a bit big, but on the other hand, the width is very impressive,” says Bram Vanderborght, a roboticist at the Vrije Universiteit Brussel, in Belgium, who’s an advisor to the company and has been testing the 250-mm LiveDrive. One possibility he’s considering is putting two or more LiveDrive units side by side to multiply the torque. “It’s a more modular system,” he says.

Most robots will require more torque than LiveDrive alone can provide. That’s why Genesis created its Reflex gearbox. It’s based on a configuration of planetary gears, with smaller gears revolving around a larger one. This design results in a more compliant, responsive actuator compared with those used in multistage gearing systems. Reflex will initially be made out of metal, but the goal is to fabricate it using plastics, bringing down the cost to a fraction of that of existing strain-wave gears, which is a major reason why robotics hardware is so expensive.

For his part, Klassen says the best way to show off the benefits of his actuators is by putting them to use in real robots. His team has designed robotic arms, legged robots, and exoskeletons and is now building a home robot prototype. “We love to build things, make things better,” he says. “We’re a bunch of gearheads.”

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