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Lightweight gear-motor-drive kit could slash robot costs

04 February, 2021

The German engineering plastics specialist igus has developed a lightweight, low-cost gearbox with an integrated motor and controls which, it says, could cut the cost of collaborative and service robots. The modular gearbox kit consists of a tribo-polymer strainwave gear, combined with a brushless, external-rotor DC motor and controller, force control electronics, and an absolute encoder.

Later this year, igus plans to use the plug-and-play gearbox in a new version of its low-cost Robolink ReBel robot which will be even smaller and more cost-effective than the current version. “Our goal is to offer the ReBeL on the market for €2,900, even for small order quantities,” says igus’ head of low-cost automation, Alexander Mühlens. “It should be able to carry 2kg, have a range of up to 650mm, as well as a self-weight of less than 10kg, and a minimum running time of 2 million cycles.”

The company also sees great potential for the gearbox in robotic applications in areas such as agriculture, logistics, nursing and automated kitchens and bars.

“We see market opportunities in robots whose total weight is less than 8kg,” says Mühlens. “This is because, where robotics in low-cost automation is concerned, the self-weight is always important – not only the payload and a low price. Lightweight robots are easier to transport and can be used more efficiently on driverless transport systems, on seventh robot axes or, in the near future, even on drones.”

Low weight is also a significant advantage in cobots because smaller masses mean that lower forces are generated if collisions occur. The new gearbox’s built-in double absolute encoder can be used to determine forces as well as torque, and to limit the forces safely via the motor current. The encoders take measurements in front of and behind a joint to detect forces and torque levels and react accordingly.

Last year, igus introduced a new generation of tribo strainwave gearboxes for the fifth axis of robots. The lubrication-free tribo-polymers reduce friction and wear, and result in compact, cost-effective designs. The strainwave gears, called drygear, can be used on the last axis of articulated arm, linear or delta robots – in front of grippers, for example.

The new modular gearbox extends the portfolio, and igus says that its plug-and-play capabilities will allow “exciting” cobot ideas to be implemented quickly, without having to worry about the power electronics. It is based on a tribo wave generator and a tribo flex ring with external teeth.

igus’ integrated strainwave gear-motor (top) and an exploded view (below)

The modular gearbox, which will be available in sizes 80 and 105, will make its public debut at the virtual version of the Hannover Fair taking place in April. The system will also be available on the online market, where users can combine robot kinematics with vision, safety or gripper components. igus promises that everything will fit together, on both the hardware side and software sides.

“With our low-cost automation solutions, we enable design engineers to cost-effectively take part in the future of service robotics,” says Stefan Niermann, igus’ vice-president for low-cost automation. “This opens up space for new ideas in the area of automation: robots that can dispense coffee in retail shops or clear out the dishwasher at home. Cobots, that can be used in the area of nursing as well as in industry.”


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