© Svetlana Kuzmina (iStock)
June 2024

Goodbye hydraulics!

By Carsten Paulun
Humanoid robots such as the newest Atlas version from Boston Dynamics or the Unitree H1 are becoming more powerful, nimble, and agile. Electric motors instead of the previous hydraulic units increasingly operate in their arms and legs. That’s a clearly discernible trend in other industrial applications as well.

More customer benefits, more efficiency, more sustainability – the same reasons speaking in favor of the electrification of vehicle powertrains ensure that hydraulic and pneumatic drive systems are being replaced by electric actuators in industrial automation, medical device technology, and various mobile machines – as well as in humanoid robots such as Atlas or H1.

Unitree H1 Robot
The electric Unitree H1 measures 180 cm (5’11") and weighs 47 kg. (104 lbs.) Its battery has a capacity of 864 Wh, roughly the same as a top-end electric bike battery. It runs at a speed of 12 km/h (7.5 mph), setting a new record for humanoid robots© Unitree
Less susceptible, less maintenance, more precision

Keep it simple: Compared to hydraulic or pneumatic systems electric actuators can do without additional components such as pumps, hoses, pressure, and oil reservoirs. That simplifies the sometimes-complex design not only of robots but also of industrial machines. Plus, the electric motors reduce the machines’ susceptibility for trouble and maintenance requirements. A compilation of video footage of the previous Atlas model in which occasional spraying of hydraulic fluid from its joints when the robot falls can be seen shows that as well.

The utilization of electric instead of hydraulic solutions prevents losses due to leakage and the related potential harm to the environment.

Due to switching from hydraulic to electric “joints,” the new Atlas generation from Boston Dynamics has become slimmer and more mobile

Another argument supporting electric drives is the fact that they’re clearly more compact as shown by a visual comparison between the current Atlas model and its predecessor. The change in drive technology has produced clear progress in terms of agility as well. For instance, the new Atlas can rotate many of its joints by 360 degrees, enabling the robot to execute movements that we as humans cannot accomplish.

Plus, the benefits that electric drive systems of humanoid robots offer can be applied to industrial machines as well, for instance in the form of electric linear drives. Not least due to their simpler design, they offer more opportunities in terms of system integration because launches are less complex and therefore faster. Compared to their hydraulic and pneumatic counterparts, electric linear drives simplify controlling the process parameters of force, position, acceleration, and speed. The precision and dynamics they offer result in benefits regarding smooth in-position running, stable intermediate positioning without mechanical stops, and precise compliance with programmed travel profiles over time, irrespective of changing loads and frictions. In addition, the electric systems have adequate elasticity as Unitree’s H1 has long demonstrated. As the first electric humanoid, it managed a backward somersault, a feat that only hydraulic robots used to be able to pull off.

Humanoid robots ready to go

By 2030, production-level, highly flexible robots with fine motor skills that are superior to those of humans are supposed to be available, according to a “Humanoid Robots in Operations” market analysis by the consulting firm Horváth. It says that it can be assumed that as early as in 2025 less capable humanoid robots will be mass-produced for industrial uses.

Better energy efficiency reduces the carbon footprint

Obviously, the aspect of energy efficiency should not be neglected either. Hydraulic or pneumatic drive systems operate with compressors initially converting electric power into pressure and then into motion which, by design, results in low efficiency. Consequently, only 44 percent of the input power in a hydraulic system arrives at the load, compared to over 80 percent on electromechanical systems. An even greater energy-related advantage is the fact that electric drives consume power only as needed whereas hydraulic or pneumatic systems require permanent pressurization, which consumes energy. Currently, the subject of energy is still one of the major challenges posed to developing humanoid robots, which, for that very reason, tend to be sprinters rather than marathon runners.

Robotic applications by Schaeffler

Schaeffler offers far more than just a wide range of roller bearings for robotics. The company defines itself as a strategic partner for these system components: precision gearboxes, pivot bearings, drive motors, sensors, and the 7th axle. Especially the Modular Precision-Drive-System (pictured below) saves time and costs of integrating a precision drive into industrial automation. Additional information about Robotic Applications by Schaeffler can be found here.

Goodbye hydraulics!
Modular Precision-Drive-System from Schaeffler© Schaeffler

In addition, compressors or hydraulic pumps are noisy, require additional installed space, and produce waste heat. Moreover, both hydraulic and pneumatic systems are rather maintenance-intensive, the required pilot valves are sensitive and trouble-prone.

Those reasons contribute considerably to the success of electromechanical actuators. Unsurprisingly, there’s hardly any industrial sector anymore not using that technology. Listed below are some examples of uses beyond humanoid robotics.

  • Packaging industry: In the past, pneumatic cylinders were frequently used on pac ...
    Packaging industry: In the past, pneumatic cylinders were frequently used on packaging lines for sealing and labeling of product packs. Electric linear drives are a cost-efficient alternative for those uses. In addition, they enable more precise positioning and control, for instance for gripping and sorting of products and packaging.

    © Schaeffler
  • Medical device technology: In medical equipment such as CT scanners and X-ray ma ...
    Medical device technology: In medical equipment such as CT scanners and X-ray machines, electric linear drives are used for controlling the motion of components. They’re less noisy and more precise than hydraulic or pneumatic systems and satisfy the strict requirements for precision in medical imaging settings. Electric actuators are also used in operating tables, medical chairs, and surgical robotics, rehab, and fitness equipment. © Schaeffler
  • Mobile machines: Combines, working platforms, forklift trucks, and other commerc ...
    Mobile machines: Combines, working platforms, forklift trucks, and other commercial vehicles – manufacturers and users are faced with the major challenge of simultaneously reducing costs and emissions while increasing operating efficiency. That’s where electromechanical actuators can display their strengths (higher precision and reliability, higher energy efficiency and lower maintenance in operation), so replacing the previously used hydraulic or pneumatic systems. © Schaeffler
  • Food processing: In the food processing sector, electric linear drives are used ...
    Food processing: In the food processing sector, electric linear drives are used in conveyor belts, packaging and filling lines, and labeling equipment. They ensure high-precision positioning and a hygienic environment. In addition, they’re easy to clean compared to hydraulic systems. In coffee machines, electric linear drives exhibit low friction and enable features such as easy height adjustment for dispensing coffee into varying cup sizes. © Schaeffler
  • Automotive industry: In automotive manufacturing, hydraulic systems used to freq ...
    Automotive industry: In automotive manufacturing, hydraulic systems used to frequently be employed in robotic systems such as those used in spot welding, application of adhesive bonding and seals, riveting, and folding. Here, electric linear drives have replaced hydraulic systems because they offer more precise controlling options, and better energy efficiency. In materials handling technology and in final assembly settings, electric linear drives offer those benefits as well. © Schaeffler
  • Aviation: In the aerospace industry, electric linear drives are increasingly use ...
    Aviation: In the aerospace industry, electric linear drives are increasingly used in the control systems for aircraft and spacecraft. They provide reliable and precise control of aircraft flaps and other movable parts.
  • Facility automation: Electromechanical actuators have become integral components ...
    Facility automation: Electromechanical actuators have become integral components of any digitally interlinked facility control system. They open and close windows, doors, and gates, as well as blinds, dome lights, terrace roofs, smoke flaps, and heat flaps. Even state-of-the-art theater stages such as the world’s largest one at Berlin’s Friedrichstadt-Palast move by means of large-sized electromechanical actuators.
Whether robotics or linear actuators – Schaeffler offers the suitable electric solution
Goodbye hydraulics!
Schaeffler serves the fast-growing “Linear Motion” business field with a wide range of electromechanical linear drive systems© Schaeffler

For Schaeffler, it’s clear that the future of actuators lies in electric ones – in the case of robots just like in industrial settings. Schaeffler defines itself as a strategic partner for system components in both worlds. For robotics, in addition to its wide range of roller bearings, the company offers strain-wave and planetary gears, modular Precision-Drive-Systems, complete solutions for articulated arms, and more.

To enable offering its customers tailored and powerful industrial solutions in the form of electric linear technologies from a one-stop shop, Schaeffler has concentrated all its activities in this area in the “Linear Motion” business field. Schaeffler Linear Motion’s portfolio encompasses various product groups for far more than 100 different industrial and specific customer solutions – whether in stationary or mobile uses.  Global sales of electric linear drives are planned to grow by 67 percent by 2032, from 20.5 billion U.S. dollars in 2022 to then 34.3 billion U.S. dollars.