Q&A: PCB stator technology integrated by ECM, Cone Drive into robotic joint actuators
Article by Eugene Demaitre, Senior Editor at The Robot Report, originally published September 24th, 2020 on The Robot Report.
ECM PCB Stator Technology and Cone Drive last week announced that they have integrated ECM’s printed circuit board stator technology with Cone Drive’s Harmonic Solutions drive technology to create small but powerful actuator packages for robotic joint applications.
Newton, Mass.-based E-Circuit Motors Inc., which does business as ECM PCB Stator Technology, designs and develops printed circuit board (PCB) stators to power fans, pumps, and small vehicles. Traverse City, Mich.-based Cone Drive has been a subsidiary of The Timken Co. since 2018. Its products are used in industrial robots, semiconductor and medical equipment manufacturing, and aerospace.
The companies said they have designed and prototyped a hollow-shaft robotic joint actuator that is half the weight and half the axial length of any previously available integration. Cone Drive and ECM claimed that their technologies can increase motor efficiency, improve battery life and reduce energy costs, and add design flexibility.
ECM replied to the following questions from The Robot Report about PCB stator technology.
How did ECM start? What was the inspiration?
The company’s story began in 2015, when a team of innovators was investigating the concept of printed circuit board stators, first recognized in the 1980s, and envisioned a world where motor designs were immediately developed and printed from discrete inputs. We quickly concluded that design software could optimize copper geometry and winding patterns even further, producing machines with incredible precision, high efficiency, and superior torque density.
Later that year, ECM launched its suite of proprietary design optimization and smart manufacturing software, collectively named PrintStator, and used it to successfully design and prototype a mid-drive solution for an electric bike.
What advantages do PCB stator motors offer above those with standard copper windings?
The PCB stator design eliminates the need for wire winding and iron laminations used in conventional motors and generators by embedding copper-etched conductors into a multi-layered printed circuit board. PCB stators work with permanent magnets to form axial flux motors and generators.
PCB stators are a fraction of the size of conventional motor windings and use up to 80% less copper, enabling power-dense motor/generator designs that are incredibly thin and lightweight. Beyond our design’s reduced envelope, PCB stators are fully encapsulated in an epoxy and include no iron, resulting in a new durable motor design with little acoustic noise.
Why isn’t this design topology more common?
When the concept of a PCB stator was introduced, there was a large gap in power electronics required for the technology. Beyond controlling the motors, manufacturing custom PCB designs in the 1980s was also heavily limited.
At ECM, we have capitalized on the momentum of the circuit board and power electronic industry, creating a brand-new patented PCB stator design and manufacturing software. Fully utilizing the capabilities of customizable circuit boards, our software communicates directly to established PCB houses for immediate printing.
PCB stator and robotics
Why are PCB stator designs good for robotic applications?
The PCB stator design allows for a highly customizable range of highly efficient robotic applications that feature a superior quality of motion, increased power density, and reduced weight. The lack of iron in PCB stators results in low electromagnetic interference [EMI]. Our ability to fully customize the winding patterns and geometry with our software results in power-dense, efficient machines that were previously unavailable.
Furthermore, our design’s flexible form factor allows for compact integration with a variety of torque multipliers, increasing power density even further. Increased motor efficiency improves battery life for mobile applications and reduces energy costs for stationary ones. In addition, our tech enables hollow-shaft designs, which adds to the technology’s flexibility.
You mentioned that ECM’s actuators achieve “a superior quality of motion” — why is this important to the robotics industry?
Without iron, ECM’s stator design eliminates cogging torque and produces continuous smooth motion. Our motor design is loaded in the in-plane direction, eliminating out of plane forces acting on the stator and reducing the tendency for the design to encourage buckling or plate deflections.
Robotic applications that require an elite level of precision, such as precision manufacturing and surgical robotics, are limited by current motor motion quality. Additionally, robotic designs which require a significant gear reduction will benefit from this characteristic.
PrintStator could help robotics developers
How can PrintStator assist robotic developers in comparison with conventional motor catalogs or integrations?
PrintStator fundamentally changes the way motors are designed, produced, and integrated. From discrete motor specifications, PrintStator immediately produces a series of PCB stator designs with exact operating characteristics optimized for a variety of selected motor elements including efficiency, cost, for factor, and mass.
The idea is that by using PrintStator’s design capabilities, robotic developers will no longer be confined to existing motor catalogs of manufacturers and will have be able to design unique PCB stator solutions with their exact operating characteristics and application-specific form factors without having to “reinvent the wheel.”
What other design advantages does PrintStator offer its designs?
Besides increasing the capabilities of modern robotic designs through customized PCB solutions, PrintStator features a suite of software that challenges the modern idea of motor design and production. PrintStator’s design-optimization software allows for the targeted reduction of resistance and eddy current losses by manipulating copper geometry and thickness. This can result in superior torque density and motor efficiency.
PrintStator’s smart manufacturing software considerably reduces design cycles and motor development costs by enabling rapid prototyping. PrintStator can transform exact system requirements into a unique PCB stator motor in only a matter of hours.
PCB stator applications and looking ahead
ECM’s motor’s produce low levels of EMI. Which robots or applications might benefit from this characteristic?
The smooth operation of sensors and other electrical equipment in close proximity relies on minimum EMI machines for the most accurate observations. Specifically, robotic assisted surgery, military surveillance, and oceanographic research are a few of the areas where low EMI is extremely important.
With PCB stator-integrated machines, surgeons will be able to collaborate with new assistive robotics without disruption to vital monitoring devices, tactical machines involving side-scanning sonar will be completed with increased accuracy, and automated oceanographic research vessels will provide far less disruption to underwater ecosystems.
What other applications have PCB stators motors been used in, and when can we expect to see these motors in everyday life?
We’ve been involved in numerous applications across a broad range of electrified applications. In the past, we have integrated PCB stator tech into a variety of high-tech projects involving automated vehicles, industrial and medical robotics, gimbal systems, and maritime transportation to name a few.
Recently, we have begun to integrate our tech into more consumer end-use products including electric bikes, HVACR pumps and fans, propulsion motors, and kitchen appliances. Needless to say, the technology is taking off, and we are confident that you’ll see it in day-to-day life very soon, if you haven’t already.
What do you see for the future of this technology?
PrintStator will become a global tool for developing more sustainable and higher-preforming solutions for PCB stator motors around the world. It may be in robotics, HVAC, e-mobility, aerospace, or a new type of application none of us have seen — we hope to assist the innovators and disrupters of the world to create a greener and better future. Corporations, inventors, students, and manufacturers around the world can try PrintStator.