Designing MAX

Behind the scenes of the revolutionary motor technology in the Inertia Wheels MAX.

NODO’s new MAX motors not only represent a leap forward in operating technology. They are also a world-first debut of a new type of motor, Printed Circuit Board (PCB) Stator Motors, which are integrated deep in the assembly of the wheel. PCB Stators solve a major dilemma in haptics by eliminating cogging. PCB Stator design is at the forefront of electric motor innovation. So how did NODO become one of the first to debut this technology?

The technology is credited to Boston-based startup ECM PCB Stator Technology and their proprietary PrintStator software platform.

NODO founder Boyd Hobbs and ECM engineer Ryan Duffy offered some insight into the collaboration and Inertia Wheels MAX product design.

Boyd Hobbs: Early in development, it was apparent that there were limitations with existing brushless motors. If we made the motor large and powerful, you could feel cogging in the motors—which feels like small detents in the handwheel during rotation. If we undersized the motor, the motor wouldn't have enough torque to perform the physics.

Ultimately the motor we chose for the first model was big enough for a good amount of torque, but we detuned it with software to the point that you couldn’t feel the cogging. This could sufficiently, consistently, and reliably generate weights that felt similar to conventional wheels and exceed them as long as the operators used finesse. However, the detuning can feel like springy-ness when changing wheel directions at higher weight.

For us to do better than this, we needed better motor technology. We began the search right away after a successful launch.

In early 2020, NODO reached out to ECM, and they hit it off. Ultimately, ECM's printed circuit board motors stood out. They were free of cogging and their inherent shape was ideal for hand wheels.

Using their software, PrintStator, ECM works with partners like NODO to rapidly design, model, and prototype optimized printed-circuit-board stator electric motors that are lighter, faster, quieter, and more energy and space efficient than conventional motors.

Ryan Duffy, Applications Engineering Manager at ECM: My first impression was that the project made perfect sense for our PCB stator technology... It was pretty obvious what the current limitations were and how a PCB stator motor would solve and improve on those.

We were also excited about how unique the application was as well. We get inquiries from companies around the world, but the fact that this motor would be integrated into a product that might produce award-winning films on the big screen made it that much more exciting.

Soon, NODO and ECM began developing the next generation of Inertia Motor™. ECM sent a draft motor design as a drop in replacement of the existing motor and everyone's wheels were turning.

Boyd: It outperformed our existing motor, but what stood out to me, as I looked at the design, was that we could turn the wheel into the motor and make them a single assembly—one big motor wheel.

Ryan: Traditionally, if an engineer had an application that required a motor, they would reference a motor catalog to pick a motor that is the closest fit to the power, size, weight, and electrical requirements for the application. However, this usually means they need to compromise on some other element of the final design for the application, meaning they need to design their system around the motor.

ECM operates in a completely opposite fashion. Our specialty is designing custom PCB Stator motors so you can design the motor around the system. We offer a perfect fit over just the best fit.

The MAX motor was indeed perfect. It had an amazing amount of torque and was impeccably smooth. But there was one problem in the way of its release: the motor driver. The existing motor driver was designed to move the original motors with a smaller current. The new MAX motors had much more torque and torque needs current. NODO spent several months redesigning the motor drivers for greater current capacity.

Boyd: Redesigning the motor driver took more resources than the motor itself—which is a testimony to ECM. We switched to a gate-driven motor driver. This required more chips, which was daunting in the peak of a chip shortage. Thankfully, we got the chips we needed. Since the first generation motors can also work with this motor driver, we began shipping Inertia Wheels with the bigger motor drivers in January of 2021 in anticipation of the MAX upgrades.

After the successful adoption of the new motor driver board, NODO turned the attention to one last detail: the appearance of the MAX wheels.

Boyd: The first MAX wheel design was created back in 2020 before we released the Third Axis. So the Third Axis is actually based on the original MAX design. But after spending a year with the Third Axis, I thought we could do better. After all, these motors are truly something special. It's rare that a product you can buy genuinely has a first-in-the-world bit of technology inside, so we wanted to really celebrate that.

Ryan: NODO was fully open to trying new concepts and pushing the design to be as radically different as possible. This made it very easy to agree on certain design elements and progress the design forward.

The final design of the motor and wheel is fantastic. Considering this was all built from the ground up, I was very excited to see everything work so well—especially considering all the new design features that we incorporated into it.

NODO was thrilled to partner with ECM to collaborate on this new motor technology. First, the partnership allowed us to create a powerful new product like Inertia Wheels MAX for our customers. Beyond that, we hope this will open the door to new uses of PCB Stator motors that will further innovation across the film industry.

ECM is on the verge of incorporating its PCB stator technology into large-scale production in many sectors of the consumer market including a continued partnership with NODO.

Boyd: ECM's motor technology has changed NODO's direction. There's definitely more coming down the pike with these motors. We're excited to be a leader in what comes next.