Why attitude control is the new design bottleneck
Advanced orbital operations require attitude determination and control systems (ADCS) that offer high agility, low power budgets, and dependable reliability. Traditional setups force mission designers to make hard compromises between the simplicity of reaction wheels and the torque efficiency of control moment gyroscopes (CMGs).
In a recent discussion, Julien Hennequin, Head of Sales at Taiwanese ADCS innovator Tensor Tech, outlined how hybrid actuation technologies are changing these design trade-offs. By combining the advantages of reaction wheels and CMGs into a unified hardware and software solution, the company is enabling new capabilities for platforms ranging from nanosatellites to 400 kg smallsats.
The actuator dilemma: CMGs vs. reaction wheels
For most small satellite missions, reaction wheels are the default choice because their control laws are straightforward and well-understood. They generate torque by accelerating or decelerating a flywheel. However, scaling reaction wheels up for larger platforms or highly agile maneuvers introduces significant mass and power penalties.
Our technology is kind of hybrid solution between reaction wheels and CMGs. We can accelerate or decelerate our wheel… that allows us to go around the singularity.
In contrast, traditional CMGs operate flywheels at a constant speed, generating torque by gimbaling the spinning mass. While exceptionally power-efficient — which is why they are utilized on large-scale platforms like the International Space Station — CMGs are notoriously difficult to control. They suffer from mathematical singularities: specific geometric configurations where the actuators cannot produce torque along a requested vector, effectively blocking attitude maneuvers.
Tensor Tech addresses this constraint directly with a patented hybrid architecture. Unlike traditional CMGs, Tensor Tech’s system can dynamically vary the speed of its flywheel in addition to gimbaling.
By combining these control methodologies, the platform bypasses singularity states, drastically simplifying the underlying control algorithms and delivering the high torque of a CMG with the operational simplicity of a reaction wheel.
Spherical motors as the core technological enabler
At the heart of Tensor Tech’s hardware is a significant deviation from traditional rotor design: the spherical motor. Standard CMGs require two separate, dedicated motors to handle rotation and gimbaling axes. Tensor Tech’s design replaces this complexity with a single spherical motor utilizing coils that surround a central wheel embedded with a permanent magnet.
This induction-driven movement eliminates the mechanical overhead of secondary drive motors on the wheel’s axis. While the company’s long-term research includes fully unconstrained 3-axis reaction spheres, launch environment survival demands lock mechanisms to prevent the internal sphere from acting “as a pinball” during launch. Consequently, the current design optimizes this spherical motor technology for a highly reliable, compact, and robust 1-axis gimbaled CMG configuration.
Optimizing for remote sensing and in-orbit servicing
The performance profile of these hybrid CMGs makes them particularly well-suited for two high-demand mission profiles:
If you are aiming for long complex maneuvers, sometimes in-orbit servicing requires operations with robotic arms and so on. That’s where our system is also very, very interesting.
- Agile remote sensing: Earth observation missions require rapid slewing to capture multiple targets along a single orbital pass. Hybrid CMGs allow satellites to point and settle significantly faster than reaction wheels, maximizing data yield per orbit while operating under strict power constraints.
- In-orbit servicing & space debris mitigation: Operations involving robotic arms or complex proximity maneuvers demand prolonged attitude adjustments without saturating actuators. When reaction wheels reach their maximum speed limits, they must halt maneuvers to dump momentum via magnetorquers. The high momentum storage capacity of Tensor Tech’s system prevents premature saturation, ensuring long, uninterrupted maneuvers.
Scaling up and expanding to propulsion integration
While Tensor Tech established its flight heritage through the rapid lifecycle of CubeSats and nanosatellites, the company is actively scaling its technology for larger platforms up to 400 kg, including an active demonstration project with the Taiwan Space Agency. This expansion includes upgrading hardware designs to support higher radiation resilience and passive redundancy.
Furthermore, the company is expanding beyond pure attitude control by exploring integrated orbit control. Tensor Tech is actively developing interfaces to bridge their ADCS suites with both electric and chemical propulsion systems, paving the way for complete, unified guidance, navigation, and control (GNC) packages.
Streamlining GNC: from hardware-in-the-loop testing to rapid delivery
Integrating components from disparate vendors remains a major bottleneck in satellite development. Tensor Tech addresses this by manufacturing a comprehensive suite of in-house ADCS components — including sun sensors, magnetorquers, and control boards — excluding only star trackers, which they source through dedicated industry partners.
We are able to deliver a full system… in less than six months… from first contact to delivery in space… so that’s the level of flexibility we need to have.
A key differentiator in their development methodology is their commitment to hardware-in-the-loop (HIL) testing. Unlike teams that rely solely on software simulations, Tensor Tech validates every system on an in-house air-bearing testbed. This environment features a solar simulator and a Helmholtz cage to replicate orbital magnetic fields, providing high-fidelity physical testing before shipment.
This integrated approach to hardware and software allows for highly compressed delivery timelines. In one standout deployment, Tensor Tech delivered a custom, turnkey ADCS solution for a tandem 6U CubeSat formation flight mission just three months after initial client contact.
By offering support equipment that allows firmware upgrades to be flashed in parallel with mechanical integration, the system can adapt to evolving mission parameters right up to launch.
Learn more
To explore how these hybrid control moment gyroscopes can optimize the power, mass, and pointing agility of your next orbital mission, contact Orbital Transports to discuss your specific ADCS requirements and simulation options.