Monthly Archives: October 2021

Five Reasons Why ThinGap Is A RWA/CMG Motor Leader

From aerospace to motorsports, many industries rely on ThinGap’s cogless motor technology. One of the largest applications for ThinGap’s patented motor technology has been active control systems for satellites. Satellites of all sizes require the ability to control their orientation in orbit, what is referred to as “Attitude Control.”  Whether commercial or defense in nature, LEO spacecrafts need Attitude Control that enables high accuracy pointing capabilities so that desired objects of interest, point-to-point communication or optical platforms can be effectively utilized.

Active control systems, such as Reaction Wheels Assemblies (RWA) and Control Moment Gyroscopes (CMG), require highly efficient motors for torque and actuation. With two lines of high performance slotless motors — both with space heritage, ThinGap’s cogless motor technology is well suited for these Attitude Control solutions.

Here are the top five reasons why ThinGap is the industry leader for RWA and CMG motors.

  1. HIGH EFFICIENCY | For reaction wheel motors, ThinGap supplies ironless or “air core” stators made of fine stranded wire for the coil. This lends itself to very low drag at high operating speeds, with a significant improvement over traditional iron core slotted motors. Additionally, the torque capacity is increased across the full operating range for the same momentum storage capacity.
  2. HIGH TORQUE AND INERTIA-TO-WEIGHT RATIOS | ThinGap’s ironless stator puts all the magnetics, the heaviest part of the motor, in the rotor. This maximizes the inertia for a given weight and size requirement. The reaction wheel’s necessary flywheel mass can be reduced, and sometimes fully incorporated into the rotor. The resulting package is lighter weight for the same momentum storage capacity.
  3. HIGH PRECISION | ThinGap’s motors use a wave-wound coil, which results in a back EMF that is sinusoidal with a total harmonic distortion of less than 1%. When paired with a sinusoidal drive, torque ripple is minimized and much lower than similar motors. Additionally, the ironless stator produces absolutely zero cogging motion. In combination, these aspects produce the highest precision RWA motor available.
  4. DYNAMIC RESPONSE | Due to no iron saturation in the stator, ThinGap’s peak torque capacity is much higher for a similar weight motor. This gives a dynamic response significantly better than the competition at a lighter weight.
  5. COMPLIANCE AND CAPABILITY | ThinGap designs and builds its motors in the USA and provides highly engineered solutions and program support. Since 2015, thousands of Space-grade or MIL-STD rated motor parts have shipped for use in commercial satellites, UAVs, military aircraft, and NASA flight programs.

The TG Series‘ and TGR Series‘ high-speed, high-efficiency is ideal for momentum-wheels in both RWA and CMG. The LS Series’ high-torque, lower-speed precision movement is perfect for gimbal applications, like those in a CMG architecture and related Satcom and Optical applications.

Since 2015, ThinGap has shipped thousands of space-grade or MIL-STD rated motor parts for use in commercial satellites, UAV, military and commercial aircraft, and flight-grade NASA programs.

ThinGap’s Motor Tech Covered By Partner Sierramotion

ThinGap’s motor technology has been covered in a very informative article by our close business partner Sierramotion entitled “DIRECT DRIVE – AN ENGINEER’S GUIDE”.

The Applications Team at Sierramotion recently posted a blog on their company’s website where they outlined the desired motor performance in Direct Drive applications, focusing on characteristics such as zero-cogging, and large internal diameter.  While ThinGap was not mentioned by name (no vendors were), an image of the LS Series slotless motor kit was prominently shown.

One interesting excerpt from the post related to motors is sited below:

“The accurate definition of a motor has to do with its mechanism for generating torque or force and how many electromagnetic phases it has and how they are controlled/commutated. Electromagnetic (EM) torque/force production is derived from an interaction between two magnetic fields or through a change in reluctance or permeance with position/angle, (or some combination of these two main groups). There are four main electromagnetic motor types in use today; brush commutated DC or AC motors, electronically commutated Synchronous Permanent Magnet Motors (AKA Brushless DC), AC Induction Motors (AKA Asynchronous), and electronically commutated Variable Reluctance (AKA Switched Reluctance). Of course, there are hybrid combinations of these technologies also in use. There aren’t any new forms of EM torque generation, in spite of what you may read on the internet.”

To read the complete Sierramotion post, click here

How Gimbals Work

One of the largest use-cases for ThinGap’s slotless motors are Gimbals, so much so that it considers itself to be the performance leader in Gimbal motors. From handheld applications for action cameras to large platforms designed for satellite-to-satellite communication, the applications of gimbals are endless. By using an array of different sensors and motors to counteract movement, electrically controlled gimbals serve to keep platforms stable and focused.

The three forces that gimbals are designed to counteract are tilt and pan (directional horizontal rotation), and roll (vertical rotation). These three axes of movement are counteracted by the sensors and electric motors that work to counteract the forces enacted on the platform. No matter the orientation, whatever is on the platform is held stable and even. By counteracting the forces of gravity with brushless electric motors, orientation can be held indefinitely (within reason). In the world of airborne and space Gimbals, three-axis refer to the angular movement as being Azimuth, Elevation, and Roll.

Image Credit: ResearchGate

In large systems, such as Turrets, the inner design works as a Gimbal allowing for control over roll movement and can be used in aircraft and satellites. On aircraft, optical platforms such as infrared, visible light, and lasers can be mounted on a Gimbal platform that is then fixed to a turret and placed within a fairing to protect it from aerodynamic forces.

Satellites use Gimbals for communication in a similar method for pointing and positioning, with the gimbals acting as the turret and gimbal unit alone, and a device called a fast-steering mirror delivering fine precision control that ensures a reliable optical data connection between satellites, either between low Earth orbit and geostationary satellites and between low Earth orbit satellites. This communication is conducted through pulses of laser light that transmit digital data in a similar manner to Morse Code used by telegraphs of the 19th century but in a far faster manner.

Image Credit: JAXA

What makes ThinGap motors ideal for Gimbal applications is the unique motor architecture that provides smooth movement. This smooth movement is zero-cogging which is afforded by ThinGap’s patented method for distributing stator coil wire windings within a thin cross section that eliminates traditional stator teeth, resulting in a motor without cogging torque.

Cogging is an unwanted magnetic torque disturbance caused by the winding patterns around the stator’s iron teeth that are the basis of “slotted” motors. Slotless motors eliminate cogging torque and offer smooth motion that is critical to optical systems for precision aiming, point and zooming at long standoff distances, and smooth motion for precise scanning.

ThinGap’s line of slotless motor kits feature high-performance, zero-cogging, high efficiency, and a lightweight design. The motor kits are ideal for smooth and precise motion. The entire LS Series offers a large through-hole and a low-profile form factor, ideal for integration into a wide range of different platforms. LS motors offer torque performance equivalent to traditional frameless motor kits available on the market, but unlike other slotless motor solutions, does not require a trade-off between torque output and smoothness.