MOMENTUM WHEEL 8W-1.8 Nms

ALMASpace's Momentum Wheel has been designed as part of ALMASat-1 ADCS subsystem in order to provide a Three Axis stabilization of the microsatellite acquiring the demanded angular momentum and compensating the external disturbance torques along the pitch axis.

The Momentum Wheel is controlled via a Digital EC Controller studied for brushless motors and produced by Maxon Motors, successivelly modified for space operations. The DEC can operate as open or closed loop speed controller by regulating the command input voltage between 0-5V and acquiring the output signal from the three Hall sensors integrated inside the motor's housing.
The motor itself is a custom version produced from Maxon Motors using particular internal bearings with gold spheres and high performances internal lubrication in sealed structures.
The whole Momentum Wheel's housing is modular and adapted to the ALMASat fleet's structural requirements: the picture below shows the internal configuration of the actuator, highlighting the possibility to scale the size of the motor and the fly wheel in order to cover a large number of applications for different demanded missions.
In order to increase the precision of the angular speed acquisition, a magneto-resistive incremental encoder is mounted on the bottom of the motor, leading to an accuracy of 1 rpm on the nominal value.

Every single part of the Momentum Wheel has been tested in a vacuum thermal chamber to space-qualify the actuator by eliminating every possible anomaly or malfunction that could compromise the mission of the mounting spacecraft.