More applications requiring stabilizing video or photography on a moving object or tracking satellites or objects in navigation applications have led to the need for multi-axis gimbals in military, aerospace, industrial, and commercial applications. The gimbal acts as a rotating stage allowing an object to rotate in multiple axes (pitch, yaw, and roll) relative to the mounting vehicle.
Active image and video stabilization become necessary when attempting to get a usable image on a moving vehicle. The vibrations created by a vehicle, either a helicopter, plane, drone, boat or automobile, cause the motion in the camera system that would cause blur or a shaky video that leads to undesired results.
Another primary usage of powered gimbals in aerospace and defense applications is ensuring proper communications through satellite tracking. The motors are algorithmically programmed to direct themselves at satellites. With a powered gimbal, the tracking software can eliminate the need to make adjustments due to hard to predict turbulence or vibration.
Sensor tracking is also a typical use of a powered gimbal system. Many systems need to maintain a laser on an object; therefore, the gimbal maintains the precise location of such a system’s laser to preserve signal and proper calibration, even in the presence of vibration caused by rough terrain or vibration.
Traditionally, the motion has been accomplished with rotary motors with either gearing or belts. This approach allows for high torque capacities, but the backlash in the motor can make fast movements impossible. Therefore, a direct drive approach, using rotary voice coil actuators has been integrated to eliminate many connections and allows for quick changes in the direction and higher speeds in the gimbal motions. This allows for their use on a greater number of devices where high acceleration vibrations are present.
A rotary voice coil actuator generates a force based on an interaction of current-carrying conductors in a permanent magnetic field. The force generated by the voice coil is proportional to the current flowing through the coil and the magnetic flux in the permanent magnetic field, as dictated by Lorentz’s force equation.
The moving coil design ensures a hysteresis-free movement as the coil is wet wound and self-supported, and the non-commutated coil allows for ripple-free motion and no cogging. The rotary voice coil actuator has been designed with mounting provisions in the magnet and coil assemblies. This allows for the integration into the gimbal while maintaining the clearances between the coil and permanent magnetic field assemblies. The rotary voice coil actuator is ideal for applications requiring high torque and high-speed applications.