Active Stabilization

Moog offers Active Stabilization on several Pan & Tilt product lines, designed for applications where line of sight stabilization is needed to counter low frequency disturbances. Typical applications include surveillance poles and towers, small boats and ground vehicles with low frequency motion.

Active Stabilization rejects platform motion to maintain the target of interest in the center of the FOV. The system integrates motion sensing and position control electronics inside the P&T in a classic PID control loop architecture.

Product Application

  • Security Poles: Typical motion for pole sway can be about ±2º maximum at less than 0.2 Hz will vary depending upon pole height and construction
  • Boats: Typical motion for medium size boats can be about ±10º at 0.1 to 0.5 Hz but will vary depending upon boat size and sea state
  • Ground Vehicles: With Low Frequency Motion Disturbances are highly dependent upon the vehicle and terrain
  • Sensor Integration for the follow:
    • Radar Antenna Systems
    • Multi-Spectrum Cameras (Visible/NIR/SWIR)
    • Thermal Imagers (LWIR)
    • IR and Visible Illuminators
    • HD and Megapixel Cameras
    • Laser Range Finders
    • Communication Antennas
    • Acoustic Devices

System Description

Active Stabilization rejects platform motion to maintain the target of interest in the center of the field of view. To accomplish motion rejection the system integrates motion sensing and position control electronics inside the pan and tilt in a classic PID control loop architecture. The system uses an internally mounted MEMS gyro and processing circuitry integrated directly into the drive and feedback system of the pan and tilt. The job of this closed loop system is to keep the system continually pointing at the desired target.

The MEMS gyro measures three axes of platform rotational motion, returning angular rates to the processing electronics. This information is then converted into commands to the motor drive electronics. The pan and tilt holds its angular position by commanding the motors to counter the movement of the platform. The loop is closed by the processing electronics, which monitor the position of the encoders to ensure the commanded position was reached.

Performance

Stabilization reduces the impact of platform disturbance on the payload line-of-sight. Stabilization performance for Moog products is defined by a measure we call Rejection Ratio, which is a very simple yet direct way of conveying system performance.

In mathematical terms, rejection ratio is the magnitude of the disturbance divided by the resulting line of sight motion. A 16:1 rejection ratio simply means that for given disturbance of 16Ú, the system will maintain the line of sight of the payload within 1Ú of the target. Because stabilization performance varies with disturbance frequency, we provide performance at various frequencies to ensure that customers know exactly what they're getting with our product.