Watson Industries, Inc.
SPS-P230 Rev A 10/17/2017
5
derive a motor voltage that drives the error to zero. In other words, the servo-control system
ensures that the motion of the platform matches that of the joystick commands.
The servo driver module in the mount enclosure accepts commands from the micro controller in
digital form, converts them to pulse-width modulation using two full-bridge switching motor
drivers and then applies the modulated signal to the two motors.
The platform is carefully designed to be rugged and reliable. Particular attention has been paid to
minimizing the effects of noise at every point in the system. This ensures that full advantage can
be taken of the low noise performance of the gyroscopes a highly stable platform.
Joystick Controller
The Joystick Controller has a joystick, four buttons, four led indicator lights and three connectors.
The joystick controls the positioning of the SPS-P230 payload. The joystick itself is used to pan
and tilt the payload. The indicator lights and buttons that are used to inform the operator or to
control the operation of the SPS-P230 in different ways.
Operation
Start-Up
The system is automatic. Once power is applied, the stabilized platform system will drive to its
preset home position with any errors corrected by using a short time constant. The time constant of
the corrections is increased in increments until it reaches the full operational time constant. The
initialization mode has a 10 second duration. Please allow a 30 second warm-up before operating
the unit.
Time Constant
The operational time constant of error correction is chosen for the predicted influences on the
accuracy of the system. Chief among the sources of error are the dynamics of the vehicle and the
drift tendencies of the gyroscopes.
Vehicle dynamics are characterized as being violent when they exist for a short time and gentle
when they are sustained over a long period. They are derivative in nature. In contrast, gyroscopes
have little error in the short term, but these errors grow rapidly as they accumulate in the system.
They are integral in nature. The time constant must be chosen to match the circumstances such that
the least error is likely as shown in example the below:
