The Gold Standard servo is unique in the industry.
When Trio introduced the altitude hold systems, we did so only when
we felt that we had designed a "safety-conscious" servo that we were
comfortable connecting to an aircraft elevator system. (It is
used for both aileron and elevator systems).
The Gold Standard servo
has inherent "intelligence" capability acquired by the two internal
microprocessors that govern its operation. It has full
authority to disconnect itself from the controls if it senses
anything that deviates from normal operational conditions. It
watches motor driver currents and temperatures (both servo and
auto-trim) as well as short circuits. It monitors crank arm
positions and will disconnect (and alert the pilot) in abnormal
circumstances - i.e. extreme elevator/aileron positions. It
obeys the "G" force limitations dictated by the A/H control
electronics and it will disconnect itself if it detects a
communications error. It has a slip clutch to allow
pilot override in emergency situations. It fully disconnects
the internal gears when not engaged and the pilot will not feel any
"system drag".
In short, the Gold Standard servo borders on being paranoid about
your safety.
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All
digital electronics for accuracy and reliability
The servo communicates, via a high-speed
bidirectional data bus,
with the altitude hold control module. This unique
capability allows it to inform the control module (and the
pilot, via the LCD switch screen) of any unusual activity within
the servo. For instance, it can notify the pilot if
the clutch is not properly adjusted. If critical activity is
reported, the control module will immediately remove all power
from the servo, releasing the elevator and (if installed)
automatic trim system.
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Dual microprocessors monitor all functions for safety (an industry
first!)
The
Servo Main Processor (SMP) controls all servo functions.
It also monitors communications from the motor and trim drivers,
and it constantly listens to the "heartbeat" signal from all
other processors in the system. If it detects any
anomalies it will provide an alarm and disconnect from the
aircraft controls.
A Supervisory Processor continuously monitors the Servo
Main Processor to ensure it is executing its program as
designed. It looks for the “heartbeat” signal from the SMP each
10 milliseconds. If for any reason the processor does not
provide a “heartbeat” signal to the supervisory processor for a
period of 65 milliseconds the supervisory processor will
unilaterally cut power to the safety disconnect solenoid and the
trim and servo motor drive circuits.
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Triple protected motor drivers continuously report their condition to
the microprocessors
The integrated circuits used to drive the servo
and trim motors are internally equipped to detect and report to
the SMP a variety of fault conditions including:
1. High side (supply side) short to ground (low
side)
Low side short to high side
2.
Under voltage lockout
3. Over temperature condition
The SMP will immediately disconnect upon receiving any of these
fault messages.
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Complete motor and gear train disconnect when not engaged - free from
system drag
The servo contains a solenoid that allows a complete disconnect
of the servo gear train whenever power is removed from the
solenoid. Power can be removed under program control of the
System Main Processor (SMP), the supervisory processor or
whenever power is interrupted by the AH module. In
addition, it is advisable to always install an easily accessible
circuit breaker or switch in the aircraft power line to the
system.
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Reliable slip clutch (adjustable to your airplane) provides immediate
pilot override
The servo
employs a clutch, which allows the pilot to override the servo
by applying moderate force to the control stick. Even though
the solenoid will hold the gears in place, the clutch will then
slip and allow the control surfaces to move. In the event of
strong turbulence, or an altitude anomaly, the pilot can thus
override the servo to control the airplane.
The slip clutch may be employed freely without any damage to the
system. The clutch function does not rely on a shear pin
failure mechanism as is sometimes employed on other autopilot servos.
Servo Dimensions are here
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