Marsa Gyro1 Tilt Module

The Marsa Gyro1 tilt module is the most advanced tilt measurement systems for rocket avionics currently available. It attaches to the Marsa54L, 54LHD and 33LHD expansion header and provides rocket rotation data to the altimeter.  Also the tilt module features a 100K barometric sensor which extends the Marsa altimeter's Kalman filter for better accuracy on those high altitude flight

Why 2 gyros?

Current altimeters with tilt capability that use a single gyro have a significant performance compromise.  A rocket in flight can rotate about its 3 axes.  These are spin, pitch and yaw.  The latter 2 rotations are the ones that we are primarily interested in for staging applications.  In a rocket flight the pitch and yaw rotations occurs at a slow rate (hopefully). However for a high altitude flight these very low rate rotations can add to a significant tilt angle for which we would want to inhibit a sustainer motor ignition.

The spin rotation is one we usually do not care too much about. In fact a decent spin rate can help to stabilize the rockets direction.  The spin rotation rates can be very high compared to the pitch and yaw rates of the rocket.  However you still need to measure this spin rate accurately to accurately calculate the attitude of the rocket.  Devices that use a single gyro have to set the gyro sensitivity low to be able the measure the spin rate.  As a result the accuracy and resolution suffers for the rates that are really important (yaw and pitch).

Marsa Systems solution is simple, one gyro set for the sensitivity to measure the spin and another gyro set up to accurately measure the low rotation rates of yaw and pitch.

 

Programming Tilt Events

When a Marsa Gyro1 is connected to the Marsa altimeter it is detected and tilt awareness is applied to any channels programmed for timer-motor events.

A global tilt parameter menu is used to program the tilt related constraints for the motor-timer event.

The first line sets the angle limit for the timer channel to fire.

The 3rd line sets a maximum speed limit for the staging event.  This allows a flight profile that lets the rocket coast down to a predetermined speed before the channel fires.

The second line sets the condition for the speed constraint. The options are "Try", "Require" and "Ignore"

"Try" attempts to let the rocket coast down to the target speed but if the rocket is at the maximum tilt angle before the target speed is reached the channel will fire.

"Require" will not fire the channel until the target speed is reached AND the tilt angle is less than the allowable set angle.

"Ignore" ignores the speed parameter and fires the channel at the preset delay at the time delay programmed for the timer.