Started planning 737NG Autothrottle.Have a few questions, hoping a kind gentleman with experience could give me answers..- Stepper motors.. As I understand it there is no feedback from the motor itself, like there are from servos. Movement is based on pulses given from a controller moving the motor a certain amount of steps clockwise or counter-clockwise. "Calibration" is based on the controller "counting" number of pulses given (+/-) thus calculating the position. So far so good, but what happens when A/T is off and the handles are moved manually. Invoking any speedmode or TOGA thereafter - wouldnt the controller then have lost its knowledge of the current position??- Anyone successfully used Steppermotors and FSBUS to implement moving throttles? Program example for FSBUS Router? - Is there ONE FSUIPC Offset (for MCP or CDU auto-throttle setting) that can be used as input for controlling the throttle levers? Or are there many offsets depending on which mode is active?Regards,Ole J. Almenningenhttp://www.737cockpit.nohttp://www.simbuild.com

If the stepper motors and encoders work anything like they do in my telescope drive, then yes, they will loose their position if they are manually moved from where they thought they were when calibration took place.Wish I could help you out more.

Ole,There should be no need to keep track of the stepping motor's rotational position. Ultimately it is the throttle position that matters, and you already have a sensor on that, the throttle pot.I don't use FSBUS so can't comment on how you would implement A/T functionality within it. However, looking at the problem strictly as a feedback system, it appears to me that a simple PIC based controller could be used to interface and control the motor. The PIC would have very basic functionality: Motor on, Motor off, One step forward, One step back. With A/T turned on the motor is turned on which basically locks the throttle in its current position. (Depending on the size of the motor, it could be manually moved with some difficulty). You would need a software module on your PC to implement the A/T functionality. It reads the current throttle position and compares it to the desired position. If too low it sends a "One step forward" command to the stepping motor controller. If too high it sends a "one step back" command. The A/T software should get activated periodically to check throttle positions and send step commands as necessary. When A/T functionality is turned off, the "motor off" command is send to the motor controller PIC and the A/T software is no longer periodically activated.Mikewww.mikesflightdeck.com

Thanks, guys!Well, the Stepper controller is already there. The FSUBS stepper controller (hope I've got it right here..) gets its setpoint from the FSBUS Router program based on a fsuips offset to ones liking. Min. step, max step, stepping speed and ramp are paramterized in the Router software, and rest is up tp the Amtel chip controlling the actual stepper motor. There is also a "Reset controller" command which I guess sets the zero position (resets the step no. contained in the Amtel to zero). For the throttle levers, based on your skilled answers, it seems to me there is no way other than trying to implement some kind of "controller" within the FSBUS Router CCC function. Anyway, I have sent an email to Dirk (the FSBUS "Daddy") about this.The Stab trim wheels are easier I guess - no physical end positions... Just cutting power to the motorcontroller (with the Stab trim switch on the TQ) when in maual. Planning on using a separate servo motor for the trim wheel scale on the TQ.If only there was a built in function (feedback from the stepper motor) updating the step no. in the Amtel when moved manually!Thanks again.Regards,Ole J. Almenningenhttp://www.737cockpit.nohttp://www.simbuild.com

I think, the best solution is to use DC motors...Look this video of a throttle quadrant & trims with motors.http://www.opencockpits.com/modules.php?na...p=getit&lid=188Look this tutorial for buildhttp://www.opencockpits.com/modules.php?na...p=getit&lid=229http://www.opencockpits.com/modules/copper...al_IMGP0129.JPGThe solution is based in SIOC and a easy IOCard circuit.