UPDATE 22nd Oct 08 - BFF Motion Driver V1.6.5d now available for FS9/FSX. This is an important update and should be used in preference to previous versions.

UPDATE 18th Nov 08 - v1.7beta is now available for FS9/FSX which introduces LAN networked operation - see downloads page.

The Motion Drive Software is a key part of any motion platform system. It handles the real-time extraction of flight data from the flight simulator and the calculation of motion cues for the cockpit for export to the Signal Processor Unit or other external control hardware. The primary output of the motion software is position demand cues for the platform. These are then used as inputs to position-feedback (servo) control hardware to drive the platform movements.

The drive software originally used two free FS utilities to obtain the flight data from fs9, one was Keith Daniel's PortDrvr gauge utility and the other Russ Dirk's FSConnect module. The current full release version of the software for FS9/FSX uses Pete Dowsons FSUIPC alone to obtain motion data and gives data update rates of about 25 sets per second (possibly faster on FSX). This refresh rate results in smooth cockpit motion and less noticeable movement delay between visual events on screen and associated movements of the cockpit. The normal configuration is to run with a single COM port serial output to the drive hardware. It runs on the same PC as the flight simulator and doesn't affect frame rates much at all.

The X-Plane version utilizes X-Planes' built-in data output facilities and communicates with the simulator using UDP protocols and can be run on the same machine or over a network. The forthcoming Falcon 4.0 version will communicate using that sim's shared memory area.

 

The driver now comes with two separate setup programs which allow a wide range of user configurations to be made for different types of motion platform in addition to control system setup functions.

FEATURES of this VERY LOW COST software:

 

Versions compatible with FS9/FSX and X-Plane 8.6 & 9.2.

 

Motion Cue outputs for 3 DOF platforms with independent DOF actuation and for 3 point support platforms.

 

Alternative data output modes - Binary (for use with the BFF SPU) HEX2 for general use and Shared Memory for direct inter-process data transfer to other applications.

 

MSFS version come with PID Servo Control software to simplify the external hardware design.

 

Highly configurable cue settings with separate set-up program and multiple file saves. 

 

Cue data text output for charting & inspection.

 

Selected aircraft status indicator outputs.

 

Detailed User Manual

 

As of v1.6 of the FS9/FSX driver a new PID Servo Controller application is included which performs control loop calculations on the PC that were previously done by the external control hardware. This substantially simplifies the external hardware and offers better control algorithms - see here.

The motion drive software has a simple user interface which gives a real-time visual monitor of the motion cue outputs and program status.

The movement cues are derived from aircraft accelerations and orientation. I've used classical filtering and washout algorithms (cf this Masters Thesis) to develop force cues. Platform pitch angle is derived from the instantaneous aircraft fore/aft acceleration and pitch angle with an element of pitch-rate cuing. Roll angle is derived from sideways acceleration with an element of roll angle to simulate felt roll rates. There is therefore a strong element of "gravity alignment" or "tilt coordination" in the pitch and roll DOF's to simulate the force effects of acceleration and orientation, although the strengths of the effects can be user adjusted.

The heave cue is the most complex and is derived from aircraft heave acceleration. The limited cockpit heave movement makes heave motion cueing less than straightforward. Cueing sustained acceleration events isn't possible with a short stroke length so only the on-set and off-set of these events can really be cued and making these short acceleration "impulses" feel right with the simulator visuals and control events is quite challenging. This is done by noise filtering, limiting and washing-out the aircraft acceleration to catch only the start and end of sustained acceleration events. The heave motion is further complicated by the general behaviour of the type of aircraft being simulated. For example light GA type aircraft flown in a controlled way don't see levels of acceleration that are all that high - indeed any flight turbulence there may be can quite easily swamp the manoeuvring G's. So an effective use of the heave movement in the motion cockpit seems to be to simulate ongoing heave activity due to flight turbulence and also to simulate what can be quite active movements during the higher speed runway operations.

There is a detailed User Manual which describes the program setup and use - see the cockpit downloads page. From this you can see that many of the parameters used to control the motion cues are adjustable by the user.

Another issue related to heave motion cueing is that quite often FS9 reports flat-calm flying conditions and unrealistic zero heave movement even in light aircraft which you might expect to bob about quite a bit. Similarly on smooth runway types there is very little heave movement reported even though take off and landing runway activity should be quite dynamic. To make these events more realistic I've built-in a heave motion recording facility which allows you to record a 2 minute long spell of heave activity from FS9 for the aircraft normally used. This can be used to record straight and level flight motion with no effects present other than light or medium turbulence effects and can later be switched on or off in flight to suit personal preference when the actual flight conditions seem too flat. The same recorded data can be used to produce dynamic runway effects by increasing the frequency of its playback and scaling the movement amplitude according to ground speed. The need for this in X-Plane is less pressing as its flight model seems to produce much more movement during normal flight.

The business of fine tuning the motion cue algorithms can be undertaken by the user though adjusting the parameters in the software's configuration files. This can be done manually or using the Driver Setup program which provides a more user friendly interface.

Software Set Up

See the Downloads page .

 

 

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