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Motion Platform Power Calculator

Motion Platform Power Calculator

 3-DOF Motion Platform Power Calculator Model & Software

Motion Platform Power Calculator


Download .zip package here

(Requires BFF Motion Driver v2.4 or later. Install the calculator software in its own directory - not in the motion driver directory. Will run with demo driver.)

ADDED - June '09 - Actuator Power Calculator


I've been asked many times for help by builders trying to work out how big drive motors need to be for their DIY motion platforms - and haven't really been able to give a good answer because of the complexity of the problem and the time it takes to do the calculations properly. I've written a small piece of software which might help (or simply serve to confuse further?) as an add-on to the BFF Motion Driver. It provides power estimates for conventional 2 or 3 DOF motion platform types - those with 2 or 3 actuators below the platform and a central column/spring.


The software runs a real-time simulation of the defined motion platform to which it applies drive actuator displacements to generate platform velocities and accelerations. From these the equations of motion are solved to calculate actuator forces and from these powers can be determined. The actuator displacements come from either the "live" outputs from the BFF Motion Driver (running in Mode=MEM config) or from sine wave displacements generated internally by the power calculator software.


In both cases the BFF Motion Driver v2.4 (or later)software must be running on the PC. The calculator will operate with locked versions of the motion driver, but it will stop when the Driver's demo time elapses.


The estimated required power ratings of drive motors are obtained by capturing the maximum actuator force and speed events that occur across all actuators during the period of motion.


The Power Calculator can be used to experiment with different platform dimensions, loads and states of imbalance. The sine wave actuator displacements can be applied to different DOF's, eg to heave only or to pitch only, and with different amplitudes and frequencies to let you see the effects on actuator forces, speeds and power of different regular wave motions. The idealised actuator duty arising from actual flights and motion driver configurations can be looked into. It is also possible to use the Power Calculator to inspect static actuator loads by manually adjusting the actuator displacements using the "Manual Override" feature of the Motion Driver.


Motion Platform Power CalculatorThe most useful way I've found of using the software is to run the platform model with a fairly demanding sine wave motion input to assess power requirements and then to check those ratings against the duty arising from simulated flights in bad weather or in which sharp manoeuvres are made. It is also fascinating to watch the effect of moving the platform out of load balance by shifting the COG away from the pivot point - the actuator loadings increase substantially and the power requirements can rise sharply.





It is IMPORTANT to note that the software is at a beta state and may have bugs. Note also that the results should be used as design ESTIMATES and should not be used as the basis for design decisions without independent benchmarking by other means. The mathematical model used is a bit more sophisticated than the usual long-hand calculations but it is still a simplification of the real physical system. The numerical methods used in the simulation also will introduce the odd glitch or spike into the force results and will reduce the accuracy of the results at higher frequency motions - accelerations in motions faster than roughly 4-5Hz will not be calculated reliably due to the refresh speeds of the motion driver and the calculator software. This means that calculated power requirements for vibration type motions will not be reliable.


The results accuracy will also reduce with larger pitch and roll angles - the model is intended for platforms with "normal" ranges of pitch and roll movement - say up to about +/- 45 degrees.


If you want to use the software please read the User Manual carefully before doing so and use the results intelligently. Please report any bugs you might find.






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