View Full Version : Pivot Point For 2DOF Platform

03-31-2007, 10:32 AM
Hi CW and all the rest of the flight crew .. Been welding the frame for my 2DOF Platform Based on Ideas from borrowed from Both Jim and Craig so lets call it a Hybrid :-) any way thought i'd ask the question regarding distance from the center of the Universal joint to pulley attachment point, as it were which would give me 20 of Movement on both roll and Pitch axises.. my steering rack has a maximum travel of approximatly 100mm so i figured that when centered and flying level i will only have 50mm of travel left/right ..front / back to achive the 20 angles. based on trig i would seem that i need the anchor point for rotation to be 138mm from the center of the Pivo Point ( Universal Joint ) May or may not be a problem but i seem to recall Craig mentioning the fact that the sim will be more responsive the closer if i connect at this point ( 138mm ) downside i means more load on the actuation system ( steering rack/Wipermotor ) as he has now moved his pivot point a lot further away thereby easing the load on the actuator did he have to sacrifice some of the angle of movement or have i missed something that would allow my 50mm of movment to give me the same angle if i moved the anchor point further away .. Major head scratching going on is it something in the pulley system Help please :-)

03-31-2007, 05:30 PM
Gidday Kelvin, I copied this from an earlier post. bearing in mind my mass with two pilots was over 300 kilos and I think my movement was down to about 15 degrees with this setup.

"my roll axis pivot from centre (each side) is 530 and pitch is about 580, these are based on the gears ability to lift the mass happily without the P/S pump going. I can (and did ) speed it all up by moving the pivots in, but I felt sick, so I guessed this wasnt right, the angles are between 18 and 20 degrees pitch and roll and it takes about three seconds to move from centre to full and about 7 seconds back to centre on washout, the rack movement is about 140 mm. One thing I have observed (IMO)is that the speed of the sim is less important than the movement (say roll) acceleration. In other words if the plane is increasing or decreasing bank the sim should be moving and it would appear that speed really plays a small part in the sensation (to a point)"

04-02-2007, 08:00 AM
HI Craig
Glad to see your still hanging around here from time to time ... Thanks as always for the info My cockpit will only be 1000mm wide by 1600mm long x 1300mm High and is a Single person setup .. Hanger was original designed to house my CNC Router various other bits and the sim, on paper it looked bigger ! Either that or i have more jumk than i thought LOL:-) Like i said i welded the beginings of the frame up and am now working at mountong the steering racks in place . At the moment i have one Regular Steering rack similar to yours and one Steering Box A la Jims Origianl idea ( See I Told you it was a hybrid ) basically i will use the opertunity to test both actuators side by side ( and hoping the speed controller will even things out movment differential wise ) .. Photos coming soon Promise .. Will stick with the 137mm from center pivot point and see how the units perform with my load .. aiming for just under 200Kg all up weight inc the lard arsed pilot Me but dont quote me on that things change .. Cheers again Craig .still check your site and jims everyday you guys set the standard i just follow :-)