Here is a jumble of emails and forum posts, I am too lazy to write everything out so I have just cut and pasted any stuff that may be of relevance!
Gidday, enclosed is some info, I probably need to explain the way I have done it, I havent laid out my stuff like Jim does because it would just be doubling up. My wiring is different but achieves the same result. I use K74 parallel port interface with 8 relays and I supply a common power to them. the K74 has the ULN 2803a IC in it. I am assuming you have all that but let me know if you want the stuff on that. I use relay 1&2 for pitch 3&4 for roll 5&6 for brake and accel which just piggy back onto the 1&2 pitch relays. The 3rd limit switch I use to stop the sim moving right back on accel, relay 6 turns on the limit relay and brings the 3rd limit micro switch (which is mounted closer to the centre) into play there fore on accel the sim comes back then at about 80 knots the 1& 2 relays start to work and at rotate, relay 6 (accel) goes off voiding microswitch 3 and the sim moves back further. With the dicksmith 3072 I have taken VR1 out and put a double relay to operate 2 10K pots it is fed from a 'fast' power supply so that I can control movement speed,there must be a millisecond where as the relays switch over it turn off and resets 3072 so the return to centre can be controlled by the other pot. Have fun mulling that over, I spent hours looking at Jims diagrams and working it out, feel free to ask questions via this email address Cheers
Gidday, I used two steering racks one for roll and one for pitch. (2 DOF) With the wiper motors connected, it eliminates any back pressure, you can literally jump up and down on the platform and not move it, I used cables because on the problem of transferring horizontal movement (racks) to vertical (platform) and it seems to work ok. Although I copied Jims concept I made quite a few wiring changes due to me not needing to soft start. anyone interested in details of the rig, email me.
Gidday, I have 4 mm stainless cable with an eye hook on one end. The pulleys started out as 38 mm die cast from the local hardware store and I just replaced the pin with a bolt, however the mounting point was weak and I replaced them all with 50mm steel ones and secured everything firmer. Good idea about the 90 degrees, I mounted mine as I did because I thought that the width of the rack compared to the platform may have been and issue. I cant (in hindsight) see any disadvantages and several advantage to mounting the racks 90 degrees and should of probably carried on with that plan. I also only used cables because I was lacking in ideas to send the motion from the horizontal rack to the vertical platform, I was originally going to mount the whole lot in a cradle and raise the COG but cost and time got in the way. But as it happens the extra pulleys dont affect the performance at all and it works fine. The push pull may be OK. I only used one end of the rack and made a plate with a hole in it which fitted in where the inner tie rod end is and cut off the tie rods. My only comment is that the strain on all the mechanical parts, cable, mounts, pulleys etc, is very high and took me by surprise, please over-engineer everything connected to the motion to avoid not only breakages but everything stretching and moving. Happy building!
Gidday, I think it may be due to the hydrualics softening the start, however it is early days, and to be honest I may still have to go down that road, I am using resistors at the minute for washout, with a few issues, but generally I have a reasonable feel so far and I am in the software/hardware tweaking and tuning stage now, will keep you updated! Happy motions! Edit/Delete Message
The return to centre, you are right, when 1 becomes 0 or when the aircraft hasnt changed roll angle, my roll relay switches off and allows the return to centre relay to take over and allow the motor to move in the opposite direction until the centre microswitch stops it all, in other words the platform will always want to be in the centre unless the PC has other ideas by sending a roll signal. I have my soft start wired up so that the power that makes the sim R.T.C (washout) also changes (via a relay) the pot VR1 on the softstart unit.Therefore with 3x 5K pots and two DPDT relays I can control the activation speed and RTC in either direction (Made for that fat co-pilot) or only me on one side of the sim.I set the speed of washout so it is slow enough that the brain doesnt notice it, the only unfixable problem I have is that there is no 'soft stop' and you can feel when the sim stops moving. I deal with pitch a bit different and have wired in a return to centre inhibitor to stop RTC over a certain pitch angle, I feel that on climb or steep dive you should be 'back in your seat' or 'hanging by your seatbelt', I am still experimenting on the proper angle I am on 13 degrees down and 10 up at the minute anything under that the platform will return.I like the idea of not returning completely to centre but with no feedback I cant really impliment that, I now would like an interface that is more than 8 bit, I am fast running out of channels to use as ideas come to mind. I reackon I have probably halved the sim speed since it was first run, the brain pick up the movement just the same and it is more controllable, I also am not getting airsick any more, that I feel is a good indication that the motion cues are what my eyes expect to see. Cheers.
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) hope that helps, Cheers.
Unfortuanately have no data
on my racks (Mazda astina, nissan Primera) I will get back to you with
number of turns and throw distance actually I know the throw distance,
its 140 mm. I never intended to use the setup with no power so I did a
tim the toolman, "need power
Gidday, I fitted my softstarts and worked out a way that I am only using 1 per axis, works bloody well I am glad I went down that path finally. used three pots connected to 2 dpdt relays to change the speed from 'moving there' and 'moving back' and 'moving back from the other way' to compensate for weight differences for and aft, left and right seems ok, going to mount it inside to add to the switch and panel effects, Cheers, have a productive week! (Sim not work!)