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Post by morashidi on Nov 15, 2016 9:31:50 GMT
Hi all,
I recently finished my sim, it is working fine but there is one strange issue.
Let me first brief you on my sim specs:
VFD specs:
Brand: Huanyang
3HP AC 220, 50HZ/60HZ
2.2 KW 11A
Motor specs:
60 Hz 220/380 V
1.5 kW/2HP 1720/min
GearBox is 80/1 ratio
I am using BFF software to drive the sim.
Now the issue is that for heave move when the sim is going up it moves smoothly without issues, however when it moves down it looks
like it vibrates; it does not move smoothly.
Here are videos showing the issue, I moving the sim up and down using AMC1280USB board
Video 1:
And here is a video showing my friend playing Asset Corsa (using BFF software):
Really appreciate your help.
Best regards,
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Post by morashidi on Nov 18, 2016 8:58:47 GMT
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Post by morashidi on Nov 21, 2016 4:47:59 GMT
I tried the suggestions mentioned in that topic but it did not solve the issue :-(
Could it be the gearbox size I am using?
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Post by clyevo on Dec 7, 2016 11:28:53 GMT
my thoughts is
1. the inverter torque control is not very good. It is not reading the inertia of the load and overshoots. Most guys here uses hitachi brand. So if you have the money maybe try one inverter. (probably wait for a better solution and views from other members before trying this)
2. check if the movement of your 6dof model is not restrictive mechanically. Check for unequal arm length and your hexagon cockpit is in perfect symmetry.
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Post by morashidi on Dec 10, 2016 16:05:02 GMT
Thanks for your help
I don't think it is due to unequal arm length nor to hexagon cockpit symmetry; because when I move only one arm the issue happens also.
Here is a video showing moving one arm
After several readings and thinking I decided to attach spring to one arm and test it, here is the result the issue does not happen !!
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Post by morashidi on Dec 10, 2016 16:11:44 GMT
I will look more at VFD settings and check torque control parameters, I might find something useful.
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Dec 10, 2016 22:17:33 GMT
I will look more at VFD settings and check torque control parameters, I might find something useful. This is quite similiar to what i have been experiencing. First of all I am no way expert, rather willing to share my experience. Here are my thoughts. 1. There is backlash in the system. There has to be, otherwise the wormgear can not work. But the level is important, if it is too much then it is difficult to manage. So try to minimize it. I changed my reductors and welded some of the loose parts for that purpose. 2. The tremmer/vibration you are experiencing is happening when system moves with the direction of the gravity(1 G)(or any existing acceleration). If your ramp settings are too fast, system may look like moving one direction smoothly but the motion commands may come in pulses of higher acceleration. In That case gear box starts moving ( +1G) and when the motion command pulse stops, gear keeps on moving until it reaches to the end of the backlash. Then it starts movings with the following motion command pulse. This creates the vibration and if your system has more loose parts then the vibration increases. 3. When you connect the springs, they pull the arms even when they are moving down. This way the arms stop as soon as pulse stops. The gear never moves in the backlash. 4. Even with the minimum backlash, ramp type, ramp time and delay settings shall be tuned in order to avoid vibration. 5. I could stop the vibration on my platform when going down just by tuning the ramp times. But when the platform moves faster I still have vibration because of the backlash. I am still working on that. I will also try the spring solution. What kind of springs you have used? Where did you obtain them? Good luck
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Post by morashidi on Dec 12, 2016 11:33:13 GMT
I will look more at VFD settings and check torque control parameters, I might find something useful. What kind of springs you have used? Where did you obtain them? I went to one of the local stores specialized in selling all different types springs, unfortunately I could not find ready made ones that fit my specs. I had to ask them to manufacture springs based on my specs which is more expensive than buying ready made ones. I did a lot of readings about spring, how they work and how to select the right one. It was a good learning curve. There is spring calculator tool which was helpful to me: www.acxesspring.com/spring-calculator.htmlBased on your requirements you have to decide on spring length, safe travel, wire diameter, outer diameter, no. of coils...etc it is tricky I had one failed try then the second one seems to work now.
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Post by tronicgr on Dec 12, 2016 11:51:26 GMT
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gokhan
Junior Member
Posts: 89
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Post by gokhan on Dec 12, 2016 18:33:12 GMT
What kind of springs you have used? Where did you obtain them? I went to one of the local stores specialized in selling all different types springs, unfortunately I could not find ready made ones that fit my specs. I had to ask them to manufacture springs based on my specs which is more expensive than buying ready made ones. I did a lot of readings about spring, how they work and how to select the right one. It was a good learning curve. There is spring calculator tool which was helpful to me: www.acxesspring.com/spring-calculator.htmlBased on your requirements you have to decide on spring length, safe travel, wire diameter, outer diameter, no. of coils...etc it is tricky I had one failed try then the second one seems to work now. It also worked with my case. My platform is around 150 kg. With the pilot it weighs around 220-270kg. Per actuator 25-50kg. should be enough. I got springs from 3mm diameter wire, 25 mm spring diameter and 350 mm unloaded length. Giving roughly 29 kg when fully stretched. I tried them this afternoon and they really smoothened the downwards motion. Though the backlash still becomes effective when accelerating to any unloaded direction. Thanks for this valuable advice. Here is the picture of my setting.
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