Force with rc-servos

Hello

I am new on this forum (Norwegian) and I am dreaming about some force feedback to my racing game (GTR2 - rFactor). I have read about Chewes ForceStick He is using serial servo controller and rc-servos to add force to a helmet using x-sim. I have limited knowledge about electronics and programing, and I want to start with some simpel way to get force feedback. I wonder if several rc-servos controlled by The Pololu serial 8-servo controller (or similar) would be enough to add som force movements to a diy racing chair? (not real g-force) If anyone have a better idea that is not to adwanced (or exspensive) I will be very happy. Hope to get som (force) feedback to this. I do have the DIY-spirit but Tronic`s diy elektronics is to adwanced for me to build.

Anyway a very interesting forum!

Fred

Rc servos and torque:
I have searched a little bit more: Pololu offers 6v servos with torque up to 24kg-cm. I do not know how much torque that realy is. Does anyone know how much torque there is in viper-motors used in simulators presented here at the forum? I am also wondering if several servos connected paralell will give more power. An exampel: 2 sets of four 24kg servos (y-axis an x-axis) and pololu 8 servo controller, could that give enough force? Theoretically this vill be 2 times 86 kg torque,,,hm!!! I am just thinking loudly, so if you are tempted to laug out loud of my ideas, you are velkome
(Language: Norwenglish)

Fred

24kg-cm is around 2,5 Nm , viber motor has around 4 Nm (you can see some types here http://www.opis.cz/nidec/snek24V.html ) but 2,5 Nm for servo is peak torque but wiper motor could have stall torque 10x more than continous (look at n/M/I grafs )

Thank you for the respons. Can you explain the differens between stalk, peak and continious, an what do you think is the most important in a simulator? (Did not understand the graf`s)

Fred

I dont write it wery well .Stall torq. is how mutch torq. you have to apply to stop motor, than you have continuous and peak, you can have cont. stall torq. (for long time you dont burn motor) and peak stall torq. (for short time or you will burn it). For example DC servo (not RC servo) will have 0,2 Nm cont. and 2 Nm peak so you can overload motor to 2 Nm and with faster RPM moment will fall down. So wipers motors has for example 4Nm (in nominal RPM) but to stop them and hold you will need 24 Nm. RC servo have 2,5 Nm but that is for stall so if servo rotate it has mutch less torq.

on this picture you can see curves for 8Nm (at 70 rpm) wiper motor, you can see (line n ) as rpm is go down torq. bigger (unil dash line (48Nm) its cont. but after that its peak).

Ok I maybe understand it a little better. Does it mean that using rc servos here is a bad idea? Will they easily get burned? The reason I am thinking about using them is because it looks like the way Chewe http://www.x-simulator.de/forum/forcestick-diy-55-2-dof-motion-simulator-t1056.html used them was easy and cheap to build. For a start I dont need fully g-force experience, but it could be fun to add some force feedback. A little force is better than no force, but I would not be comfortable sitting in the livingrom with a helmet on, so it would be better to get some movement into the chair.

Fred

For your head is servo enought (whiper motors could hurt you ) but for moving whole seat it is not.

I do understand this will not work on the sim chair constructions presented here on x-sim. I might try to find a way to construct a chair that nedd less amount of torque to move. the joyrider seem to be very balanced, but I guess it ned some torque to move anyway. This need som thinking... :? If the position of the chair is stable after moving, and the servo is not holding the veight of the chair it might be posible??? At home I have a rocking chair...This type of chair need small amount of force to move, so maybe I can adapt some principles from that ;D

If you dont have center of gravity exatly in axe of rotation you will need some force to hold it, for move your sim you will need every time some force. Rocking chair need lot of torq to move. (force is small becouse it has big lever)

I belive a cant build simulator without some torque/force, but it could be interesting to find a construction that needs a small amount of force. It is maybe dificult to build something with exact senter of gravity in axe of rotation, but its a challenge to try to find a way to do it. diy is about challenges, right?? But it might be easyer to find a way building it with viper motors..!

Fred

For example Joyraider is close to ideal, but its simple and cheaper to buy proper motors

I could buy viper motors, i might even have some laying around, but the big challenge for me will be to make them to be servos that can work with x-sim! :?

Just bulid this tronic-s-amc-motor-motion-controller-with-pwm-servo-output-t559.html and this tronic-s-diy-dual-mosfet-h-bridge-dsmhb-t820.html and you can control wiper motor wery well. If you dont understand electronic, learn it or start make money and pay someone to buildit for you

Maybe that is a good advice, and maybe it is not so advanced as it seems!?. I might try to investegate this a little more in sparetime betveen work, kids housebuilding, and other hobbies as t.ex my wife!!! :brows:

No its not hard, its sometimes like lego

Lego !!! Then I can leave it to my son!!! He is a real Lego-master. :thbup: I did look at the board drawing and parts list. I have found tutorial for making the circuitboard on youtube http://www.youtube.com/watch?v=wKEe3otW ... re=related Is this a method that can be used ...en in northern parts of Norway! :yes: Fred