New build noob questions

Hi all,

I'm new here and just 3 weeks into gaming. Caught the bug after years of resisting anything gaming related. I blame rFactor 2 for that, but then again, rF2 is more than just a game - to me at least.

I'm diving in and will try to build a simulator. These are my questions so far, if you please:

- When you start the simulator, is the seat positioned at the middle of the travel range so it can move back and forth or does it start at the bottom/top and move from there?

- How much travel is typically needed?

- Anyone using non-worm drives (ie: planetary, inline), even if it's less efficient?

- I take it only the seat should move, as trying to move the entire rig would require much longer throws for same level of effect, correct?

- As per above, how important is to have the monitor mounted to the rig so it moves with it?

- How much is a "traction loss" axis really needed? Does it add a substantial amount to the simulation experience?

- Anyone using reclining seats instead of solid shell ones?

- Is there a standard protocol from games, etc to provide movement data?

- If above is true, is this an industry standard that others adopt, for example, movie publishers?

Regards,
JR

Hello and welcome, Tao try to answer your questions,
The seat is at best balance point for a 2DOF and it does move back and forth , side to side. Have a look at some videos of the projects here.
You do not need much throw as it's a mind trick, so no need for a rig to fly 300mm up from centre , although some will disagree , and it's simpler to set up a smaller throw and you still get the desired effect.
Non worm drives , nothing that I know of apart from a boat winch motor . Worm drives are relatively cheap.
Usually best not to mount the screen with the rig as with car driving , you keep your eyes on a Fixed point on the horizon. That and motion will eventually damage the screen. Flight it's good to have a screen moving with you.
Traction loss will add the the effect, but start witha simple 2dof to get used to setting up And writing a profile is suggested.
Yes I use a recliner and have on previous builds. It has some side support and does well? A bucket seat can be found cheap .
Standard protocol? Not sure what you mean, but I suspect it's whatever data we can get from the game for motion
While I think of it, for motor control, the Pololu JRK for sure , one per motor , excellent resolution and motion quality , simple to set up. Money well worth being spent.
Industry standard , dunno.
Cheers David

Thank you David.
Ok I will start with 150mm total throw and see how that works. I can see how not all of that will be strictly vertical movement so I'll play with that if needed.

I asked about worm drives because I have a few wheelchair motors that are robust and have continuous rating, but are not worm driven. That means some energy will be used to keep the seat locked in a position. That should be fine though as I've used these motors to make a clone Segway that balances the rider's weight and they work great for that.

Good to know I can use recliners since they are relatively cheap and plentiful on eBay. I was worried the shoulder mounted actuator would shred the seat's reclining parts to pieces. I'm also a tall and fat guy so being able to recline the seat to my liking before settling on a comfortable position is important.

I ordered a RoboClaw motor controller as I've used them in the past. I now see that I will miss out on the JRK software to control the whole thing, we'll see how that goes.

The protocol question was to know if there's a defined stream of data that I would have to read, interpret and use to command the motors. I suppose that is less important if I were using JRK controllers but I'm guessing there will be some coding in my future to send the game data to the motors.

Regards,
JR

Hello JRoque!

Nice project
You may find some valuable information in this thread about Roboclaw roboclaw-motor-controller-investigation
how its PID works, why it may be not the most appropriate, how it may communicate

And I thank you if you can share your knowledge about Roboclaw

To answer some of your questions:
- Anyone using reclining seats instead of solid shell ones?
if you became game addict playing for hours, reclining seat may be a good point! +1 for me
The drawback is weight but if you're using strong winch motors, or building a frex-like seat mover, weight won't be the main concern.

- Is there a standard protocol from games, etc to provide movement data?
Yes, please read the documentation http://www.xsimulator.net/simtools-complete-documentation/
look for "Game Manager"

yours
Mat

One point not noted on using a reclining seat , that as you lean them back causes the cg point(which is one the most important facts) to become more and more rear heavy, And a std seat mover from doesn't allow for this as the rear bar need to be rigid as possible as any flex there will result in a loss of motion and a very sloppy feel.
The cg is important in creating a responsive seat mover get it wrong will result in different speeds caused by it either being front heavy or rear heavy as in the motors are now not evenly lifting and dropping. I see this mistake a lot.


RoboClaw beware the serial communication with SimTools is totally untested but you might strike it lucky with previous experience and get them running fine, plenty of people here that can offer guidance, but none have actually achieved a sim with this driver.
So please be our pioneer and show us all how to do it, Thanks.

Yes we have a std protocol on what a game produces , well we export the raw roll,pitch,yaw,surge,sway,heave to the Game Engine to produce a motion cue. Some games don't give all 6 DOForces so their we try to at least supply Roll ,Pitch, Yaw.

Also you will find 150mm of movement to be way to extreme for a racing simulator but with clever profiling of the Axis Assignments for the racing games (as in using less of the % of the Axis) will result in nice sharp racing movement but also allowing you to use the full 150mm for flight games where the extra movement will be a plus.

So far all looks good, a lot of work to go, good luck and please don't hesitate to ask questions.

well ,my recliner seat actually is positioned to my liking and sits against the t-bar, so the balance point is set.
The roboclaw sounds good and if you get it running, for sure it will be good.
Wheelchair motors should be fine as well.

Hi all and thanks for the help so far.

I'm still another week or so before I have my RoboClaw but looking at some of the documentation, it would seem they do support positioning when using a pot. They say "Analog feedback is also supported for closed-loop position control". On page 61 of their user's manual they show the commands needed to position the motor using potentiometers. We'll see what I get when the board arrives.

One thing's for sure, my goal is to build the sim as quickly as possible so if I can't figure out the RoboClaw board quick enough, I'll buy what works and leave the R&D for another day.

On the seat reclining part, I plan to adjust it to where it's comfortable and never move it from there. In fact, if I find a way to brace it from the sides I would do that.

Regards,
JR

Building a sim needs a lot of skill and time. The guys here will support you in your project but everybody hopes you will figure out the robo claw working

Hi there.

Deal. I will try since I already invested in the RoboClaw.

Quick question on the darn seat: cloth or fake leather? There has to be thousands of different seats on eBay. I have it narrowed to a few that look nice (to me). But they come in cloth or what they call "PVC leather". I can guess that leather will be cooler (temp) but cloth might grip better. What's your take?

I'm in the process of modeling the frame, seat, etc. To my surprise, I found 3D models of a racing seat and a complete Logitech steering wheel, pedals and shifter. All of these are free, downloadable in many formats and available after registration at: http://3dcontentcentral.com. I have used them for years and if you're ok with getting some spam from them, there's a lot of free and useful models there.

Regards,
JR

Modelling is nice, but probably not necessary for something as simple as a seat mover, just don't get so wrapped up in the modeling that you never build anything , although I see you have built a Segway, so most of the build should be easy for you. Re Seat, if you are going for a recliner, I would pick cloth over PVC leather for the reasons you stated.

I would prefer cloth if you intend to spend a bit of time in the seat, Mine fake leather on a hard plastic seat, no that comfortable specially in summer months, but allows me to feel every bump and seat absorbs nothing. But we all like to race differently.

Modeling, can be handy and if you look through the posts there is one showing how you can link simtools with the model and have it move as if it was the real thing, This can be handy in designing. But as @SeatTime has suggested, I just get into and build and draw up what actually worked so I may share it with others. But I have built a few over the years, my last seatmover was slapped together in hour to show how cheap and easy a seat mover can be and how easy it can adapt to a static sim , most sim racers already have.

Hi all,

A brief update: the RoboClaw manufacturer responded to my question and they confirm that a potentiometer can be used as a positioning encoder. He warns that the resolution will be lesser than when using a 2048-bit optical encoder

It'll be a week or two before I get my board and can test the theory. But with that confirmation, I think it's save to say it can be done.

JR

That's encouraging! I think they mean up to 11bits with 2048ppr optical encoders but I'm not sure. If they said less with a pot then it may only have a 10bit adc on it. I believe you control the roboclaw with 32bit numbers thou. I guess they answered your questions directly and not on the forum as they suggest because I didn't see it there. Anyway, did you get information from them on how to use a potentiometer with 32bit numbers to set a desired position? Is 2147483648 equal to center position? If so SimTools may need a modification to work with more than 16bits. Thanks.

Hi. Yes, sorry, fingers were quicker than brain. I meant 2048 PPR. I happen to be working on 2048-bit keys for my day job and got my wires crossed.

But to the resolution end, the RoboClaw has a 0 to 2V ADC input range. It is 12-bit resolution but at a 2V span there isn't much room for pot errors. I suppose we could front-end their ADC with a some sort of scaler so the pot can travel between 0 and 5V, but now we're getting into building external supporting circuitry that might complicate things.

BTW, just ordered a few 180 deg hall-effect pots. I plan to attach them directly to the motor shaft. I'm a bit worried about hysteresis and overshoot knowing I have only 180 degrees of travel at 0 to 2V range. Then again, others have managed to make their gear motors work with <180 movements.

JR

You need less than 180° : close to 180° the vertical speed is null...
https://www.desmos.com/calculator/8l2kvyivqo
(in french but more usefull for calcultion http://www.mecamedia.info/index/flash_biellemanivellev3 )

keep us informed about roboclaw, thanks!

Hi JRoque , At 12bits is good news! But if its resolution is less than a 2048ppr encoder, and a pot turns one revolution also, then it still appears to me to be effective to less than 11bits. I have been concerned about the 0 to 2 volt range also. But I think you will need to use a standard pot unless you already have a plan to deal with the hall effect pots that must be powered with a minimum of 4.5 volts. But really they need at least 5 or they drift more. You may be able to use a voltage divider circuit though to lower them to the proper range.

Hello all. I just wanted to circle back and close on this thread. I was challenged to make the RoboClaw controller work without using an auxiliary processing from an Arduino and such. Per specs, the RoboClaw should be able to that. In practice, however, it doesn't.

First, 2 of my RoboClaws blew up during PID tuning. The tuning software is provided by the manufacturer so the failures were not caused by me. It took nearly 2 months to get my board back from repair. The last board I tried no longer connects over USB for some unknown reason.

I have full confirmation from the manufacturer that the RoboClaw can use potentiometers as positional encoders. They assure me this works but it does not. I worked on this project for months, exchanging emails and blown up boards with the manufacturer. The board does not read the pots in any usable way. The motor will simply spin forward as a slow rate.

So, just for closure, I'm moving away from trying to make the RoboClaw work standalone and will be using an Arduino-like interface to read the pot and drive the motors. The RoboClaw board itself, as a motor driver, is fine. I'm using it in another application without problems.

Regards,
JR

Thankyou for the final update on the roboclaw shame the manufactures could not come up with the final goods.
But as a motor driver only cool its all salvageable. Nice to hear that.

Thank you for information, but IMO to use the RoboClaw board itself only as a motor driver it is way too expensive. For you it is OK because you have it already. For all others keep your hands off.

Hi!

I'm not sure how much damage I got on the RoboClaw I used for these tests. For sure, the USB port no longer works. I hope I can still drive it using the onboard pins.

Agreed. Just for good measure, I ordered two, BTN8982TA-based controllers (eval boards, actually) and two of the Chinese "43A double" ones.

I like the specs on the new BTN8982TA chips: 55A (with higher peaks), up to 40V, low Ron, integrated drivers, current monitoring, self-protection. The eval boards I ordered are limited to ~30A due to the slim PCB traces but 30A running at 24V should do well for a sim - I hope.

Regards,
JR