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Diy Load Cell Brake


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#1 jklhill

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Posted Mar 12 2012 - 09:36 PM

I have always wanted to try a load cell brake but they are way too expensive for my budget. I would just like the realism of shorter travel and more feel. And, yes, I have already stuffed various things behind my pedal to try and achieve these ends but there is only so much you can do with a pot. Then I stumbled on these tonight. http://www.trossenro...ce-sensor.aspx. The price is right but resistance is not linear with force (see page 8 here http://www.trossenro...eUserManual.pdf). I'd really appreciate input from the collective wisdom represented here. What do you think?

Thanks, Larry

#2 Paddy the Irishman

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Posted Mar 13 2012 - 07:55 AM

It looks very interesting indeed,  Could be installed between pedal and stop, epoxying a small circular 'knob' on the underside of the pedal arm.......

I don't thnk that you would need a linear response, that is not what you get with a real brake pedal and so I think that the curve shown might not be too bad.  Think with youir foot !

However, it is my understanding that braking effect in sim-world is DECREASED by an INCREASE in resistance, so some type of circuit would need to be introduced to 'reverse' the effect. I expect that this has had to be done in all load-cell brakes, so someone here should be able to help !

Perhaps someone could work out and draw up a circuit for us ?

PLEASE keep us all informed  :thumbup:

#3 jklhill

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Posted Mar 13 2012 - 01:39 PM

View PostPaddy the Irishman, on Mar 13 2012 - 07:55 AM, said:

However, it is my understanding that braking effect in sim-world is DECREASED by an INCREASE in resistance, so some type of circuit would need to be introduced to 'reverse' the effect.

I have a Logitech wheel and I think this can be done in the Logitech Profiler software. DXTweak might also might also be able to do this, I'll have to look when I get home tonight.

#4 DRat

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Posted Mar 14 2012 - 07:04 PM

You might want to look at the APelectrix.com load cell brake for the G25/G27.  It was just $75 USD plus shipping but was an easy conversion.  It works great with all sims, and yes, I also use the Logitech profiler to reverse the polarity of the brake - it works very well also with all sims.

#5 jklhill

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Posted Mar 14 2012 - 09:48 PM

View PostDRat, on Mar 14 2012 - 07:04 PM, said:

You might want to look at the APelectrix.com load cell brake for the G25/G27.  It was just $75 USD plus shipping but was an easy conversion.  It works great with all sims, and yes, I also use the Logitech profiler to reverse the polarity of the brake - it works very well also with all sims.

Andy's load cell is what got me looking for a load cell I could configure myself. His unit looks like it is a quality piece but I would still need to adapt it to my pedals. I should be able to do the FlexiForce Force Sensor for about $30.00.

#6 Paddy the Irishman

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Posted Mar 16 2012 - 05:46 AM

View PostPaddy the Irishman, on Mar 13 2012 - 07:55 AM, said:

I don't thnk that you would need a linear response, that is not what you get with a real brake pedal and so I think that the curve shown might not be too bad.  Think with youir foot !

However, it is my understanding that braking effect in sim-world is DECREASED by an INCREASE in resistance, so some type of circuit would need to be introduced to 'reverse' the effect. Perhaps someone could work out and draw up a circuit for us ?

PLEASE keep us all informed  :thumbup:

Re-reading the 'Trossenro' details, I see that the load cell actually DOES decrease the resistance.

As my teachers used to say,"Read the question carefully"

So again, PLEASE keep us all informed  :thumbup:

#7 jklhill

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Posted Mar 16 2012 - 10:13 AM

PLEASE keep us all informed  :thumbup:


I ordered the 8 Inch FlexiForce 0-100 lbs. Resistive Force Sensor. I should have it early next week. I will post results as soon as I have time to get it installed.

Edited by jklhill, Mar 16 2012 - 10:14 AM.


#8 voda1

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Posted Mar 29 2012 - 02:38 PM

View PostDRat, on Mar 14 2012 - 07:04 PM, said:

You might want to look at the APelectrix.com load cell brake for the G25/G27.  It was just $75 USD plus shipping but was an easy conversion.  It works great with all sims, and yes, I also use the Logitech profiler to reverse the polarity of the brake - it works very well also with all sims.

Is he still making the load cell brake? Sent in preorders from his website but never get any response.

#9 DRat

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Posted Mar 29 2012 - 05:18 PM

View Postvoda1, on Mar 29 2012 - 02:38 PM, said:

Is he still making the load cell brake? Sent in preorders from his website but never get any response.

I have had mine for nearly a year, but don't know his current status. His e-mail address is/was ajpastore@rcn.com, so you might try a direct note instead of a preorder.

#10 jklhill

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Posted Apr 02 2012 - 10:29 PM

Got the force sensor installed this past weekend and got to do about 30 laps or so. I am very pleased with the outcome. I'm going to use it as-is for a while but I think I may want to add a little more squish to the feel in the future. The pedal is really solid right now. If you've ever experienced a master cylinder that pumped up because it was setup with too little free play, you'll get the idea. Only time will tell how durable the sensor is but I don't think I will ever be able to go back to a pot.

#11 Paddy the Irishman

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Posted Apr 03 2012 - 04:38 AM

Delighted to hear how it is going.

A suggestion for 'squish', take a look at the thread 'Braking in Sims', posting 7 and pictures 3 and 4 (sorry, I do not know how to link directly).  The wedge should provide a bit of 'squish' and the velcro attachment to pedal would allow 'squish adjustment' by moving it in or out.

Two queries for you to answer please.

1 Have you just wired the load cell in place of the braking resistor - or how ?

2 You are using a 100lb cell, do you think that is the optimum value or might a 25lb one be preferable?

#12 jklhill

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Posted Apr 03 2012 - 03:34 PM

View PostPaddy the Irishman, on Apr 03 2012 - 04:38 AM, said:

Delighted to hear how it is going.

A suggestion for 'squish', take a look at the thread 'Braking in Sims', posting 7 and pictures 3 and 4 (sorry, I do not know how to link directly).  The wedge should provide a bit of 'squish' and the velcro attachment to pedal would allow 'squish adjustment' by moving it in or out.

Two queries for you to answer please.

1 Have you just wired the load cell in place of the braking resistor - or how ?

2 You are using a 100lb cell, do you think that is the optimum value or might a 25lb one be preferable?
Paddy, Thanks for the squish suggestion. I actually attached a rubber bottle stopper about 1" long, 3/8" at the sensor end and about 3/4" at the large end, between the pedal and the sensor in an attempt to get some squish. It's just not enough yet. According to the FlexiForce literature it is important to have the force perpendicular to the sensor. If there are any shear forces it will greatly reduce the life of the sensor which makes me a little concerned about going to something softer that comes into contact with the sensor. Still thinking about this one. I have some ideas but I want to keep it as simple as possible. For now I will keep driving and, who knows, my leg muscles may get used to it as it is now. I already like the feel so much better than a pot any improvement will be icing on the cake. I can try to attach a picture if anyone is interested.

To answer #1, I started out by completely eliminating the brake pot by disconnecting the yellow and blue wires from the pot and attaching them to the force sensor. This caused the brake to be about 50% applied 100% of the time and brake pedal depression would increase braking force from there. In addition, the brake and throttle would affect each other. I then went to the wiring as shown in the attachment which keeps the brake pot in the system and everything works as it should. I don't have a clue why this is so. Maybe someone who does could chime in. I am pleased that it works but it kind of drives me nuts not understanding why.

To answer #2, I'm not sure. From my observations, so far, I think either will probably work. The 25 lb sensor I think would, however, be limited as it would max out quicker or sooner. Before I ordered the sensor I sat in my homemade plywood (just so you know it's nothing fancy) cockpit and placed a bathroom scale where the brake pedal should be. I could easily press 50 lbs. The other thing is, it seems when calibrating the sensor I can set max braking wherever I desire. If I want it light, I just press lightly on the pedal when calibrating and consequently it takes light pressure to reach lockup. If I want heavy pedal force to reach lockup, when I calibrate I apply heavy force. Obviously I am still playing around to find what works best for me.

Maybe I should tell you I have the Momo Force wheel (Red) but I chucked the pedals. The pedals I am using are the first pedals I ever owned and came with a Thrustmaster Nascar Pro wheel.

Thanks again for the squish suggestion. I like what you have done with the additional pot. Great idea.

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#13 Paddy the Irishman

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Posted Apr 04 2012 - 07:55 AM

Thank you for your swift reply and the wiring diagram which I will study at leisure. I thought that you said originally that you had a Logitech wheel so I supposed that the pedals that you were using would be similar to mine.

My immediate thought on the shear problem, if there is a similarity in the pedal design, is that you could have a strip, hinged at the outer end (not on the pedal arm) that puts the load on the sensor. You could introduce the rubber 'squisher' between the pedal arm and this hinged strip, whether by the wedge method or some other.

I am only working theoretically at the moment :( because my PC is in the repair shop but plan to have a go at your idea later (if I can get the supplier to send to me in UK).

I think that I get more pleasure adding extra bits of equiment or software than I do driving - I don't crash quite so often  :D

#14 jklhill

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Posted Apr 04 2012 - 09:30 AM

View PostPaddy the Irishman, on Apr 04 2012 - 07:55 AM, said:

I think that I get more pleasure adding extra bits of equiment or software than I do driving - I don't crash quite so often  :D

:clap2: Absolutely! My wife loves to make fun of my tweaking.  :P

#15 Paddy the Irishman

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Posted Apr 04 2012 - 11:17 AM

MY wife says it keeps me out of mischief; off the streets and out of the bars  :rolleyes:   Perhaps you could sell it to your wife  :punish:  on the same basis ?

#16 jklhill

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Posted Apr 04 2012 - 11:48 AM

Here are some pictures, Paddy. I welcome your suggestions. Seems I always go for the complicated first and overlook the simple solution.

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#17 Paddy the Irishman

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Posted Apr 05 2012 - 02:58 AM

It looks very good to me.

You have have a very nice dedicated area set up, I use a table or desk for my wheel, an upright chair and the original pedal set up on the floor so any additions have to be inside the pedal box or attached to it, or else adjacent to the wheel. This is mainly why I queried the use of the 25lb load cell. I think that a 50lb might be the ideal for me but they don't make one  :unsure:
I will have to make some experiments on pedal pressure before ordering.

Having had a look at the wiring, since it is a block diagram and there are no values shown one can not be specific, but it looks to me that what you have had to do, is to put a resistor (the 'gas resistor') in between the load cell and ground ?

Edited by Paddy the Irishman, Apr 05 2012 - 03:01 AM.


#18 John Woods

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Posted Apr 05 2012 - 07:24 AM

Interesting reading here. Thanks guys.
Link to this thread added in Technical Section on www.gpllinks.org

#19 dbell84

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Posted Apr 06 2012 - 08:55 AM

Nice work jklhill.  Very interesting and informative.  :thumbup:


  For any Thrustmaster T500 users that are interested in a load cell mod, there appears to be one on the horizon.

  Bodin Load Cell mod:
  
http://www.insidesim...hp?f=151&t=6164

  
  Dave

#20 jklhill

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Posted Apr 22 2012 - 05:16 PM

Thought I should post an update.

I need to thank Paddy the Irishman for his help. The attached pictures are of the setup I am currently using for the FlexiForce sensor. The hinge was Paddy's idea. I was having trouble with my original setup (see earlier pictures) because the brake pedal has some lateral movement and that was causing some spiking of the braking forces. The sensor likes only perpendicular force and the lateral movement of my brake pedal was causing some shear force to be applied to the sensor which was causing the spiking. This, according to Tekscan, will also shorten the life of the sensor. I was talking to Paddy about it because he was interested in trying to use the FlexiForce sensor also. When he heard the problem I was having, he suggested the hinge. The button that pushes on the sensor is on the inside of the hinge and the brake pedal pushes on the hinge, not directly on the sensor. No more spiking. I am very happy with the results.

It is necessary to condition (Tekscan explains this in their FAQ's here http://www.tekscan.c...type_kb_article) and calibrate the sensor every time I fire up my computer to play GPL. I do this only once upon initially entering the game in the GPL joystick calibration screen. For me, I find a raw brake value of 160 to be about right. With this value the pedal is not too touchy but doesn't require a huge amount of force either. I also find, for me, a few numbers either side of that value make a huge difference in the pedal pressure required in the game. Without a doubt, this will depend on you individual setup. I have a dedicated cockpit with anchored pedals.

Although I am still adapting to the new feel of this pedal, I am confident my personal best laps will come down. I say that because with the sensor, using my habitual braking points, I found myself entering the corners way too slow. My stopping distances have shortened and I have had to move my braking points closer to the corners. Needless to say, I am a happy man.

The bad news is, Paddy was not able to get his FlexiForce sensor working.

I think the main unknown at this point is, how long will the sensor last?

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Edited by jklhill, Apr 23 2012 - 09:48 AM.





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