Shoulder/Arm Rotation Setup

[Oliver Richter]

Hi everybody,

my Inmoov is nearly complete now, the head works well so far.

Now I want to setup the shoulders/arms and I now know, why I had so much respect of them because of the 3dimensional movement and the  (for me) unclear potentiometer situation, the cables thru the holes and so on. On my first trial I cuted one cable. On my second trial, the arm rotates and rotates and didn't stop.

I now have only the rotation of the arm connected and play around with the MRL. Without the potentiometer inside the joint, I can rotate the arm via MRL left or right in very small steps. When I put the potentiometer into the joint and start a rotation via MRL the arm rotates untill the potentiometer jumps out of the joint.

Is there a step-by-step manual/video to setup the complete shoulder/arm rotation. I fear without it my arms are just for decoration...

Btw. I don't really understand the manual when it comes to the potentiometer. I have the square ones.

Should I change the cables only for the left shoulder? In the moment I play around with the right shoulder...

Thanks in advance.

Oliver

[Oliver Richter]

There also seems to be no position of the servo in the joint in which I can move the slider (rightArm.rotation) to left and to right and the arm rotates left and right. There are only positions in which it doesn't matter - the arm rotates either the whole time to the right or the whole time to the left, independendly if I click on the right side of the slider or on the left.

I also read the manual (http://inmoov.fr/shoulder-and-torso/) more than 10 times and it seems, that the potentiometer in the right shoulder should be the normal way without changing cables.

Please help me.

Thanks

Oliver

[Oliver Richter]

Hm...rotation of the left arm seems to work. Has anyone an idea, what I could did wrong for this weird movement?

Thanks in advance
Oliver

[Oliver Richter]

Same Problem in the rotation of the (left) shoulder...there seems to be no way to move the arm forward. Wenn ich tip the slider in the MRL on one side or the other, the arm moves backward until I pull the cable.

The red and the black cables of the potentiometer are changed.

I don't know how to go the first steps to fix the problem. Has anyone a hint for me where to start?

Thanks

Oliver

[Roger]

Hi Oliver, 

Not sure if I could help, I will try as I'm still a newbie and learning everyday..., 

For the shoulder rotation I did a left one as well to start off, not sure why, 

But I think to get it to rotate the right way, the base thing to check is if you can control your motor to turn different angles 

with the potentiometer you extracted, if you can get it to turn left and right and stop, ( which is the zero degree I believe from Gael's tutorial..) 

then I think you are on the right track, and then you mount the potentiometer and test it again with MRL, 

Hope it helps, good luck 

Kind Regards, 

Roger

[Oliver Richter]

Hi Roger,

thanks a lot - I really appreciate your help!

When I power up the shoulder without using the nervo board, I am able to rotate the shoulder via the potentiometer left an right - whatever I like.

When I connect the shoulder to the nervoboard and mount the potentiometer into the shoulder joint, the shoulder rotates all the way round only in on direction until it would break the potentiometer. No matter on which side of the slider I touch.

The situation is very frustrating because I am not able to understand, what goes wrong.

Because you can mount the potentiometer on two different ways - which way is the right one?

Has anyone pictures of the mounted (square-) potentiometer?

Is it correct to change the green and the red cable of the potentiometer of the left shoulder?

There is a sentence in the manual at this site, that I also don't understand:http://inmoov.fr/shoulder-and-torso/

"Now we can mount and solder the cable to the potentiometer. Note the slight rotated position of my potentiometer, your should be approximatively the same. Later you might need to re-adjust its position."

--- SNIP ---

Some hours later...while testing around with the shoulder, the MRL software crashed 2 times ("Brain corrupted"). I had to install new and now I'm at the point thinking about using EZ Robot instead of MRL, hoping this will be more stable.

Waiting of the old Lenovo 8 Tablet makes me sick...I hope, I can use other hardware with EZ Robot...have to read in the community...

Regards
Oliver

[Roger]

Hi Oliver, 

That's ok, Gael Creator and InMoov builders here are very helpful and I learnt a lot so I'm just trying to help out if I can, 

I'm still struggling as well, 

I have attached a picture of the square potientiometer that I used as well for the should rotate, hope it helps. 

Kind Regards, 

Roger

On Saturday, October 13, 2018 at 7:20:02 PM UTC+11, Oliver Richter wrote:

[gael langevin]

Hello Oliver,

Sorry for not helping before, but I had too much work on the bench.

It seems your polarity on the potentiometer is inverted.

Some users encountered the same issue although using Hitec 805BB.

De-solder the Vcc(+) and the Gnd(-) on the potentiometer and revert them.

So you would put the green at the red location, and the red at the green location.

History: when I start creating InMoov, I knew nothing about servo motors, and when it came to designing the shoulders, I went through so many tests to understand why this would need to be inverted and if the wormgear would be reversed printed and so on.

A week nightmare, ahaha! Destroyed a few potentiometers...

Nota: it is a hardware issue, not a software issue, even if you would get EZ, you would need to solve that first.

Let me know how it goes

Gael Langevin

Creator of InMoov

InMoov Robot

@inmoov

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[wilco van toorn]

Also a tip, use a normal pc untill you have finished and know how to use everything.

It is difficult and not easy. In fact inmoov is one of the most difficult projects out there. Why? Because it is years ahead of its time. We are using hardware and software that isnt even finished yet. But as soon as you understand the basics it all makes sense.

Regarding the servos, watch youtube and learn how a servo works. That is important if its new to you.
And there will be videos, wanted to make them at the faire but we didnt get to that due to so many people asking great questions. And i will make them but first i have to go to hospital and fix a small problem. But you can change to ez robot. But the install problems are still there and keep in mind ez robot does not have the brain mrl has. And you can always ask questions at mrl site. Make blog post and get many help. But i know from my own experience it is 98% human error and mostly simpel overlooked mistakes. Like not putting mrl in the right location (C:\mrl is the folder it HAS to be put in).

Ibmoov isnt finished product. MyRobotLab isnt a finished product. Why? Because it is created by people in their precious spare time. Ez robot has a pretty gui. But made by people getting paid to make it. It works great if you want basic control. Mrl has its own great features like yolo, programAB, opencv, and very much more but requires more effort from the user to learn. It took me 4 years and still i am learning but if i am lost i ask grog, kevin, mavo or anthony or gael and i get help. Thats the power behind inmoov and mrl.

If you make a small video of what it does we can understand the problem and often it is a small thing you overlooked.
I am going to make some videos but not before half november. So show us whay you did and what it does and we can help you. Also use a pc untill finished. Makes it way easier for the memory and speed of the program. And if needed we can do remote help.

Gr. Wilco

[Oliver Richter]

Wow, thanks to all helpers!

I will watch Youtube videos about servos to understand them better and I think about buying a Windows notebook (normally I only use Apple stuff).

To explain my problem better and for showing the actual status of the project I made a short video and loaded it up to Youtube - perhaps you have the time to watch and give me the next hints for mastering the shoulder :)

For solving the problem I disasembled the almost ready shoulder.

https://www.youtube.com/watch?v=gbIbdIVobLg

[wilco van toorn]

The servo won't work if the pot isn't put into the shoulder. The pot rotates with the shoulder part until it reaches its position. You must put the pot in the shoulder in such a way that the shoulder is in its rest position. If you then hook up the nervoboard and use a slider, then the servo moves to the position its ordered. With the pot in the potholder not put in the shoulder mount (where you put the pot in is the potholder. ) it will never work the right way.
Put the potholder (with the pot in place like you have) into its part and then try again.

[gael langevin]

Hello,

Thanks for the video.

All works exactly like it should in your video.

The fact that the motor starts to rotate without stoping when moving the slider in MRL is normal, because the motor tries to move to the desired cursor position, but cannot find it because the pot doesn't move along.

Now if you set back the pot in the shoulder it should find it's desired position.

As Wilco says, there is a small notion about servo function that you need to understand, and it will all make sense at once!

The potentiometer, that is normally inside the servo motor, is not a ON/OFF button but more acting like a position meter. From 0 to 180 degree.

When the motor turns, the potentiometer turns along and measures the position of the motor from 0 to 180.

So, let say, you move the curser in MRL from  0 to 30, the motor will spin until the potentiometer reach 30 degrees and stops the motor.

But if you remove the potentiometer from inside the servo, the motor will spin on and on because the pot doesn't move along.

Hope this helps to understand better.

Gael Langevin

Creator of InMoov

InMoov Robot

@inmoov

Le dim. 14 oct. 2018 à 16:56, wilco van toorn <wvan...@gmail.com> a écrit :

The servo won't work if the pot isn't put into the shoulder. The pot rotates with the shoulder part until it reaches its position. You must put the pot in the shoulder in such a way that the shoulder is in its rest position. If you then hook up the nervoboard and use a slider, then the servo moves to the position its ordered. With the pot in the potholder not put in the shoulder mount (where you put the pot in is the potholder. ) it will never work the right way.
Put the potholder (with the pot in place like you have) into its part and then try again.

[Oliver Richter]

Hi Wilco,

thanks for your help - I very  appreciate it!

I've put the servo into the joint and startet the MRL. The shoulder moved some degrees after starting the left arm and then stopped.

After setting the setting for the shoulder rotation in MRL from 30 to 31 degrees, the shoulder turns around like 60 degrees or something like that. Putting it back to 30 degrees, the shoulder turns all the way round in the same direction and the potentiometer make a round hole out of the former slot in the joint. That is what happens and I don't understand, what is my mistake...

Same thing happens with the rotation of the right arm. The rotation of the left arm works as expected.

I extended the former video - with the link you start with mounted potentiometer: https://youtu.be/lI-AVUgAyto?t=294

[wilco van toorn]

I think you reversed the pot. But first of all you will need to reprint your gear, that will not work. 

Gael wrote it perfectly, i could not write it any better. But i will make a video tomorrow to show how i do it and how i adjust everything. Also how did your gear get round? before that it should have destroyed the potmeter.

But i have to note that the plastic square pots are very very sensitive, and i will order some from aliexpress, the round ones. Those are a bit better, although those are knockoffs of the expensive ones. But they work so its fine enough.

Ill upload a video tomorrow on how i put the pots in and adjust the 0 position.

Gr. Wilco

Op zondag 14 oktober 2018 20:30:44 UTC+2 schreef Oliver Richter:

[Oliver Richter]

I OK, I think I got it!

Mounted an other potentiometer and it works as expected. Juppiduuuuh!

So I wanna switch over to the more rubust potentiometer - could anyone give me a hint, which ones I should buy?

[Oliver Richter]

And please - no AliExpress-Link because I don't support them and I want to have the parts before Christmas 2020.

In the moment I cannot find any potentiometer with 20mm diameter 5k or 10k with the connectors on the right side to mount them into the original holder. Perhaps someone can help me. Thanks a lot!

[Oliver Richter]

If someone of you have some of the needed potentiometer, please tell me. I would like to buy it.

What I don't want: Fumble around with the printed parts, using hot glue to fix parts or something like this. At the end I would like to have a good looking Inmoov.

[wilco van toorn]

Yes it works! Video or it didnt happen! Haha.
But that gear with round hole is something you will need to adress! Just to be safe.
I just tested the new shoulder and need to reprint a wormgear. Wasnt good. But i will make the videos this week. You could use 5k pots mono with the round tip and make it fit the holes. But ali is one of the few that have the ones we need as servo pot change. Have to order those from ali too. It happens.

[Oliver Richter]

Hahaha...you're right...only posting videos of the problems and not of the success :D

I swear...if I got the potentiometers and have the shoulders moving, I will make the next video!

The round hole in the gear needs to be fixed - you're right.

But for now it seems to be the difficulty to get some of these potentiometers.

I tried to buy them at AliExpress but in the basket they disappear - I hate this shop.

Starting on the german site and ending with spanish questions...they don't know, what they do.

I've build too many online shops for this shit (sorry).

If anyone could give me a hint, whereelse I can buy these kind of potentiometers, I would appreciate it.

Thanks in advance and thanks for your patience with me.

Oliver