Building a 6-axis DOF robot arm for Lego World 2017, by Sioux.NET on Track

[Hanso]

I have shared some photos at the Lego Photo pool (https://www.flickr.com/groups/lego/), hoping that I would be picked up by the Brothers Brick (http://www.brothers-brick.com/).  Just wondering, is my robot arm not interesting enough? Not cool? Just another 6DOF robot arm from Lego?

What do I need to change to be blogged on Brothers Brick?

Just wondering ... Hans

[Blakbird]

11 minutes ago, Hanso said:

I have shared some photos at the Lego Photo pool (https://www.flickr.com/groups/lego/), hoping that I would be picked up by the Brothers Brick (http://www.brothers-brick.com/).  Just wondering, is my robot arm not interesting enough? Not cool? Just another 6DOF robot arm from Lego?

What do I need to change to be blogged on Brothers Brick?

I don't think you did anything wrong, but TBB hardly ever blogs Technic creations.

[Hanso]

New photos posted on Flickr (all movements implemented now, the opening/closing of the grabber is on the todo list):

 

All six movements can be viewed on Youtube:

 

As you can see on the photos, I have add a manometer (Lego 64065) as well. Just for fun ;-)

 

Enjoy, Hans

Edited January 21, 2017 by Hanso

[BusterHaus]

Looking good, but the rotation of the 5th axis is very jerky. Is it the tan driving gears? 

[Hanso]

3 hours ago, BusterHaus said:

Looking good, but the rotation of the 5th axis is very jerky. Is it the tan driving gears? 

Hi Busterhaus,

I needed to remove the black gears because they were to tight. The two tan driving gears leave a little bit more space, but now the 5th rotation is indeed jerky. I need to look into that. Putting back the black gears is however also not a good option.

What you can't see (I think) on the video, is that movement 4 (wrist roll) often fails. I use the technique you mentioned to determine the end stops. That is, if the rotation power is zero, then it has reached an end stop. But too often the rotation is a bit too heavy, which also result in an (early) motor stop. I will have to look into that as well.

Summarized: it all works, the base is there. But is does not work good enough. But that is the fun part: making it work perfectly.

Thanks again and keep you all posted.

Enjoy, Hans

[Hanso]

Click on the picture to watch a small video with the pneumatic pump and that we reached almost 3 bar with this simple pump system.

Enjoy, Hans

[Hanso]

On 21-1-2017 at 6:44 PM, BusterHaus said:

Looking good, but the rotation of the 5th axis is very jerky. Is it the tan driving gears? 

I have updated the driving of the turntable for the 5th axis, see pictures below. Now this movement is also working fine.

 

Next on the To Do list: adding the pneumatics to control the grabber. Hope to have this finished by the weekend.

Best,
Hans

Edited January 25, 2017 by Hanso

[nerdsforprez]

I have only been a spectator thus far......but must say, this has been a fun project to follow. Lookin forward for more updates

[Hanso]

2 hours ago, nerdsforprez said:

I have only been a spectator thus far......but must say, this has been a fun project to follow. Lookin forward for more updates

Thanks "Nerds for President". Will definitely vote for you when you will be candidate.

Regards, Hans

[Capparezza]

Wow, astonishing. I don't know if this has been done before (I'm not that into Technics stuff), but even if: this thing is just insane!

[Hanso]

14 hours ago, Capparezza said:

Wow, astonishing. I don't know if this has been done before (I'm not that into Technics stuff), but even if: this thing is just insane!

Thanks, Capparezza, for your kind words.

 

The pneumatic has been added to the robot arm. The pneumatic switch is controlled by a Mindstorms M motor.

Photos can be found on Flickr:

 

Video can be found on Youtube:

 

Enjoy, Hans

[Hanso]

And here is a first video of the robot arm picking up a candy container:

It is just a small test to see if the robot arm can pick up a container from a predefined place.

Enjoy,
Hans

[Hanso]

The pneumatic pressure for opening and closing of the grabber, is generated by a motorized pump. To prevent the air pressure to be too high, I made an automatic start/stop system for the motorized pump based on the air pressure. The principle is simple: connect a pneumatic piston to a shock absorber. When the air pressure is high enough, a PF switch turns into the 'stop' modus. If the air pressure is beyond a threshold, the shock absorber turns the PF switch back into 'start' modus.

In the pictures below you see the elements needed for this auto start/stop system:

In total, three shock absorbers (with soft spring) are needed to generate enough backforce for the piston. The result with the air pump and the motor looks as follows:

If you connect this to the robot arm, you see how the automatic start/stop works:

Enjoy,
Hans

Edited February 5, 2017 by Hanso

[Hanso]

Have been busy with 'real work' the last couple of weeks. Finally got some time to work on the project again.

I have written a test program to

I have made a small test program for the robot arm to load the train with two containers. 

Loading the two wagons was done in one minute, so much faster than the candy crane.

Have a look at the video and please share with me what you think of it.

Kind regards,
Hans

[Ramacco]

Amazing build! Will you be sharing the LDD?

[Hanso]

3 hours ago, Ramacco said:

Amazing build! Will you be sharing the LDD?

Thanks for the compliment.

I would love to share the LDD, but I don't have one. And I don't think that I will make one (too much work). You'll have to do it with the pictures, sorry for that.

 

Kind regards,
Hans

 

 

[Hanso]

In one of the previous updates, you can read about the pneumatic compressor with a automatic start/stop. This was a mechanical system: between the battery power and the motor driving the pump, a switch was installed. The switch was connected to lever. The lever was connected to a shock absorber and a piston. The principle worked fine, but it was very difficult to get it fined tuned. The last version turned the motor off at a pressure of 34 - 38 Psi (which was good), but the motor was turned on again when the pressure dropped below 10 Psi. This pressure is too low for the grabber, there was not enough grip causing the container to fell off.

So, I bought a digital air pressure sensor  (Mindsensors, PPS58-Nx):

This sensor reads the actual air pressure with a maximum of 58 Psi. I connected it a Mindstorms NXT:

The minimum air pressure is set to 20 Psi and the maximum is set to 35 Psi. By this means, there is always enough pressure to operate the grabber of the robot arm.

You can see a video of the pneumatic compressor with digital auto start/stop at our Youtube channel:

Enjoy, Hans

[Aventador2004]

That air regulator is awsome!! The robot looks perfectly crafted.

[suffocation]

Why oh why have I only just noticed this topic? That arm is truly impressive. both in looks and in functions. Looking forward to seeing more!

[Hanso]

7 hours ago, Aventador2004 said:

That air regulator is awsome!! The robot looks perfectly crafted.

Thanks, Aventador2004.

 

7 hours ago, suffocation said:

Why oh why have I only just noticed this topic? That arm is truly impressive. both in looks and in functions. Looking forward to seeing more!

And a thanks to your kind reply as well.

 

Happy Easter,
Hans

[Aris]

Nice work. I am fan of pneumatic grippers and industrial style robotic arms. Interesting use of sensors. 

Edited May 9, 2020 by Aris

[Glaysche]

I was inspired by this series of posts and decided to build my own 6 DOF robotic arm.

 

I did things quite a bit differently than this one and had newer parts available to me.  I used the newer Control+ motors and battery boxes.  They are more compact than the Mindstorms parts.  I didn't end up using pneumatics.  I'm sure this is just the beginning of my Lego MOCs.