http://www.instructables.com/id/6-AXIS-ROBOTIC-ARM/

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6 AXIS ROBOTIC ARMby sparten11 on August 17, 2012

Table of Contents

6 AXIS ROBOTIC ARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Intro:   6 AXIS ROBOTIC ARM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 1:   Motor and Gear Choice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2

Step 2:   Controllers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Step 3:   DA BRAINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Step 4:   Interface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Step 5:   Lets get this party started. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Step 6:   Bare Bones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Step 7:   Bearings you need to get your bearings... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Step 8:   Round about . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Step 9:   Arm Wrestling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Step 10:   The Basics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 11:   Dem Bones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Step 12:   Ending it All . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Step 13:   The Gun Show! . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Step 14:   Software and Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Step 15:   Stay Tunned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Related Instructables . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

http://www.instructables.com/id/6-AXIS-ROBOTIC-ARM/

Author:sparten11    PhantasmNot much to say. Former recon marine, did time in the Navy as well. build robots for a living, engineer as a trade. Inventor, Black belt TKD. battle bots. robotwars etc. Medal of valor recipient.

Intro:  6 AXIS ROBOTIC ARMWell I finally did it. I finally pulled the trigger and started to build a 5/6 axis robotic arm. This is an ongoing project so please check back from time to time to look at theprogress and offer any ideas you might have who knows I just might include the changes. I have alot done so far. I will try to make this a step by step. If any of you needclarification or just more info on how i did that or where do i find that bit of software or that part etc. just drop me an email. So with that said lets get started. Please forgive any grammatical or spelling errors I am in a rush to finish this project please let me know if you see any.

With any robotic project no mater how complex you must plan, plan, plan, and then finally figure out or layout how you will go about it.. or "PLAN"...

This picture is my last concept before i began. I created this layout with solidworks. that way i could test for any interference from moving parts in order to make sure theywould all fit together just right. I also wanted to test for load bearing and lateral forces, as well as motor torque and loads. This information though not needed right awayis a must for later on.

The mechanical layout is just a small piece of the design you must also consider all the programing that will be part of any robot you build especially a 6 axis robotic armwith inverse kenimetrics. More on that later. Once i had the basic layout I needed to make sure i cold afford the parts necessary to build this monster. I had to source themotors and find a supplier, as well as the gear/ drive train for each axis.

The motors i settled on were found on Ebay for 30.00 each. I bought 10 because i want to build more that one robot arm.

Step 1: Motor and Gear ChoiceThis picture shows two of my motors with a controller. The motors as mention above were bought on ebay for 30.00 each. They are brushed DC motors and run on 60volts peak. up to 8 amps. these are strong stable motors perfect for the job. A few things you need to be aware of when building any electrically powered device driven bymotors. one is the voltage you plan on using this gets into available power sources. you have to be able to power your creation once you build it. I choose 60 volt dcbecause i could easily find a DC power supply for them. I will show you the power supply later on. You also need to consider the shaft size of the motor. This is importantbecause you need to be able to find a suitable and low cost yet capable gear reduction system for the robot.

I chose to use a 10 to one reduction encapsulated in a planetary arrangement. this gives me great space savings as well as an efficient power out with good torquecharacteristics. These pictured were found on the internet and brand new cost me 150.00 apiece. Choose wisely when selecting your gear reduction or drive system. Imade a mistake when i chose these units they should have been 30 to 1 not 10 to 1 as a result I will need to add a bellows system to help counteract the extra weight toavoid wearing out the motors and burning up the power supply. I will show you how I was able to fix this issue with very little effort though, sometimes you have to roll withthe punches to get the job done. My solution was simple yet elegant and effective. I will install the Bellow system once I receive the parts i ordered should be here nextweek or so.

The last item you need to be aware of when picking a drive system is not only the motor and the transmition but the feedback system needs to be addressed. All roboticmobile systems need feedback otherwise they will not know where they are in relation to a known point, this is key to control of each axis. I have a 5000 count quadratureencoder on each axis this give me with the 10 to one gear reduction over 400000 counts per axis revolution, and as you may know the more resolution you have in yourfeedback loop the more accurate the robot is going to be. You can see the encoders mounted here in this pic they are located on the end of each motor with the grey cap.Renco makes these encoders.

http://www.instructables.com/id/6-AXIS-ROBOTIC-ARM/

Step 2: ControllersOnce you have the motors and transmission and feedback your next choice will be how to i power and control these babies?For these motors I chose to use a Roboteq motor Controller "SDC 2150" this controller is just awesome It can control two 50 volt DC Brushed motors at the same time,and handle the encoders, and have digital pin-outs as well. not to mention the ability to store your program on board the control as well. it also comes with very goodconfiguration software with a mild learning curve and some of the best tech support i have had. I cannot recommend them any higher. You can find them here they havemany many different controllers available for low power to high power there website is:http://WWW.ROBOTEQ.COM check them out you wont be sorry. These controllersalso have usb, serial, analog and pulse control abilities built right in. you can configure any port to run and digital, analog, pulse and the have can bus as well fornetworking these together. Go and get the PDF from the website.

The next thing i did was to build a cover for my motor controllers.for this I used my 3D printer pictured here.

This Printer is a godsend it makes my life so much easier. Just make your part in solid-works and send to printer, that's it. you can see in this next picture the threecontroller boards with PVC covers made with the printer. Nice, each controller drives two motors. total 6 motors 6 axis lol for those who anrent good at the math. you canalso see in the first picture showing the wires on the motor controller. There are some near my thumb. These are PWM inputs and one power output for RC or radiocontrol. Just like those remote controlled airplanes and cars you see all the time. This comes with each motor controller. This is perfect for me. I am going to drive each ofthese axis with a PWM signal. I will show you how I build the circuit and soldered the boards so I could connect my computer to the drivers and control the robot.

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Step 3: DA BRAINSThe next Item i had to choose was how to control the beast once completed. I didn't want to use my desktop I have too many games to play on that baby. I find that I getvery cranky if I don't get my Battle Field 3 fix once a day. So I looked around the net for a while thought about this pc or that one, weighed the pro's and con's talked tosome of my friends on the matter and after some deliberation and begging for funds from my wife decided on this beauty . It is called a Pico Pc. very small and forpowerful for it size. a full 1 GHz processor, with 2 gigs ram, and hd video output with 4 usb2 ports 1 serial port just what i needed. one sata input as well as ide input forhard drive. It came with all the cabling needed. Though I had to purchase a separate power supply. pictured here.

For the hard drive I wanted to avoid standard platen drives or mechanical hard drives, in doing so I would avoid the failures associated with harsh environments not tomention the bumps and vibrations that were bound to occur. so i chose this one its a 64 GB solid state drive. Nice. this will run windows xp pro as my operating system,without a hitch. Once I get the OS installed I will pair it down to a minimum to reduce its volume and speed up the program to run my algorithms.

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Step 4: InterfaceNow we have almost everything we need to start getting our hands dirty. One last detail I needed was how do I talk to the robot? How do I make programing this creatureslick and so easy that anyone could program and run it without any training? I searched the web and found a slew of possibilities for example there is the Lynxmotionserial servo control board. this is a good choice no reason not to use this one. trouble is some of the software though just fine and works great, requires some programingknowledge. If this is your bag or you just want to give it a try the get this one you wont be sorry, However I wanted an even easier way to program my arm than that.

So I build my own serial interface board and used a different software to control it. HVlabs hand wrote this code. and has a schematic that you can use to build programand run this little baby. I reworked all of this hardware and build my own version. These pictures show the board layout, the schematics, and the are if you want to etchyour own boards. http://www.hvlabs.com/ this link you will find all you need to build your own board. If you cant or don't want to drop me an email I can build them for you.

http://www.instructables.com/id/6-AXIS-ROBOTIC-ARM/

Step 5: Lets get this party started.Now that I have selected all my parts, and have the design done, I need to start the building process and purchase all my crap for this major undertaking.

First is the interface board. Once I knew what i wanted i started with the board. I needed to make it smaller to fit in my robot control box, so i redesigned the boards fromwhat Olly made from HV Labs Website. Pictured is my board and layout. I used PCB software, it is design software that is free on the internet and once you are done youcan have the boards made for you cheap. This is what i did. It works great. You can see the great job they did with the etching.

You can see the finished board after i soldered all the parts onto the board. It came out great. Now that i have the board and the control software that will drive the robot Ineed to program the microprocessor that drives this new board it is a hex file for the pic 16f84 chip HV labs has this file free for the download I had to buy a chipprogramer for this purpose just Google search for a viable programer for the pic chip sets. they are cheap, you can also build one if you want to.

I was worried that i might have made a mistake in designing this new board. Not to mention the issues if you were to solder something wrong or put a part in incorrectly.

Happily this was not the case and the board work like a charm the first time i hooked it up. I have a video of it as well as others that I will add to this indestructible soon.That way you all can laugh at my ineptitude at building this creation.

Step 6: Bare BonesEnough about software and control boards lets build the arm...

With my arm design done all the sizes and parts were already called out on the get go. So all I needed to do was place an order to the local Water jet shop to cut out mybare bones parts. These consisted of the arm segments. Segment ends and motor mount attachments.

Once I ordered the parts to be water jet cut. I went to work on the first major piece of the robot arm which is the Base. this is a complex piece that needed to be heavyand stable it will carry the full load of the robot and whatever it is carrying. Pictured is the main section or the very bottom of the base.

This first picture has a hole in the center where the motor shaft will insert. I will also cut a key way here for the shaft key to fit. I did this right on the lathe using a keycutter, and the tail stock mount to force the tool through the steel.

I also turned the base down this is hard steel or known as hot rolled. It finished nicely, I then turned a pocket form the middle to create the area where my bearing wouldride. This is one of the most important pieces for the robot. This is were all comes together and the primary pivot is located anything wrong here will cause issues withtravel and may not allow the arm to rotate properly.

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Step 7: Bearings you need to get your bearings...Once the base was done I needed to work on the bearing table. This is Totally my design here, so you may not understand the layout. It is not a standard layout by far,but it works for me with what I had in house.

This piece was cut from 7136 Alum. it is as hard as steel and stronger, very light. I cut this into a hex pattern and added 6 special hardened shoulder bolts to hold thesespecially designed bearings in place. The bearings are standard 1 inch diam ball bearings Sealed with a 1/2 inch diam hole in the middle. We rounded the outsidediameter so that they would work more like a ball bearing and have very little surface contact to ease friction and make the turning oh so easy.

I then cut a large diameter hole in the middle to hold yet another bearing that in turn would fit onto the boss left over in the center of the base. See the pictures. Aftercutting the hole i used the flat sides to help me jig up the part so I could drill and tap the bearing mounts. The shoulder bolts actually fit deeply into the part so theshoulder is recessed behind the bearing to help hold them, and add support to them.

After I finished that I then removed all of the bolts and bearings and turned the whole part to make the outside round instead of a hexagon. This allowed the locking plateto fit tighter and support the bearings better.

Step 8: Round aboutRound and round she goes where she stops nobody knows. My next step was to make the lock down plate. This plate would lock down the hex bearing block from theprevious step onto the base. This piece was cut again from Hot rolled steel. It is very strong, and heavy.

First I needed to turn the raw material down, I then cut a hole in the center, I did this with our Lathe which made it easy. Once the hole was cut and the part cleaned upand faced. I then cut the pocked where the bearings would be located. Once that was done I programed My CNC mill to drill the holes in the plate so I could bolt this partto the base. I also programed the CNC to drill and tap the base so I cold finish this piece.

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Step 9: Arm WrestlingNow that the base is Complete I Need to start on the first motor mount and the first moving powered part of the robot arm that is the base and pivot point.

This part I programed for my mill to create. This is made for 6061 alum and is custom fit to the motor where the planetary gearset will mount . this will lock the motor tothe robot. With the motor inserted in the large hole you see the 4 bolt holes that will lock down the motor.

There are to be 6 holes on each side where the side rails will attach. More on that later. See the last pic here you see the motor mounted. I also chamfered the holes toallow the bolts to sit flush with the side of the mount. see the video.

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Step 10: The BasicsNow that the motor has been attached to the main mount I need to build the support and structure to add to the base. This is a complex part and will need to be strongand stable.

As you can see this is the first half of the base interface. The motor mount attached to the pivot segment with the carrier bearing in the middle this will help to avoid slop inthe arm as it travels around the base. I have created a race around the OD of the base that these bearings will ride on. I also added a forward support and mount for thesoon to be added pneumatic cylinders that will act as the billows.

Also you can see the cutout for the next motor that will be added to this part, and will be the second axis of the arm. This will carry the bulk of the weight and soon will bethe cause of my turning to large quantities of alcohol to relive my stress from the inability to tune this part of the arm, Once I was able to make the motor run freely on thebase it tuned up perfectly.

Step 11: Dem BonesOk Base done, pivot and first two motor mount done. I finally received the arm parts from the water-jet folks. They look great. a but load of machine works still needs to bedone.

As you can see the parts fit together great. After I tapped the holes and machined the ends see videos.

In this video I am hand tapping the motor mount for the end of the arms. You can see that in some of the pictures the rough test assembly of the parts. She is not ready torun yet just want to make sure all is going to fit right.

Looks great. just like I Designed her. To assemble the arm pieces I needed to also Chamfer the holes I had to drill so that the bolts would fit flush. I also had to start onthe end motor mounts.

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Step 12: Ending it AllNow I have to finish the mounting brackets for the motors and the bearing mounts for them as well. Here in this pic you can see the very hard alum 7135 alum hard assteel and light. I am using this again to hold the large diam bearings that will fit around the motor and create a pivot point for the arms.

I cut these square just to save time. then bored a hole in the middle and pocketed the arm segment with 3 tapped mounting holes at one end.

I then hot pressed the bearings into the alum holders.

As you can see in the video I also had to turn down the motor housings just a little bit so the bearings would fit perfectly. I then assembled the arm parts to test fiteverything.

Now that the motor has been turned to the right size. Here is a video of the fit of the bearings and the motor.

This is the motor mounted with bearings. Nice fit. I am very happy with how this turned out.

Here this video shows the arm assembled with the bearing mount.

Step 13: The Gun Show!Now to add the arm components and test fit the whole enchilada except for the end effector. that will be last. I have placed these pictures in order of assembly you cansee the arm come together now. I used 5/16 13 thread bolts for this the have a flush mount to avoid hanging up when passing other parts during movement. The bearingsmounted beautifully. Over all I was very happy with the assembly. Once the arm was assembled for the first time I needed to make sure there was free movement for allthe parts and nothing crashed into each other.

With but a few minor issues all fit amazingly well. This is a testament to computer aided design almost no mismatch all parts fit exactly like the should have. The onlyareas that gave me any trouble were those done manually or there was misread setup sheets.

There are still more axis to add to this robot arm however they are not ready to be attached. I have just ordered the end effector part, like the smaller motors gearreduction and encoders these i will add to this once i received and machine the parts to mount them.

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Step 14: Software and ControlNow that I have the arm 80% done I can work on the control of it. In these videos you can see the first test run of the arm. I removed all the major arm extensions to avoidcrashing the arm during testing of the software and motor controllers setup an tuning procedure.

I moved the assembled robot to my office for testing and tuning.

This video shows the robot motors running via HvLabs software for the first time.

This video shows the robot running in tuning software for first time without the arm segments.

Now that I can drive this baby lets see if my idea of easy programing will work. in this video you can see the robot moving via our motor computer interface board and thesoftware from HVLabs. This is Great!

Step 15: Stay TunnedOk Got a lot done here. I still need to finish the end effector as mentioned before. So please check back from time to time to see the improvements to the robot. I also stillneed to add the bellows to the system as well. I will be running testing and upgrading and refining the system as I go. I hope to eventually sell these robot arms with manydifferent tooling options for the little guy who cant compete with the big corporations by cutting the cost of automating there operations. And by making the programing soeasy that a 10 year old can do it. We make this type of system available to the masses, and put more people to work.

Yes you can create jobs by automating. when we automate it allows us to compete for manufacturing jobs that have been shipped overseas. by cutting costs we canbring it back home. Then teach our workers to maintain the robots and build better ones. No denying the facts the world is automating and we need to be right up front.Cheap robots will bring us back from the brink. At least I hope so.

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