Author Topic: 4-leg 16-servo robot: choosing a controller  (Read 1816 times)

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Offline anvoiceTopic starter

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4-leg 16-servo robot: choosing a controller
« on: June 28, 2015, 02:30:38 PM »
Hello,

I am very new to robotics (science degree), but would like to learn as much as I can. As one of my starter projects, I am making a 4-legged, 16-servo (4 servos/leg) walking robot. I was hoping it would be a platform for me to learn both robotics, electronics and programming, so I would give it more advanced capabilities as I go along. Planning to start by making it walk and do other basic commands, send sensor data, etc. The arduino should be sufficient for this purpose. I'd like to eventually move on to streaming video to a PC/phone for remote control, then semi-autonomous operation where the robot can start making some of its own decisions to avoid obstacles, climb stairs, etc.

One of the problems I am facing is the best choice of microcontroller/computer for the robot. I did read a lot of material on the topic, but couldn't find a definitive answer as to what would be better for my specific project. Specifically, I am choosing between an arduino and a raspberry pi, and would like to hear opinions on which might work.

The arduino has the advantage of being easy to program and use, easy to interface with sensors, and has the "real-time" capability to control components directly. I already know how to use the IDE and have interfaced with most of the sensors I'd like to use, so definitely a plus. However, it has a limited amount of processing power and RAM, so by the time I get to making the robot autonomous, it'll have to send data to a server and receive instructions back. It'll also struggle with sending video too as far as I know, unless I get a separate wifi webcam which has numerous issues. If the arduino works for those tasks though, by the time I've gotten to the point where I'm ready to put in a more advanced computer (learned Python, etc.) I'll have gotten a bunch of practice in with controlling the robot. I see the main problem being whether the arduino can handle shuttling video/command data between the robot and server at reasonable speeds, but I could be missing some other important considerations.

I'd appreciate hearing any ideas or thoughts on this topic. Thanks for reading.

Offline mklrobo

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Re: 4-leg 16-servo robot: choosing a controller
« Reply #1 on: June 29, 2015, 03:15:34 PM »
 ;D Hello!
Based on where you are, and where you seem to be going, I would recommend shooting for
the best of both worlds. Cost a little more, but the trajectory will sustain your endeavors.
You seem to be in constant improvement mode, advancing your techniques, which, in turn,
demand more techno-equipment. This is the same dilemma I have found myself in, and so,
I bought a Raspberry Pi 2 and an Axon II. (I also have a Parallax propeller) The Pi is the brains of
the outfit, while the Axon will handle the immediate concerns. Both have potential in starting out,
as well as using them as tools to learn ARM architecture, to advance to other projects. Since I
am not as rich as Bruce Wayne, (Batman), I will have to reuse what I have to combat my
ignorance. An advantage you might consider is a forum(this one  ;D ) in which someone else is working
on a similar goal, which may eliminate time wasted, and continue at a comfortable pace which
allows you to enjoy the building of your projects.   ;) :) :D ;D

Offline anvoiceTopic starter

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Re: 4-leg 16-servo robot: choosing a controller
« Reply #2 on: June 29, 2015, 05:36:10 PM »
Hi, and thanks for the response.
I do hope that I'm in constant improvement mode, the downside being that I'm not yet knowledgeable enough to even know which resources are available. For instance, I learned of ROS (robot operating system) after I made this post, and clearly that's not running on an arduino. On the other hand, starting with the arduino board will let me start learning more right now, while I still don't have the programming/technical skills to utilize a more advanced system.

My guess at this point is that I'll start with the arduino board despite possible limitations, and push it as far as it will go. Fortunately, I have a 3d printer, so I can make prototypes rather quickly and inexpensively (e.g. I designed, printed and constructed the body of the robot within a couple of days), that's a big plus.

Since eventually I want autonomous operation of the robot, possibly running ROS, wireless transmission of sensor/video data, etc, there is no doubt that I'll be getting a more powerful system, probably starting with a raspberry pi 2, in the near future. I just wanted to hear some expert opinions on whether some of my simpler goals are feasible on the arduino board, since I will have to rebuild the robot partially if I'm to swap out platforms and I'd rather not do it from the start.

Hopefully I'll be able to get a head start with the current setup, and advance from there. I'm always open to suggestions and hearing new advice.

Offline artbyrobot1

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Re: 4-leg 16-servo robot: choosing a controller
« Reply #3 on: July 10, 2015, 02:56:34 PM »
I'm building a full on realistic lifesized humanoid robot like Data on star trek.  I'm planning to use a mini fanless pc or tablet to do all the major coding and have that mounted in the chest of the robot.  Possibly have multiple tablets/mini pcs mounted in the body.  Then, I will interface those into an arduino for lower level processing like determining what the sensors are reading, adjusting servo positioning, etc.  So the flow of the "brains" is regular pc running Linux/windows and running c++ > connects to arduino(s) > connects to servomotor controller boards > connects to servos/sensors.  You can check out my project at twitch.tv/gardogg or on youtube username "artbyrobot."  My username is artbyrobot on my facebook,instagram,twitter,tumblr, etc too if you prefer those.

 


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