Society of Robots - Robot Forum

Electronics => Electronics => Topic started by: jamieyello on May 06, 2016, 07:35:34 PM

Title: New to robotics, my project
Post by: jamieyello on May 06, 2016, 07:35:34 PM
Hi, I'm looking to get into my first robotics project, I'm fluent in BASIC and less so in c++, I want to be able to control a robotic arm that will mimic my own with as little latency as possible, along with a couple other functions.

I want to run a portion of the software on windows, where the position of my arm among other data will be determined (I will have kinect sensors along with other motion tracking peripherals), that will be sent over to a raspberry pi, which will serve as the motherboard for the robot. Two cameras will be set up to the pi, the pi will send the footage over a video transmitter like this one
(It looks like it wasn't designed to work without a line of sight, but it also seems to have very little latency)

The footage I will combine into video that can be sent to an HMD such as Oculus Rift. The Oculus will supply camera position as well (to be sent to the Pi).

The robot arms, I will not be going the traditional route with. Normally when someone would think to build a robotic arm they would go, "Ok, servo motor at the elbow and other servos wherever the arm needs to be turned." However I feel like that's not as efficient as it could be, what I want to do is replicate the way a human arm works, and hopefully replicate that same naturally designed efficiency, doing this by copying the leverage obtained by muscles and tendons using wires. I also want it to be fluid like a human arm would be, when I see robot arms they're always jerking around, usually barely keeping up. I feel like work could be done on the software end to take into account the inertia and smooth things out. I also feel like that's the work of servo motors.

So you get where I'm going? Tl;Dr, robot avatar with single arm. Future additions will include legs a body head and if I'm feeling ambitious maybe another arm.

So bottom line, the software, I'm fine with. Hardware? I'm still ok. I've never done any soldering, no engineering of any kind. DC motors vs Servo motors, do servos require more power? Are they less efficient? Less torque? I can't find any solid answers to any of these questions. What kind of materials and tools will I need to create the arm? A saw of some kind? It might seem like I'm not knowledgable enough to take on an ambitious project, but then I am self taught in most things I know. If nothing else I hope I amused you with my ramblings.

One more question, what is the strongest motor available to the public around the size of a bottle, does anyone know? I've wanted to know that since I saw Jamie from mythbusters use the supposed motor to make a grappling gun.
Title: Re: New to robotics, my project
Post by: bdeuell on May 07, 2016, 10:26:05 PM
Selecting the best motor for an application depends on many variables. If you are looking for precision dynamic control with the best weight to power ratio servo motors are probably the best choice.

Note: s servo motor is technically any motor with a feedback control loop. RC servos to fit this definition but are likely below the performance requirements you are looking for. in industrial applications a servo typically refers to a brushless motor with encoder feedback... this is more along the lines of what you need.

Maxon offers some very powerful motors for their size.

Also your mechanical construction will be key to smooth operation, any backlash will result in jerky motion.

Title: Re: New to robotics, my project
Post by: jamieyello on May 09, 2016, 06:53:54 PM
Hi, thanks for your reply. I've decided since this is a big complicated project first things first I just want to get a feel for creating things and just working with metal.

I have started looking at Maxon motors, I think I will be getting one of those, I'm looking at the ones in the $100 range to just mess with for now.