hi, im very new to the robotic scene, but i am making a robotic arm from carbon fibre for a college project. the arm will be driven by 3 DC motors, 1 for rotation of the arm and 2 for the moving of the 2 parts that make up the arm. the drive mechanism are small chains and sprockets that are attached to the motors. 2 servo motors will operate a gripper connected to the end of the arm, my problem is i am trying to run this off a ps3 remote i need atleast 10 channels and found this as my only option. i have become lost in info about the controller and looking for any one that can help. what is the simplist way to do this?? is it a matter of wiring all motors to a reciever or will i need a driver chip, if so any models you may know of that will work for me.?
any help is appreciated…
I’m assuming the 3 dc motors have a gear head included. Do you have any method of feedback in the assembly?
ya the 3 dc motors are geared down they are MFA/como drills geared 250 : 1, no i have no feed back i thought that i could run the motors just forward and back with a controller which inturn pull the chains and move the arms components…
No feedback means no accuracy. If you can figure out how to get pots in the joints then you have a chance of making it work. Without it… Well I’m not going to waste your time telling you the ways to try as they are all bad ideas.
Ways to try? Buy an LM ARM KIT!
Alan KM6VV
i dont mind waisting my time if there is a chance it can work… can i not use a closed loop system with speed controlers???
sorry for my ignorance but what is an LM arm kit?? what does it do?
If it would work reliably on any level you wouldn’t be wasting your time. You sure can use a closed loop system. That’s the only way it can work. But the closed loop system you are referring to requires a pot or encoder or some way for the controller to know how far the motor moved the assembly. Alan was referring to one of the robotic arm kits we sell. We being Lynxmotion (LM).
In fact even the no feedback method requires at least a limit switch. You move the assembly until the limit switch closes then the controller knows where the motor is. Then you keep track of how long you turn the motor on to move the arm into the positions you need. Theoretically when these sequences are repeated the arm should repeat the same movements. The problems with this system are anything that changes from the time you trained it. Things like battery or wall pack voltage, ambient temperature, humidity, gravity, sun flairs, phase of the moon, quarks, leptons, and bosons activity, etc. will adversely effect the repeatability. If your using the arm to lift something the movements will change depending on the weight of the object.
ok now i see what u mean,if i changed from DC motors to 3 steppers instead with a genie chip, each motor having its own independent board, would i be able to wire each board back to a reciever for a controller???
That makes no sense.
You can run three open-loop stepper controllers, but steppers normally don’t have enough torque, unless you get special gear-head steppers.
You need DC servo motors with encoders, or use R/C servos as has been mentioned.
Sounds like you’re really not up to speed on motion control systems. For any success, you should initially choose a kit as has been mentioned, or copy a real arm.
Check out the Scorbot,
tech.groups.yahoo.com/group/ScorbotUserGroup/
It uses DC servo motors, and simple encoders. commanded from a PC or pendant.
http://xa.yimg.com/kq/groups/19426739/homepage/name/homepage.jpg?type=sn
But guess what? It has 6 or 7 servos.
Alan KM6VV