Recent Posts

Pages: 1 ... 7 8 9 10
81
Electronics / Re: DC Motor only runs .5 seonds and stops, then starts again
« Last post by Schlayer on March 17, 2015, 07:41:57 AM »
   There are probably a lot of geared motors with large amounts of torque at the expense of speed that can run at lower than 12V. I found one motor with a massive gearbox mounted to it that takes just 5V DC. In hopes of using it for a display stand turntable, I was able to solder a switch to it and then splice on a regular old AC/DC converter wall socket from an unused cell phone charger directly to the switch and motor contact. It works like a charm and has so much torque I cannot physically stop it from turning with my bare hands, which is pretty good for something that takes less than half an amp of current! It only turns at like 10 RPM, but for my purposes that was fine. What kind of speed requirements do you have for your project?
82
Mechanics and Construction / Re: Suggestions for Motorizing mannequin arm
« Last post by RainMan on March 16, 2015, 09:00:16 PM »
Thanks for the reply . I have linear actuators at home and thought about it , but just not seeing the mechanics that well . I would have to get a piece machined for the actautor to push on by a pivot point . So I think I'll look at other options .
Thought about the wiper motor but again no feed back

I'm really liking that motor in my last post , although I wish it was geared lower like 10 rpm but I think it will run down to 3 by adjusting the voltage .
Just have to study encoders now
83
Mechanics and Construction / Re: Suggestions for Motorizing mannequin arm
« Last post by bdeuell on March 16, 2015, 08:46:28 PM »
many types of motors can maintain a position but the system must be designed accordingly. RC style servos are typically brushed dc motors with a gear reduction, potentiometer position feedback, and a built in feedback control circuit. the feedback loop in a servo enables the motor to actively maintain a position. there are methods of electronic braking but that may not provide sufficient holding force in your case. additionally you can get motors with a break that is controlled like a solenoid.

if you go the feedback control method you may want to read up on PID. you could use an encoder, there are absolute and relative styles. an absolute encoder can identify the current position not just change in position. the best feedback sensor for your case might be a simple potentiometer (easier to read also).

all that said I recommend looking at linear actuators. i think the mechanics will be easier because you wont have to deal with a high torque joint. also depending on the mechanics (if it is a leadscrew) it may be inherently not backdrivable. And of course it would look more like the actuating cylinders seen in the terminator movies.

A worm gear motor would also be a decent choice as they are typically not backdrivable. a good source for these is car window and wiper motors (i have picked up a few for free before, robotics stores/sites also sell them). they pack a lot of power but are relatively heavy.

84
Electronics / Re: Motor selection
« Last post by bdeuell on March 16, 2015, 08:22:41 PM »
I am aware of some brands that produce high quality motors such as Maxon and Portescap but i'm not sure if they get into the bigger sizes you are looking for. I would focus on finding a motor that best fits your requirements then if you still have several options look at how well they are built or the manufacturer but i think that first part will narrow your options much quicker.
85
Mechanics and Construction / Re: Suggestions for Motorizing mannequin arm
« Last post by RainMan on March 16, 2015, 08:05:07 PM »
Another option . Although I don't know anything about encoders ? Hopefully I can figure it out and it works with a stamp . Not sure if the motor was moved if it could be put in the same location though as it sounds like encoders tell it how far to move but doesnt know where it is exactly

http://www.superdroidrobots.com/shop/item.aspx/ig42-24vdc-right-angle-024-rpm-gear-motor-with-encoder/1829/
86
Mechanics and Construction / Re: Suggestions for Motorizing mannequin arm
« Last post by RainMan on March 16, 2015, 07:11:38 PM »
https://www.servocity.com/html/vertical_shaft_worm_drive_gear.html#.VQd98RhOKrU

If this had feedback it would rock

Here's the beginning of my build . The mannequin has to be modded a lot . I just threw together quick till I get all my parts

87
Software / Which programming language or platform to start with?
« Last post by lexxtoronto on March 16, 2015, 06:31:17 PM »
I really want to start looking into robotics programming. Ive done some research and there are many different languages used for robotics programming. C/C++ are not my favourite languages, but if I have to I will work with them.

I would like to start with a language that can also be used to other purposes because while Im perfecting my skills in that language or looking for a job in robotics with that language I would be able to work somewhere else since robotics is a narrow industry and I dont want to spend time learning a language that I can't use anywhere else in case it takes years to land a job there.

(1) I was thinking of Python, I think I read it here somewhere that Python can also be used for robotics programming, and of course it is used for web development.

(2) Also Microsoft has Robotics Developer Studio that uses C#. It is also a good option (because of ASP.NET), but I don't know how serious this Developer Studio is, I mean will it help me land a job or is it just for learning purposes?
88
Misc / Re: Presenting a Robotics Project
« Last post by Schlayer on March 16, 2015, 04:33:41 PM »
@Ibaeni > My project is also a senior project, though unfortunately my school is just a typical high school, so nobody reviewing the project will know what I'm talking about.Your suggestions do sound helpful, and I was planning to break it up somewhat. I'm not totally sure what exactly I'm going to program it to do yet so software will need to wait for a bit, but I can definitely separate those aspects of it. Thanks!

@bdeuell > A flow chart is an excellent idea! I hadn't really thought of that, I can definitely try and work something like that out. I'll probably make people interact with the robot's sensors to make it do stuff, I'm not super comfortable with handing the radio controller over to a reviewer however. My brother built a state competition winning robot operated with the transmitter I used for my prototype car, and even he managed to crash it into our garage XD. The final version being as powerful as it should be, I'm not so sure about relinquishing all control, but I can probably make an interactive robot program :) That's a great suggestion, thank you!

@mklrobo > Like probably every high school-er in America, I'm rather familiar with PowerPoint and the whole Office suite :P. Because of that, I was hoping to do something a bit more original like what bdeuell suggested, but I may use a PPT as my background graphics/video section of the presentation. Thanks to you too!

I'm still open to other suggestions, if anyone else has more awesome ideas! :D
89
Misc / Re: Presenting a Robotics Project
« Last post by mklrobo on March 16, 2015, 03:50:04 PM »
 :) Hello!
I would recommend using Microsoft's PowerPoint, in their office package.
The software is straightforward, and the learning curve is not fatal.
Many corporate presentations have been done on this, so it may be to your
advantage to use it. You might be able to have a screen on the robot to
present a powerpoint presentation, explaining the robot itself.(?)
Good Luck!   ;D ;D ;D
90
Software / Re: Programming motor to run for 10 sec?
« Last post by mklrobo on March 16, 2015, 03:42:37 PM »
 ;D Hello!
I agree with Billy, that it would easier and more efficent to
buy a timer that takes an input from a sensor.
Otherwise, if you build your own, it may be described like this;
The sensor feeds into an Op Amp that acts like a comparator,
looking for the voltage level to change when the sensor is
activated. the logic level comparator activates a transistor,
which, in turn, activates a 555 timer, acting like a one-shot
flip-flop.(timer) The timer activates a control transistor that
grounds the control side of the relay; the Normally open
contacts of the relay are used to power your motor, for the
time generated by the 555 timer.
I would probably use a pre-made timer with your sensor.
Good luck!!  ;D ;D ;D
Pages: 1 ... 7 8 9 10

Get Your Ad Here