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51
Mechanics and Construction / [Help] Motor place in mobilerobot
« Last post by Mohamedsaa3d on August 22, 2015, 04:57:55 AM »
Hello , i want to know what is the difference between these 2 options of motor place in the robot plate  :

1 - Motors below the plate
2 - Motors above the plate
52
Electronics / Re: Servo Surge Capacitors
« Last post by cyberjeff on August 20, 2015, 03:27:15 PM »
As a final project in school, my partner and I made a hexapod.  We had 18 servos (3 DOF legs), and a LiPo battery (11.4V I believe)from an RC car.  It was happy when it started laying flat on its belly, then all the legs would push it to standing positions.

I think it depends more on your battery, if it can provide enough current.  If its a lithium battery, it should be OK, because they have high discharge rates.  With a NiMH you may have more troubles.

I think only if your battery is insufficient, would you need caps to help it.

And even if you do use caps, you'd need a delay after your robot is powered on.  It cant stand up immediately, you would need to give the caps time to charge, else you're just increasing the load.


Thanks.

The Li Poly was out of my price range for the Watt Hours I wanted. I hope that changes!

The curious thing about DC permanent magnet motors (I believe that is what my TowerPro servos are) is that when they are drawing the most current they are not producing the most power, and efficiency is going to hell.

http://members.toast.net/joerger/pic2/motorcurve.gif

What this means to me is that the mechanical design of the robot should be such that it never needs to deliver more than half the stall torque. The robot will run faster and need far less amps. More amps is less power! If I stagger the start up sequence, like you suggest, then I won't need more current later.

BTW, most small supercaps have very low load current capacities, so the super cap idea I had won't fly.

When are you guys at Progressive Automations going to have a small linear actuator in the 30kg/cm to 100kg/cm with a short 5cm or so stroke that I can afford? I could put them to work...
53
Misc / Re: We're giving away Free Robots - what would you do with a robotic arm?
« Last post by cyberjeff on August 20, 2015, 02:40:59 PM »
I tossed my hat in the ring with "Lefty, the One Armed, Three Legged Butler Bot", but the video leaves open a multitude of questions, among them:

1) Ballpark weight and size? Ballpark speed and torque?

2) What kind of mechanical and electrical connection exists at the "hand"?

3) I assume if you could 3D print with this it has a high degree of accuracy. Is that so?
54
Electronics / Re: Servo Surge Capacitors
« Last post by ProgressiveAutomations on August 20, 2015, 11:04:09 AM »
As a final project in school, my partner and I made a hexapod.  We had 18 servos (3 DOF legs), and a LiPo battery (11.4V I believe)from an RC car.  It was happy when it started laying flat on its belly, then all the legs would push it to standing positions.

I think it depends more on your battery, if it can provide enough current.  If its a lithium battery, it should be OK, because they have high discharge rates.  With a NiMH you may have more troubles.

I think only if your battery is insufficient, would you need caps to help it.

And even if you do use caps, you'd need a delay after your robot is powered on.  It cant stand up immediately, you would need to give the caps time to charge, else you're just increasing the load.
55
Misc / We're giving away Free Robots - what would you do with a robotic arm?
« Last post by jennyjenjen on August 19, 2015, 08:28:22 PM »
Hi Society of Robots,

My name is Jen and I work at Carbon Robotics. We're a team currently in the Qualcomm Robotics Accelerator powered by Techstars, and we are launching our Kick Ass Trainable Intelligent Arm (KATIA) by opening it up to some of the most amazing hackers, builders, makers, and creatives we can find.

We're giving away 10 robots to the people we find who can come up with the coolest ideas for using KATIA. We have already received some really amazing submissions and we would love to hear yours!

Here's the signup: http://bit.ly/freerobotsSoR

If you have any questions, I'm happy to help out or forward it to our engineers. We're really excited to see what you can come up with!
56
Software / Re: Microsoft Robotics Developer Studio 4 / On Windows 8 / WTF MANG
« Last post by GrimBot on August 19, 2015, 03:18:21 PM »
Additional Thoughts:

I'm thinking the simulation environment is flimsy? Perhaps using the "Compile as Service" option would add more sturdiness to playing with the little robot guy..  but after compiling it I have no idea on how to run the service. I think it tried to open Visual Studio (which I don't have a license for, still on the 30 day trial).

Speaking of that.. is there an alternative to visual studio that will work with MRDS?

What I'm REALLY looking for is software where I can drag and drop some parts onto a moldable frame and assign all those parts to a control panel so I can operate it with button clicks.. but I doubt creating new robots and environments (what if I want dirt to dig in? or bricks to lift? Or to pour water? Weight sensors, etc. into this simulation?... Thats what I really want.. but this looks like the best I can get so far.

Anyway.. would the visual studio version matter? Would it being a trial matter?

Thanks for noodling my rambles.
57
Software / Microsoft Robotics Developer Studio 4 / On Windows 8 / WTF MANG
« Last post by GrimBot on August 19, 2015, 03:02:35 PM »
Hello, I've been trying to mess with MRDS on Win. 8 and am having minimal luck. I am new to this so keep that in mind.

I've followed this tutorial and ran into the problem mentioned in the video.  I have recreated the example as an attachment. Not sure how to fix it.


https://www.youtube.com/watch?v=U5mzODNQSQc


Problem:
 "Duplicate name specified for entity or one of its children. Not adding to simulation:ReferencePlatform2011 "

Other tips:
I think that if you copy and past stuff they are not new instances and those instances are all connected. I don't think that is a problem with this example though.  If you can fix it, upload the fixed sample please.

Also, there is that "RUN" log that starts when you run the simulation. I think it would be good to share these logs for trouble shooting but I am not sure how to export that log. Is there an error log generated somewhere?



58
Software / Re: TLC5940NT Mal-operation???
« Last post by cyberjeff on August 19, 2015, 08:04:18 AM »
I haven't used this yet, although I have one similar on order.

I can think of a couple possible problems.

1) The PWM outputs are sinks, you will need a pull up resistor (~4.7K to TLC5940NT +), if your servo does not have one.

2)One wire devices can have reflections on the line and fail to communicate, particularly if you have other i2c devices on the line.

Don't forget to tie all grounds together.
59
Software / TLC5940NT Mal-operation???
« Last post by ecaits on August 19, 2015, 01:42:47 AM »
As I have to control servos by TLC5940NT in Arduino Uno.
During testing, the servos are not rotated as per command and sometimes it stopped and not working.
The wiring diagram is attached in file.
Simple program I have used for servos testing, given below,

#include "Tlc5940.h"
#include "tlc_servos.h"

#define SERVO_CHANNEL   0
#define DELAY_TIME      20

void setup()
{
  tlc_initServos();  // Note: this will drop the PWM freqency down to 50Hz.
}

void loop()
{
  for (int angle = 0; angle < 180; angle++) {
    tlc_setServo(SERVO_CHANNEL, angle);
    Tlc.update();
    delay(DELAY_TIME);
  }
  for (int angle = 180; angle >= 0; angle--) {
    tlc_setServo(SERVO_CHANNEL, angle);
    Tlc.update();
    delay(DELAY_TIME);
  }
}

Thank you,

Regards,
Nirav
60
Electronics / Re: Servo Surge Capacitors
« Last post by cyberjeff on August 18, 2015, 07:43:57 PM »
Sounds like you're making a Quadroped, or something else that stands up on power up.

Staggering the power-up would be the easiest way of doing it.


Yes, that is exactly what I am making. A cat like quadruped.

My thinking is to to hold it by it's spine on power up so that it goes to either a "sit" or "down". Actually my thinking is a bit warped at the moment as I've been studying quaternians.
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