RoboSavvy Forum

My Creation! His name is DR-6

2011-05-23T15:14:07+01:00

Very cool. Vids p

Sorry i don't have vids. But anytime i will post vids. because i'm busy right now....

Statistics: Posted by Rick_swarty — Mon May 23, 2011 3:14 pm

My Creation! His name is DR-6

2011-05-19T15:33:32+01:00

Very cool. Vids please!

Statistics: Posted by billyzelsnack — Thu May 19, 2011 3:33 pm

My Creation! His name is DR-6

2011-05-18T18:14:47+01:00

hi i'm back, after long time, last i can return to join robosavvy again. this is my simple work.
this is robot where i create. thr robot used intel atom, controlled uses modified atmega 8535. intel atom with OS windows XP for detection colour and instruction to controller with serial communication. thanks for the mic2 for any advice
http://imageshack.us/photo/my-images/196/photo382q.jpg

Statistics: Posted by Rick_swarty — Wed May 18, 2011 6:14 pm

My Creation! His name is DR-6

2010-03-09T18:16:02+01:00

Hi Mic2

I am going to use whatever is avaible for me in my lab.
I do microcontrollers for living.

Statistics: Posted by bonmot — Tue Mar 09, 2010 6:16 pm

My Creation! His name is DR-6

2010-03-09T18:07:48+01:00

bonmot wrote:
But to be clear to other people reading this thread, 3s LIPO WILL at least give you 10.8V power when running a robot when current is less than 10C.

This looks OK to me.

By the way what kind of controller board you're planning to use for the HV300 servo?

Statistics: Posted by mic2 — Tue Mar 09, 2010 6:07 pm

My Creation! His name is DR-6

2010-03-09T17:50:10+01:00

Hi MIC2

You are right about the over discharging issue. Yes, all my airplanes, helis and cars has a low voltage monitor to monitor each cell, and stop it going below 3.2V. Basically it has 2 stage of warning: warning and cut off.
Of course I don't do cut off on my airplanes and helicopters for the obvious reasons

But to be clear to other people reading this thread, 3s LIPO WILL at least give you 10.8V power when running a robot when current is less than 10C.

Statistics: Posted by bonmot — Tue Mar 09, 2010 5:50 pm

My Creation! His name is DR-6

2010-03-09T17:41:57+01:00

bonmot wrote:
billyzelsnack wrote:Why do you say.. drop down to somewhere near 8.2v? To take in account the voltage of the battery under load? From my understanding Lipo's should easily hold above 3.2v/cell under load, especially in robotics applications which require much less continuous and surge current compared to typical RC applications.

I agree with Billyzelsnack. I use LIPO's for my helicopters. Current is 10A to 30A for my small size chopper. 3.2v/cell is already heavily heavily loaded.

If talking about 10A for the robot walking, we should be able to easily see >3.5v/cell before using up to 70% capacity of the batteries.

Guys,
8.2v is the power cut-off voltage NOT the load voltage! 3cell li-po is 11.1v when fully charged you will get a bit more. When using li-po battery you’ll have to use a battery monitor board to prevent it over discharging, I would recommend not to setting the threshold too low and damage the battery.

For a safety zone each cell shouldn’t drop more than 1v to be trigger the power cut-off point e.g. 3 cell =3v 11.1-3= 8.1v however you can set the voltage higher to achieve a longer battery life.

Anyway I have corrected my bad English.

Statistics: Posted by mic2 — Tue Mar 09, 2010 5:41 pm

My Creation! His name is DR-6

2010-03-09T16:58:43+01:00

billyzelsnack wrote:
Why do you say.. drop down to somewhere near 8.2v? To take in account the voltage of the battery under load? From my understanding Lipo's should easily hold above 3.2v/cell under load, especially in robotics applications which require much less continuous and surge current compared to typical RC applications.

I agree with Billyzelsnack. I use LIPO's for my helicopters. Current is 10A to 30A for my small size chopper. 3.2v/cell is already heavily heavily loaded.

If talking about 10A for the robot walking, we should be able to easily see >3.5v/cell before using up to 70% capacity of the batteries.

Statistics: Posted by bonmot — Tue Mar 09, 2010 4:58 pm

My Creation! His name is DR-6

2010-03-09T15:13:36+01:00

Why do you say.. drop down to somewhere near 8.2v? To take in account the voltage of the battery under load? From my understanding Lipo's should easily hold above 3.2v/cell under load, especially in robotics applications which require much less continuous and surge current compared to typical RC applications.

Statistics: Posted by billyzelsnack — Tue Mar 09, 2010 3:13 pm

My Creation! His name is DR-6

2010-03-09T18:30:02+01:00

bonmot wrote:
I am thinking about this servo:
Turnigy HV-300 Digital HV-3S Servo 38.40kg/ .130sec / 79g.
What's the reasonable size of the robot I can built based on your rule of thumb.

Hi bonmot,
Good price for a Coreless digital servo with Turnigy Alloy case and Titanium gear, refer to the spec of the servo @ (8.4V) - 26.90 kg.cm and @ (12V) - 38.40 kg.cm. Let say you are using 3S li-po battery, the operate voltage would be above 11V and then drop down to somewhere near 8.2v (When Fully discharged Power cut-off point) i.e. around 34 – 25 kg.cm torque, refer to the size and the torque of the servo you could build a robot around 40-52cm tall, depends how light the top half of the body can be. I would suggest using some small light weight servo for the top half of the body. This will reduce servo backlash problem when it is at high speed motion, as well as allowing you to build a taller robot.

However make sure you have made a lot of test between the controller board and the servo before getting into the design stage. E.g. Accuracy, speed, respond time, stress testing (run it at high speed with full travel to see when the body temperature goes up etc. this should give you some ideas of how the performance of your robot can be.

Hope this help
Mic,

Statistics: Posted by mic2 — Tue Mar 09, 2010 1:48 pm

My Creation! His name is DR-6

2010-03-08T03:14:37+01:00

Hi Mic2
Nice job! I am into robotics now, have been thinking about it for years!
I have the same questions about the robot size.
I am thinking about this servo:
Turnigy HV-300 Digital HV-3S Servo 38.40kg/ .130sec / 79g.
What's the reasonable size of the robot I can built based on your rule of thumb.

Statistics: Posted by bonmot — Mon Mar 08, 2010 3:14 am

My Creation! His name is DR-6

2010-03-07T17:21:55+01:00

billyzelsnack wrote:
I understand how dual servo knees doubles the knee speed, but how does it increase knee torque? Each "half" of the knee would still only be capable of each servo's maximum torque output.

I would think that servos in series double the speed and maintain torque and servos in parallel would maintain the speed and double the torque.

I didn't say that it doubles, but divides a bit.

Statistics: Posted by mog123 — Sun Mar 07, 2010 5:21 pm

My Creation! His name is DR-6

2010-03-07T01:53:45+01:00

I understand how dual servo knees doubles the knee speed, but how does it increase knee torque? Each "half" of the knee would still only be capable of each servo's maximum torque output.

I would think that servos in series double the speed and maintain torque and servos in parallel would maintain the speed and double the torque.

Statistics: Posted by billyzelsnack — Sun Mar 07, 2010 1:53 am

My Creation! His name is DR-6

2010-03-06T23:39:28+01:00

Your creation is really swell. I only want to note that the "2servo" knee isn't just for flexibility. It's main role is to eliminate servo backlash, divide some of the torque, and improve knee-bending speed.

Statistics: Posted by mog123 — Sat Mar 06, 2010 11:39 pm

My Creation! His name is DR-6

2010-02-17T22:37:55+01:00

billyzelsnack wrote:
Very very nice.

Thanks I have used a similar walking style call “SHIN-Walk” from Robot Laboratory CHROINO robot.

http://www.robo-labo.jp/english/robot_intro/chroino.html

Which aim to give more naturally walking motion than traditional robots that walk stiffly with constantly bent knees.

Statistics: Posted by mic2 — Wed Feb 17, 2010 10:37 pm