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1
I have attached 4 Ultrasonic Sensors on my motor driven autonomous robot. It has a servo-driven steering.
I am using Arduino mega to program the robot. The values of all 4 sensors are pretty accurate when I see them on the serial monitor with the motors off. But as soon as I turn the motors on, I start getting junk and inconsistent distance values on the serial monitor. I did this test while the bot is on the Jack, so it is not moving when I turn the motors on.

I guess this is happening due to the interface to ultrasonic sensors due to vibrations of the motors. Therefore I am guessing these junk values would increase as soon as I keep my bot on the ground.

Please helm me remove these junk values and figure out a way to get exact distance readings while the motors are running.
2
Misc / all Axon prices reduced ~7% starting today
« Last post by Admin on February 22, 2017, 04:43:18 PM »
New year, new prices.

7% reduction on all Axon, Axon II, and Axon Mote prices.


http://www.societyofrobots.com/shop.shtml



3
Mechanics and Construction / Gearbox cleaning
« Last post by ericthet on February 21, 2017, 03:41:53 PM »
I picked up a used liberty differential drive wheelchair and started stripping it down.  I added a Sabertooth 2x32 motor controller and noted that the current pulled on one of the motors was about twice the other one.  This wheel also ran about 10RPM slower and struggled more.  After taking it apart (I thought it might be the electronic brake) it appears it might be the gear box.  I only have the other motor to compare to but the gearbox takes about twice the power to turn and feels "sticky".  I don't hear a lot of grinding or mechanical noise it is just slower/gummier.

I did pull the gearbox apart real quick and noticed it full of gear oil or grease.  This is where I am kind of stuck.  I am not sure if the oil/grease is the problem (went bad?) or if maybe the bearings went bad.  My guess is the bearings as the oil/grease appears a healthy color.  However I don't know what kind of lube is in it or what to replace it with if I rebuild.

From what I can tell it is a 1:19.3 reduction (printed on a sticker) and the manufacture is MTM.  There is a serial code but searching doesn't pull anything up.  I am hoping to rebuild this gearbox as all the mechanics work nicely together.  I have a metal lathe (and know a bit how to use it) and have some basic mechanical knowledge. I am stronger in the electronics side which is why I am starting with this base to get going.

My big questions are:
1. What gear oil/grease should I rebuild this with and is there a way to tell what it is currently?
2. Is there an easy way to tell why the gearbox is struggling? 
3. Is there a way to test the bearings?

To rule out the motor I am thinking of putting the suspect gearbox on the good motor and vice versa and see if the problem persists with the gear box.  I am pretty confident it is, as the current was the same on both motors when the gear boxes were removed.  Also it is very noticeable that the suspect box has lag when hand turning.

For some reference the motors are 200W 24V.  With the gearboxes the good one only averages around 1-2 amps with no load.  The suspect unit was about 4-5amps no load and ran about 10RPM slower.  Without the gearboxes the motors were under 1amp no load. 

If I rebuild the one I might need to just rebuild the other if I need to ship bearings to get them to a known good state....

Any help would be.. helpful!

Thanks,
Eric
4
Misc / Hello
« Last post by M on February 21, 2017, 05:17:26 AM »
Hello. I am a mechanical engineering student. I am very interested in learning robotics. Its a part of my journey to find my passions. Anyways, I don't know where to start. My experience in robotics is that three years ago I made an RC car on aurdino, with wired, wireless controller and also controlled by laptop. I didn't learn the whole language, only the one needed to make the car. The basics. Then, two years ago, I made a line follower and a wall follower two years ago and last year, I learned to make a robotic arm in a seminar by A set. Since all the lessons were in seminars, they were quick and event based. No permanent learning, I hope that makes sense.

 So now I am here. I decided to learn how to make a drone. I read some notes about it and I am not sure what exactly to do in order to start. The first step?? And what is the purpose of learning the kinematics and dynamics of it. Is it helpful in programming? And how to learn programming a quad copter. And is making a quadcopter a good choice? Or should I start with something else?
Edit: Sorry I didn't see the "For the beginners" thread. I still hope that people will help. sorry and thank you.
5
Electronics / A new Friend for you and your kids CooKid-Intelligent Robot
« Last post by carloliu on February 21, 2017, 12:06:43 AM »
Are you dreaming to have a more new friend for you kids which can chat with them , dance with
them, study with them? I think you will want this amazing item for you and your kids.

Cookid intelligent humanoid robot is this unbelivalble product which is invented by SHENZHEN COOKID TECHNOLOGY CO., LTD. which is is a high-tech innovative enterprises specialized in robot R &D, production, sales and service. 
Cookid, as the first generation of Cookid?s independent brand product, has been integrating the multiple functions of entertainment, education, remote control together. In the near future, Cookid will gradually launch consumption grade intelligent service robots, commercial intelligent service robots, smart home robots and other smart products to make intelligent robot accessible to every family and all walks of life, playing different roles as family members, partners that accompany children, assistants in the work.
Firstly I'd like to introduce you our Cookid 1 S which is hot selling in China and the world.
Attached you can find the technical details of Cookid 1S.
For Cookid 1s is with 17 DOFs( Joints) , it can do  dance, singing, story telling controlled by APP , PC , you also can do 3D Programming your actions  via PC
Besides above  functions, , there is big improvement on speech Control, you can voice command Robot to do many actions.
please watch this vedio at

and
( the test video from our customer)`
Further more, there are many new functions, remote security monitoring, smart home management, life reminder, Kids' Education and so on.

This year, we will launch phone size robot Mika and 35 DOFs Robot Cookid 2 with real hand.  I will keep you updated.

We'd like to establish long term cooperation relationship  with your company as we know you are do best work on the high tech sales in your country.

If you are interested in our product or you want more information about the prices or tech details, please don't hesitate to contact me. I will give you our feedback ASAP.

Hope to get your reply sincerely.

Best Regards



Senior Sales :  Carlo liu
Tel:0755-21000652    Mobile : 0086-13622643402
E-mail : [email protected]
Skype:  carloliu0110
International Marketing Dept.
Shenzhen Cookid Technology Co., Ltd   
Adress:  Room 1802-1805 ,18th floor, Jiaanda Building, No.111, Huafan Road, Dalang, Longhua New District , Shenzhen, China   
Web:www.zhsrobot.com
6
Mechanics and Construction / Re: Robot wheel/omni Directional Wheel
« Last post by aika2016 on February 20, 2017, 03:05:59 AM »
Dear friends
 
I am working on a soccer robot for robocup competitions. I have found some interesting omni directional wheels for my robot which has some significant advantages. It is thinner and lighter than the most of the other omni wheels. Moreover it has a good friction and I could move my robot very easily and efficiently.
I want to suggest you to see these interesting omni wheel
the website is :

omni wheel
 does anyone have use them already?
7
Electronics / Trying to read battery voltage from ADS1115 to Raspberry Pi
« Last post by forcel96 on February 19, 2017, 06:56:16 AM »
Hi all. I have a solar powered Raspberry Pi setup and I am attempting to read the battery voltage from the battery to the Raspberry Pi. I am told that I should be able to accomplish this with an ADC. Unfortunately I have very little understanding of electronics and wiring so I am hoping to get a few pointers...

I have looked over this link already:
https://learn.adafruit.com/adafruit-4-channel-adc-breakouts/signal-connections

The main question I have is exactly where in my setup the ADC will fit. At the moment I have the following:
- 3.7V battery connected via 2-pin JST-PH to the USB / DC charger (https://www.adafruit.com/product/390)
- USB / DC solar charger connected via 2-pin JST-PH to PowerBoost 500 (https://www.adafruit.com/products/1903)
- PowerBoost 500 is powering the Pi via USB cable.

So I am unsure of exactly where the ADC should fit into this setup. Would the ADC need to be wired to the battery, the Pi, and the charger? Would the ADC be between the battery and the charger, and then grounded to the Pi? Or is there perhaps an output from either the solar charger or the PowerBoost that I could connect to the ADC to get the battery input?

Any help would be greatly appreciated.
8
Software / hello which software are used in robots??
« Last post by RITESH29 on February 17, 2017, 07:13:19 AM »
hello,
which software are used or to be used in robots please tell.
9
Robot Videos / Motion Planning GUI for Humanoid Robot NINO
« Last post by karthikram570 on February 17, 2017, 06:45:19 AM »
10
Software / Using a rotary encoder
« Last post by vinnygalbo on February 16, 2017, 01:15:27 PM »
Hi,

The only 5 pin rotary encoders I have encountered used 3 for 'encoder' part and the other 2 pins were for a momentary push button in the shaft; I haven't seen one that names a 'CLK' signal etc. I'm trying to see activity in the serial monitor. The encoder in question is an Accu-Coder.

http://www.clrwtr.com/PDF/Accu-Coder/Accu-Coder-960-Absolute-Encoders.pdf

Thank you in advance for any help.
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