RE: HELP IN BUILDING A BIPED

Projects Discussion and Showcase Robotics
1

Hi There

I'm just starting out in the world of Arduino and Robotics as a hobby and something to do and create.

I've complete several projects already within the Arduino Starter Kit and believe to have good sense of understanding how things works thanks to the Ardunio Project Book which helps explain and illustrates the basic foundations of Arduino and components etc.

Which brings me to now wanting to start tackling a small project to work towards and have found a great beginner project which i would love to get cracking into and that project is "BOB" which is a Biped.

So far i've seen a lot of this projects online and see that there not much to them apart from getting the connection right and the components.

Please see attached youtube link of the project i want to start making.

As seen in the link i would imagine people to see this a beginners project.

So in order for me to start this project i'm wanting to use the arduino uno as the main board and custom build the body and shell.

so far this is my inventory list.

1 x Arduino Uno Start kit with Arduino Board and all the basic wires, jumped etc etc.

1 x 9V BATTERY HOLDER WITH SWITCH & 5.5MM/2.1MM PLUG

1 x 10 SETS M3X25 SCREW LOW PROFILE HEX HEAD CAP SCREW

2 x SERVO MOUNT - SERVO PLATE D

5 x 170 TIE POINT MINI BLACK SOLDERLESS BREADBOARD - I BOUGHT EXTRAS FOR OTHER PROJECTS

1 X HC-SR04 ULTRASONIC MODULE DISTANCE MEASURING SENSOR

10 X SERVO MOUNT

1 X ANOTHER BEGINNER KIT FOR ARDUINO - FOR MORE PROJECTS THIS KIT COMES WITH MORE STUFF

1 X 9V BATTERY HOLDER WITH SWITCH & 5.5MM/2.1MM PLUG

4 X SERVO - GENERIC FULL ROTATION (MICRO SIZE) - NOT SURE WHAT SIZE SERVO WOULD BE BEST

4 X SERVO - GENERIC HIGH TORQUE FULL ROTATION (STANDARD SIZE) -NOT SURE WHAT SIZE SERVO WOULD BE BEST

So that is my list thus far i'm still wanting to buy a good speaker to play 8-bit music so if anyone has any recommendations of extra component i require that will be great.

As for the body or shell i will make after i get the skeleton of the robot completed.

if anyone can help me with this as my first project i thank you for your time and really appreciate your help.

Thank you very much

2

That's a really cleaver design. It's also a great platform to build upon. Starting with just the four servos, you could first build it so that you have the user control each servo directly from separate inputs. Then build in routines so the user can send forward and reverse commands and let the arduino work out the details.

An infra red remote control could be used to give the user a wireless interface. You could make this as sophisticated as you like. Add a pair of arms and you could possibly make it able to climb ropes too.

3

Hi KenF

Thanks for your reply.

Are you able to tell what a shield is and how it is used?

For i've seen some other build use a "Shield" in order to wire up the components.

So just a quick question would i need a shield for this or can the Arduino uno be able to handle all the inputs?

I also want it to play 8bit music from a speaker also will the arduino uno be able to handle that aswell.

As i'm still waiting for my parts to arrive in the mail i'm still studying what would be required in order to build it according to the youtube clip i have linked in above.

Thanks again

4

So, What's a shield?

A shield is just a separate board that's designed to sit on top of your UNO. They come in many forms. So, for instance, you could get a shield with a display built onto, or another shield would have an ethernet controller built in etc..

Just about anything that you can attach to an arduino, you can bet that someone has built a shield for it already. When it comes to your servos, however, I don't think you need a shield. The PWM signal you could just attach directly to the relevant pin on your arduino, while the power leads, you'd connect directly to their own power source (probably a battery pack).

Something you might find handy, though, would be a prototyping shield. This allows you to solder your own components in place and is therefore more secure than having components rattling around on a breadboard.

Something like one of these.

5

awesome thanks so much.

i just purchased two prototyping shields can't wait to start modelling it up and i'll definitely post some updates on this starter project when i receive my equipment.

Thank again for all your help!

6

Basic biped projects.

http://davidbuckley.net/DB/Inspire.htm

7

In robotics, especially with walkers, you definitely want to start with something simple. You'll learn an enormous amount by time you've got it going. Then, you can use that knowledge to bootstrap your next project - like something more complex.

Zoomkat beat me to suggesting David Buckley's website. David's Ambler and Bambino bipeds are very similar to the initial youtube link. Most other people have probably gotten their ideas from David's stuff.

UNOs are definitely not the best boards to try and interface with servos and sensors, but you can make good interfaces using a protoshield. There are some shields that already have 3-row headers on them that are easiest for robotics-style interfacing. The 3-rows are usually wired as signal - power_buss - ground_buss.

The one thing of importance is, you cannot run servos off a small 9V battery. First, you need 4.8V-6V power, although a bit more is usually not a problem. Secondly, the little 9V batteries will go flat in a few minutes running servos. Figure typical 300-1000 mA current per "standard" 44 oz-in servo, depending on load.

About the best thing [other than expensive Lithium batteries] is to use rechargeable NiMH AA-cells, and 6 in series will give you nominal 7.2V, which is ok for most servos. They come in 2000-2500 mAhr ratings, which should run your biped for 30-60 minutes.

8

Loki parts patterns.

LokiBody2.jpg
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LokiFeet.jpg
LokiFeet.jpg1231×881 91.3 KB

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Main page, Bambino is the last in the list and similar to the original youtube video, Loki is a very different walker, but also cool.

10

Thanks you so much ZoomKat & Oric_dan for your knowledge and helping me more understand what is required for this project i have been researching a lot already :slight_smile:

At the moment i have been looking at the best way to battery power the arduino Uno and as well as the 4 servos that i will be running. And will definitely take your advice.

Currently i'll been testing out a servo with the 9V Battery and i think its way too much current which i think makes the servo go crazy and won't respond to my arduino's code of having there servo rotate 0 to 180 and vice versa. Which instead rotates from 0 to 180 and gets stuck still rotating forward :frowning:

However I read about a motor shield that can be used on top of a Arduino Uno which states to make life easy with power voltage and wire configurations

Would that be more sufficient in running the 4 servos?

I found this one by Adafriuit which looks amazing and very promising

11

Currently i'll been testing out a servo with the 9V Battery and i think its way too much current which i think makes the servo go crazy and won't respond to my arduino's code of having there servo rotate 0 to 180 and vice versa. Which instead rotates from 0 to 180 and gets stuck still rotating forward

What is the voltage rating of your servo? You may be lucky you haven't ruined it. Below is a basic diagram of how to wire a servo to an external power supply and connect the servo to the arduino.

servo-wire.jpg

12

I thought so too :frowning: when i was testing it out.

Its a Mirco Servo that came with the starter kit.

Theres a sticker and looks like it says 5V :frowning: and been running 9v battery to it.

This is a picture of my setup i used not plugged in of course :slight_smile:

13

Added Picture

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14

I already described the best way to power the servos. 9V battery is not it.

The adafruit stepper motor shield is actually made to run motors, not servos. It just has a couple of connectors wired on to plug the servos into. You'd be better off with one of the sensor shields I referenced before, because you can connect both servos and sensors. With the adafruit shield, you'd be wasting the primary circuitry on the board - which is to the motor drivers.

15

no problems, can i use the 9v battery to power the Arduino Uno through the barrel jack?

Or is 9V battery is again not right to power up the arduino.

Thanks again for all your help.

16

The 9V battery is fine for the Arduino, and should last for many hours. If you power Arduino from 9V, then you only need 4/ea AA-cells in series to power the servos.