Friday, November 20, 2015

Arduino Powered Hexapod/Spider 18 DOF Robot

My next project is a six legged robot.  I look at these projects that are all using an Arduino Uno and servos like they are a modern day version of the "erector set" that I played with as a kid.  This is a more economical way to build these various projects instead of buying several expensive kits.  Basically I am using the same parts to make all of the following projects:
5,9,13,17 DOF Humanoid robots
14 DOF Dog robot
17 DOF Dinosaur robot
18 DOF Spider robot

I have looked at several hexapod designs and so far I have been able to reproduce the body using standard parts.  The other designs use two custom plates spaced about two inches apart.  My design uses:
4 - Angled "U" brackets
2 - Straight "U" brackets
2 - Waist brackets
4 - Straight brackets
2 - "L" Shaped brackets.

Here is a top view of my design for the hexapod body.

This next picture is a side view of the hexapod body: 

So now to collect at least 18 servos to make it work.

I decided to make my own lower legs.  I used a picture from a kit on ebay and blew it up to the actual size.  Then I cut it out and used it as a model.  These legs were cut out with a hand held jig saw.  They did not look that good in clear plastic so I painted them black.

This is after two coats of paint.

This is what they look like on the assembled spider.  They are still a little rough.

 Here is how I assembled the servo mounting brackets.  Then I added the servos and then mounted them on the robot.

 The Arduino mounted real nicely using some of the existing holes in the bracket.

Here is the completed spider as far as the mechanical assembly.

Monday, November 9, 2015

Walking "Dog" and "Dinosaur" 17 DOF robot from Humanoid robot kit.

I plan on making some more creations besides the 9, 13, and 17 DOF humanoid robots from the robot kit.  The next one is this 14 DOF "Dog" robot.  This is actually the third revision and there will be more to come.  As you can see I have had a hard time with attaching the "tail".  The "Mouth" is a robot hand or it was....

He is starting to work.  Here is the latest picture of him.  He lost his "feet" and has a more solid rear end.
And now for his first video appearance.

The next thing to do is to add a tail and make him into a dinosaur.

Here is the dinosaur video.

He has now grown to three feet long and has LED eyes.

Here is his second video with greatly improved software.

Friday, October 9, 2015

Walking "Humanoid" Robot found on eBay part 3 with 9, 13, and 17 DOF

After not having a lot of success with a more complex robot I went backwards and built a 9 DOF humanoid robot.  Here is a picture of that robot.

Here is the video of him walking.

Up next is the 13 DOF humanoid robot.

Here is his video.

Here is his servo array to make him walk forward.

int walkf[6][6] = {
// 0    1    2    3    4    5
{ 80,  80,  80,  85,  90,  90}, // Left Ankle
{ 90,  80,  70,  70,  70,  80}, // Knee
{ 90,  80,  70,  70,  70,  80}, // Hip
{100, 100, 100,  95,  90,  85}, // Right Ankle
{ 90,  90,  80,  70,  70,  80}, // Knee
{ 90,  90,  80,  70,  70,  80}, // Hip

I still cannot get a 17 DOF robot to work very well.  My servos are too weak for the weight! Do not buy the MG995 or MG945 servos except for the arms (or for a 9-13 DOF robot). I have burned some up trying to power the 17DOF robots legs. I am thinking of trying the MG958. Anyone know if that servo has enough power?

Here is some more Information that I have discovered about servos and robots.

Be sure the servo that you buy is not a cheap imitation.  This can be detected by the seller hiding the manufacturer name or misspelling the manufacturer name.  A common example would be “Tower Pro” (real) or “Towerd Pro” (fake).

This is my new rule of thumb for making humanoid, as in 2 legged robots.  The problem is that the more the servos (and their connecting hardware) the more the robot weighs. 

The leg servos of a 5-9 DOF Humanoid robot should handle 100 oz. inches of torque. 
The leg servos of a 10-15 DOF Humanoid robot should handle 150 oz. inches of torque.
The leg servos of a 16-20 DOF Humanoid robot should handle 200 oz. inches of torque.
Here is the video of the 17 DOF humanoid robot.

Wednesday, September 16, 2015

Walking "Humanoid" Robot found on eBay part 2

I am back to working on the walking humanoid robot after writing another book.  First I had to make an Arduino Shield to control the servo's.  Here is a video testing the servo shield.

Next is to connect it to the robot and get those servo's working.  I am using an IR remote control to test his movements.  This is a picture of the front view of the setup.

Here is the back view.  The arduino has been mounted in place for this picture.

Here is a video of me testing out the robot servo's.

Here is a second video with most of the servo's working and they are now "zeroed".

In spite of the really bad servo's he is taking his first steps.

Here is a two servo per leg version of the robot.

Here is the code for the two servo per leg robot in video 4.

void StepForward(){  //Moving Left Leg Forward
  servo1.write(75);  //shift weight to left ankle
  servo3.write(60);  //right ankle kicks weight over
  servo3.write(70);  //free ankle lifts
  servo2.write(110); //left hip
  servo4.write(120); //right hip
  servo1.write(90);  //level leftt ankle
  servo3.write(90);  //level right ankle
  servo1.write(115);  //Shift weight to right ankle
  servo1.write(110);  //free ankle lifts
  servo2.write(70);  //left hip
  servo4.write(60);  //right hip
  servo1.write(90);  //left ankle - back to home positions
  servo2.write(90);  //left hip
  servo3.write(90);  //right ankle
  servo4.write(90);  //right hip

Friday, August 28, 2015

DIY Arduino Uno powered 5 MSPS Oscilloscope.

I have been wrining a book of "Arduino Oscilloscope Projects".  In this book I show 4 different LCD's, 5 different Analog to digital converters, and 3 different analog front ends.  The code has greatly improved with a "gain" in software feature.  I have written the code for a 1.8 SPI TFT screen as well as for a 2.4 inch or 2.8 inch ILI9341 Screen.

Here is what the 1.8 inch screen looks like.  On the bigger screens the sample time in MS is located under the other text fields on the right side.

Here is what the assembled oscilloscope looks like so far.

This is a picture of the main board without the LCD screen.

This is the front cover.  I need to wire the cover to the main board next.

Here is the finished project.

Here is a video of the project.

Thursday, August 20, 2015

Chestnut Ridge Park - The Eternal Flame

A few days ago we walked to the Eternal Flame at Chestnut Ridge Park.  Here are some pictures.
This is a chipmunk that watches us on our walk.

When you get down to the creek bed this is what it looks like.  You need to climb over some logs.

This is looking back up the side of the creek bed. 

 There are lots of warning signs....

Finally we made it to the eternal flame.