Sixteen-pede: Artificial-Arthropod-Crawler-Pet

Insects and other simple animals have always amazed me - just because they get by with a fraction of the nerve cells of a human being and yet have survived on our planet for millions of years in some cases.

Arduino is such a simple brain. And also one that I can understand myself. Years ago I already built a kind of lizard with a Raspberry Pi Zero. The "nervous system" was completely overqualified.

So how do you build a "living thing" with a few artificial nerve cells, a sensor and a couple of servo motors? Centipedes are great, you could watch the coordination of their legs for hours. I can't do a hundred legs, but I can do sixteen.

No 3D printer needed!

9x servo SG90 motors

ESP8266 Wemos D1 (or D1 pro) or Arduino nano

VL53L0X Time-of-Flight Ranging Sensor

5V LiPo battery

Wire, soldering iron, glue gun, wooden strips (approx. 1 cm high)

Paper clips or wire (Ø 1 mm)

Heat-shrink tubing (2mm, 70mm)

(slide switch)

Align servos: Before mounting the legs, the servos should be set to center position (90). This is what the script sixteen-pede.ino does for us. But we'll get to that later in step 5.

If you would just line up the servos, the sixteen-footer would only move back and forth. (I tested a few locomotion options:

a) Without angles to each other.

b) With hinges between the servos.

c) With angle and rigid attachment. )

That's why we build in a forward movement through an angle of about 30 degrees.

The servos are connected with a piece of wood in between with hot glue as described in the picture. On the sides of our robot we glue battens for stability.

We separate the three cables of each servo and remove the connectors of Gnd (brown) and Volt (red).

We start the parallel circuit connections at the front with servo 1: Shorten the wires as needed and solder the ground of one servo to the ground of the next servo and insulate the connections with heat shrink tubing or tape. We do the same with the 5V wire. Continue until the last servo. We connect the last two ends to Wemos D1 with 5V (red) and Gnd (brown).

To have less mess we glue the wires closer to the body.

Leave the orange data lines untouched, they will be connected to the ESP8266 later.

The head servo is also connected to the other servos with Gnd and 5V, the data line additionally with the data line of servo 1.

Connect the head servo with a small arm on the body as shown in the picture. Use small pieces of wood for the assembly.

The VL53LO sensor is attached to the front of the head with adhesive tape, and the four cables are connected to the ESP8266.

[I first tested everything with pins and connectors. Later, of course, everything was soldered to save space.]

Servo - Wemos - Arduino sketch

------------------------------------------------------------

Leg 1 = Rx = 3 (Leg 1 and head!)

Leg 2 = D3 = 0

Leg 3 = D4 = 2

Leg 4 = D0 = 16

Leg 5 = D5 = 14

Leg 6 = D6 = 12

Leg 7 = D7 = 13

Leg 8 = D8 = 15

Sensor

Vin = 3.3V

Gnd = Gnd

SCL = D1

SDA = D2

You better use plugs that you can pull off the sensor. Sometimes the sensor causes problems while flashing.

Now you can upload the file sixteen-pede.ino to the Wemos and try out the sixteen-footer in automatic mode. (Better unplug the sensor!)

The robot decides independently at a distance of 40 cm to which side it will go. Unfortunately, walking backwards is not possible.

You can find good instructions for uploading to Wemos D1 here:

https://www.instructables.com/Nodemcu-Mini-D1-R1-for-Beginner-ESP8266-Bink-Wemos/

When you start the sixteen-pede, all servos first go into the center starting position (90) for 2 seconds, than it crawls. Quickly remove the power supply before the 2 seconds have passed. Then you can mount the legs.

Thread paper clip or wire through double servo arms as shown in the picture. Cut the wire legs on each side to exactly the same length (approx. 4 cm + 1cm).

Fold the last centimeter of the wire to make a foot.

Cut sixteen 10 mm long pieces of heat shrink tubing and put them over the feet, the tube must protrude a little. Shrink the tube with the hot soldering iron.

Mount the legs to the servos, Check that the legs are the same length and shape on each side.

You can still add a slide switch or give your sixteen-pede a better look.

For a skin I used a heat shrinkable hose with diameter 70 mm.To do this, you take off the legs again, put the tube over the robot and shrink it carefully with a hair dryer. Then gently cut out the servo arm connectors and remount the legs. In addition, the heat shrink tube gives more stability.

Connect the battery and

have fun with your new pet!