Hex-Hex Fruit

ESP32 Development Board

mpu-6050 gyro and accelerometer

Buffer / Line Driver, 74HC126

Lithium Battery 7.4V 8.4V 18650 Charger & Protection Board

LewanSoul LX-16A Full Metal Gear Serial Bus Servo

Resistor 10k ohm

Microswitch, IP67

PlatformIO IDE

Bantam Tools Desktop PCB Milling Machine

Hot Air Station, Industrial

DC Power Connector, Straight

Jumper wires (generic)

General Purpose Transistor NPN

Drill / Driver, Cordless

Arduino IDE

Solder Wire, Lead Free

Laser cutter (generic)

Connector Adapter, DC Power - 2.1mm

18650 lithium Battery

Solder Flux, Soldering

Soldering iron (generic)

12V 20A LED Light Rocker Toggle Switch

<p >The story</p><figure><img src=https://projects.arduinocontent.cc/efbc9fa3-9376-41d6-ad45-5d6d3cb73687.png /><figcaption> </figcaption></figure><p ></p><div id="gallery"><img id="gallery" src=https://projects.arduinocontent.cc/8f664bad-f23e-4614-8e0d-285b94edf055.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/da466796-8b4d-4334-a232-6132e51f15bd.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/045d1814-6f8b-4e00-a5e2-fee9ab6f98b7.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/acd23574-967e-405f-be26-3dad5d40ee76.gif /><figcaption>Hex-Hex Fruit in action</figcaption><img id="gallery" src=https://projects.arduinocontent.cc/9fef262f-7ac0-4e63-a7ba-53072ef39fda.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/396e3371-3088-47ad-b6d1-33b479c28608.gif /><figcaption> </figcaption></div><h3 >Introduction</h3><p >Hello everyone! Aim of this article is to explain how to make hexapod robot from scratch. Robot will be able to do various kind of movements and it will be able to balance its body on uneven terrain (keep body in horizontal plane). Let's divide whole project in 3 main parts:</p><ul ><li >mechanical side</li></ul><ul ><li >hardware</li></ul><ul ><li >software</li></ul><p >and go through all 3 of them in details.</p><figure><img src=https://projects.arduinocontent.cc/b1d695d2-5757-4051-bc2b-2483c643ad83.JPG /><figcaption> </figcaption></figure><p ><strong >Mechanical</strong><strong >side</strong></p><p >In order to assemble chassis of robot we used wood, organic glass and metal brackets. Let's start with the main frame, we used wood and laser cutter to make upper and lower parts of body and then connected them using metal brackets(black ones came with servo and silver ones we made by ourselves).</p><figure><img src=https://projects.arduinocontent.cc/2fd387ca-d662-4960-86c1-457d1437f6c6.jpg /><figcaption> </figcaption></figure><p ></p><figure><img src=https://projects.arduinocontent.cc/e2b7f1f1-e9e9-42c2-bf3d-1d33b9c260e1.jpg /><figcaption> </figcaption></figure><p >In order to make legs we connected 3 servos using brackets.One end of it is connected to mainframe and second end to organic glass. glass was also cut on laser and after it we bent it using heat gun(see process below), which gave it curved like shape. After bending it we connected two parts using wood cube and glue.</p><figure><img src=https://projects.arduinocontent.cc/8d1375f6-f2cb-4eea-9ce9-78d2556eb3e1.jpg /><figcaption>Legs</figcaption></figure><p ></p><figure><img src=https://projects.arduinocontent.cc/9801af5e-abff-4152-9b3f-3f8d1ef1885c.gif /><figcaption>Heating process</figcaption></figure><p ></p><figure><img src=https://projects.arduinocontent.cc/06afba6a-ea53-4f4a-bbd8-ab05a3c500f5.gif /><figcaption>Bending process</figcaption></figure><p ><strong >step</strong><strong >check</strong></p><p >In order to detect when robot would touch on the ground during walking we added micro switch in every leg. Switch is connected on a custom made bracket. we drilled hole in the wood which connects 2 parts of leg and inserted metal rod and spring in it. Ground  part of the rod is coated with a polyurethane (this increases friction on the ground and makes robot more stable) and upper part of rode is connected to micro switch and presses it when leg touches the ground.</p><div id="gallery"><img id="gallery" src=https://projects.arduinocontent.cc/9e9ae393-93aa-4a18-8ef4-afa1d470544b.JPG /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/c8fc36d5-e0ef-4732-86b5-b6826ef8b9e6.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/024f678d-a0a5-4c71-aa26-a580f611eaa5.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/f8ddafb3-abeb-494c-a1e6-d9f7bd497594.jpg /><figcaption> </figcaption></div><h3 >Hardware</h3><figure><img src=https://projects.arduinocontent.cc/09030188-4a24-48ea-b4a4-68fe2597a513.JPG /><figcaption> </figcaption></figure><p ><strong >main</strong><strong >board </strong></p><p >we created circuit board which supports connection with esp32, mpu-6050 and servo motors. Servo's, which we have in this project, use half-duplex UART for communication with micro controller to achieve this type of communication we used 74hc126, transistor and few resistors(for NOT gate).</p><figure><img src=https://projects.arduinocontent.cc/d7526382-de89-4e00-b566-2373aabd08b0.png /><figcaption> </figcaption></figure><p ></p><div id="gallery"><img id="gallery" src=https://projects.arduinocontent.cc/5b6e0206-efd4-47c2-8a3c-d5dec90e1a91.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/cea31f97-3498-4068-ab65-7d297fefe2b2.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/4ad853b5-fd4f-4da9-8d27-4356a849d818.png /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/71d87575-ce96-4273-b229-3c318936edc9.gif /><figcaption> </figcaption></div><h3 >Power</h3><p >Circuit board is receiving average 7.4V from the input which goes servo motors, after that voltage is reduced to 5v using dc->dc converter to supply other components of circuit(esp32, mpu-6050...). In order to deliver this power we used 4 3.7v lithium batteries and connected them to little charging board as it shown below:</p><div id="gallery"><img id="gallery" src=https://projects.arduinocontent.cc/0027589c-101c-4080-8676-a5175bea170a.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/b0aa0972-2e85-49d5-9f01-a47d3e51ca7a.jpg /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/d7e6cdab-c57b-4b94-b84e-5ffd097fc503.jpg /><figcaption> </figcaption></div><p >batteries are connected to charging port and switch, which delivers power to main board.</p><figure><img src=https://projects.arduinocontent.cc/7b25af91-49b4-4e16-af47-8f6d8dbebb62.JPG /><figcaption> </figcaption></figure><h3 >Software </h3><p >You can use Arduino IDE or platform IO to compile and upload code to micro controller. Code is written in c++ and is divided in couple of libraries, which allows user to replace some parts of project by changing only corresponding library file. Note that code is still in work in progress so it is not perfect.</p><figure><img src=https://projects.arduinocontent.cc/fc014776-7021-4547-893b-a9fafc52d62f.png /><figcaption>Mobile app</figcaption></figure><p >We used mobile phone to connect with esp32 using bluetooth application created specially for this project. It gives user ability to move robot and switch between few modes. It also outputs voltage present in servo motors which is good battery indicator (8.4v - fully charged, 6.4v - discharged).</p><h3 >Balancing</h3><p >robot is using  PID library to keep its body in horizontal plane, you can see what this process looks like below:</p><div id="gallery"><img id="gallery" src=https://projects.arduinocontent.cc/6289b567-d88e-4580-880c-a7b3924cd8bc.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/4d340767-c066-45fe-8ba2-efb95e14e67f.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/a659ccce-5bbd-4755-a68c-eeb6b9ff9256.gif /><figcaption> </figcaption><img id="gallery" src=https://projects.arduinocontent.cc/62d39d37-c5ad-4836-a8f0-d63084b81705.gif /><figcaption>Balancing</figcaption></div><h3 >Conclusion</h3><p >This project took me 1 year to make and it's still far from being perfect. It is still in work in progress so code will get updates. If any of you are interested in robotics you should find this article interesting, because it basically divides whole problem into much smaller problems which you can use individually for your projects. Write me if you will have any questions.</p><p >Good Luck!</p><figure><img src=https://projects.arduinocontent.cc/ab6743d6-6771-4cfb-9f64-ca655637a2e2.JPG /><figcaption> </figcaption></figure><p ></p>

Body 

motherBoard

esp32 Code repository

Hex-Hex Fruit

Let's build hexapod robot with some neat features!