I always wanted to make a quadruped robot of my own and the Minecraft contest was a good excuse. Besides, I really wanted a Creeper 'pet'.
In this Instructable I'll share how I made it and give you a guide if you want to make your own.
I assume you have had some experience with electronics, but if you have any questions please feel free to ask on the comments and I'll do my best to answer them.
Reading RC receiver with Arduino: https://ryanboland.com/blog/reading-rc-receiver-va...
PCA9685 Tutorial: http://www.naylampmechatronics.com/blog/41_Tutoria...
Step 1: Materials
9x MG90S servos
18x M2 nuts and bolts
8x M3 bolts
4x 45mm M3 standoffs
4x 25mm M3 standoffs
1x Arduino UNO
1x PCA9685 servo controller
1x Battery (I used a 2 cell 7.4V 1000mAh 20C LiPo)
Optional: A battery monitor to prevent over-discharge
1x Step-Down Regulator
Optional: A switch to disconnect the battery from the regulator
1x RC receiver and controller (I used a Eachine iA6 Rx and a Eachine i6 Tx)
Jumper cables (M-M, M-F)
Superglue to glue some of the 3D parts together
Velcro and anti-slip sticker. I used some I got from the supermarket from 3M brand.
You'll also need some Green filament to print the rest of the parts and a bit of black filament for the face.
You'll need a screwdriver for all your screws. A voltage meter to calibrate the regulator.
You'll also need a soldering iron and a bit of solder.
Step 2: Print the Parts
All of the parts were designed in Fusion 360.
You'll need to print the following in the specified quantities:
2x Foot A
2x Foot B
2x Leg bracket A
2x Leg bracket B
1x Base plate
1x Mid plate
1x Head bottom
2x Head sides
1x Head front
1x Head top
1x Head top cap
1x Head back
1x Head door
1x Face (in black color)
Step 3: Assemble the Legs
The easiest way to assemble the legs is by first screwing the servo arms into the feet and the leg brackets. Use the screws that came with the servo.
TIP. Taper the servo arms holes before attaching them to the 3D printed parts.
After you attach the servo arms, attach the foot servo to each of the leg brackets using the M2 screws and nuts.
Then attach the leg servos to the base plate, again with M2 screws and nuts.
Finally, attach the leg brackets to the leg servos in the base plate and then the feet to the feet servos.
Note: Route the leg servos' wires through the holes in the base plate.
Optional but recommended: Add anti-slip stickers to the bottom of the feet!
Step 4: Assembe the Torso
Attach the 4 25mm stand-offs to the base plate using 4 M3 screws.
Attach the 4 45mm stand-offs to the mid plate using 4 M3 screws.
Assemble mid plate on top base plate using 4 M3 screws and route servo wires through the holes.
Assemble the head servo to the torso.
Assemble torso on top of mid plate using 4 M3 screws and route servo wires through the holes.
Step 5: Assemble the Head
Using super-glue assemble the head pieces as shown in the picture and video.
After the head pieces are glued together, route the servo wires through the holes and screw the head to the head servo.
The "head top cap" and "head back door" prints close out the holes in the head. These two holes are meant for easy access to the electronics.
Step 6: Electrical Connections
Please follow the electrical connections as shown in the schematic.
You'll need to trim the step-down regulator to provide 5V (or the voltage your servos work with). Use a screwdriver and a voltage meter to do this.
You might need to splice some jumper cables together. Use solder and cover the splice with electrical tape or heatshrink.
I arranged the electrical boards inside the head as shown in the picture.
I used velcro tape to fix them to the head walls.
Step 7: Calibrate Servos
The creeper's movement only require two different positions for each servo. We'll calibrate those two positions now.
Upload the calibrate_creeper script (see attached) to the Arduino and open the Serial Monitor.
You'll manually position the robot as shown in each picture and take note of the servo values for each one.
To move a servo using the script, use keys Q/A, W/S, E/D.
To change which servo you're moving, use the Z/X keys.
To show the current servo values use any other letter, such as L.
Once you move the servos to the correct position, take note of the values and update the pos0 and pos1 arrays in the code.
After you update the arrays, you can re-upload the code to the board and use the 5-9 keys to preview the walking gaits.
Step 8: Play
Open the CREEPER_RC code and update the pos0 and pos1 array with the ones from the previous step.
Upload the code, turn on your RC transmitter and play!
Step 9: Future
In the future, I'd like to add more functions to the Creeper, such as:
Add a speaker to make sSsssSsssS and exploding sounds!
Add an RPi and a camera to get Creeper vision.
Please let me know if you have any cool ideas about future additions.
This is the end of this Instructable. Please let me know your comments and questions.
Thanks for reading.
Second Prize in the
Minecraft Challenge 2018