Final project: Spiderbot

1. Why this project?

Spider-man is my favorite superhero since I have memory, I love cosplaying as him and visiting childrens in hospital or walking around the city taking pictures with children and making sure they have a great memory with his favorite superhero and the most important thing, e insperes me to be a better person and never giving up.

I always wanted to have a realistic spiderbot but the ones that are available are expensive for what they can do; most just move on wheels at the bottom, with the legs being purely decorative. The most realistic one in terms of movement is the Disney version, as it does appear to have moving legs, but it moves very slowly, not quickly like a real spider.

My main goal is to create a spiderbot that moves like a spider and that can be controlled with phone. As a second goal but not main one is to integrate a system that allows the spiderbot to follow you like if it was a mascot.

As I would like that my spiderbot moves quick I would use the mechanism of image 4 since is the one that allows a quick response because it will be controlled by servomotors. For the Communication I'll use Wi-Fi because it it has a greater communication range than a Bluetooth module due to that the ESP32-S3-WROM-2 will be perfect as it already has integrated a Wi-Fi and allows me to have free pins if I want to add more sensors or modules to the spiderbot. Last but not least a tiny speaker that make a noise so you can notice him.

1.1 Sketching

I based the appearance on the 4 images that were shown, mixing it because they have elements that I do like the web pattern (1), colors (2), face and legs design (3) and the mechanism (4), adapting these references to the design I would like my spiderbot had.

Systems integrating the project

• Motion: Servomotors
• Microcontroler: ESP32-S3-WROM-2
• Communication: Wi-Fi and phone
• Noise generation: Speaker

2. Body design

This first design will be used as the basis for everything, because at the beginning of any robotics project it is important to maintain simple geometric figures at the beginning in order to later make redesigns based on that simple figure but which can integrate aesthetic design.

2.1 Body sketch

First I sketched the area of the body by putting inside all the components that I've considered the spiderbot will have.

2.2 Body in SolidWorks

After that I measure the ratio to sketch the body on SolidWorks, measuring a ratio of 7.5 cm; then I added the walls where the servomotors legs will be attached.

Here is how the version 1 body looks like, is important to notice that the body has holes to use screws to attach other pieces (I will explain this pieces next) of the legs and also the servomotors. I will use M3 screws.

2.3 Servo adapter

This piece fits on the gear of the servomotor, to allow him to move other pieces.

2.4 Coxa-femur

This piece links the coxa with the femur, attaching to the servo adapter, serving as a part which helps to maintain the rotation of the coxa servomotor.

2.4 Femur box

This part might seem unnecessary since the tibia and femur servomotors can be joined with just a screw, but this isn't sufficient because that connection is weak due to the constant movement of the servomotors. Therefore, its purpose is to provide rigidity and stability to the femur.

2.5 Tibia

This part is the complete tibia only attached woth the servomotor gear and its respectively screw. I designed it like a oval, because I want to test if it can have this geometric shape for the final design of the legs.

2.6 Assembly

2.6.1 In SolidWorks

I then assembled the complete body to see if the pieces were designed correctly. My recommendation is to have the piece that will be fixed, in my case the body, and then design and test every piece in the assemble to make the corrections at the moment.

2.6.2 In physical

I 3D printed the pieces, buy some M3 screws and start linking the pieces; starting from the inside out.

I tested the legs manually and they all moved correctly, so when the servos are powered they should move fine.

In this video I show the 3 degrees of freedom that one leg (coxa, femur and tibia) has, therefore, each leg has the same degrees of movement.

3. Coding

For the code, at the moment I will just test legs from both sides. The legs will be connected to a servomotor module having one per side. At this mooment I will only prepare a routine for them to move the legs in a specific order.