# An energy efficient 3D printed leg for bio-inspired hexapod robots

Ilya Brodoline, Stéphane Viollet, Julien Serres

► To cite this version:

Ilya Brodoline, Stéphane Viollet, Julien Serres. An energy efficient 3D printed leg for bio-inspired hexapod robots. Journée des Jeunes Chercheurs en Robotique 2019 (JJCR’19), Oct 2019, Vittel, France., 2019. [hal-03326480](https://hal HAL Id: hal-03326480)

https://amu.hal.science/hal-03326480

Submitted on 26 Aug 2021

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<figure><img src="image_1.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
## CONTEXT

Servomotors are the mostly used actuators for small electric legged robots. Is it possible to design a new actuator, optimized for small hexapod robots?

[1], [4]

<figure><img src="image_2.png" /></figure>

### Heat-resistant

In opposition to compact servomotors, this actuator has a **large structure** in favor of **heat dissipation**.

## MECHANICS

### Design

#### New 3D printable leg

Mostly composed of **3D printed parts**, this new leg has a reduced price of manufacturing.

In association with some aluminium parts, the total mass equals to **300 grams**.

Materials : SLA resin, PLA, Aluminium.

#### Energy saving mechanics

Screw-nut mechanism is **irreversible**.

Therefore, there is no energy consumption when a joint is not used.

### Servomotor vs Irreversible Joint

<table><thead><tr><th></th><th>Servomotor (ex : AX18-A)</th><th>Ir. Joint</th></tr></thead><tbody><tr><td>Price</td><td>&lt;100€</td><td>~20€</td></tr><tr><td>Speed</td><td>100 rpm</td><td>~50 rpm</td></tr><tr><td>Torque</td><td>1.7Nm</td><td>3.6Nm</td></tr><tr><td>Passive State Power</td><td>3.6W</td><td>0W</td></tr></tbody></table>

## BIOLOGICAL ASPECTS

### Bio-inspired leg

#### Sized from Cataglyphis Fortis ant

To provide a reliable leg structure able to be used by biologists as a **model for hexapod insect-type robots**.

The joints angles limits and lengths were measured from ants and scaled 1:20. [1], [3]

### Perspectives

#### Force sensors

Next step of the project is to implement **force sensor at strategic location**, most representatives the campaniform sensilla groups. [2]

<figure><img src="image_3.png" /><figcaption>Total mass 2kg</figcaption></figure>

<figure><img src="image_4.png" /><figcaption>Trochanteral receptors
(74% leg receptors)</figcaption></figure>

<caption>Distribution of campaniform sensilla on an insect leg [2]</caption>

#### Bio-inspired hexapod robot

New robot leg should be tested on a **hexapod robot**, to verify its accuracy and efficiency compared to classical servomotor based robot. [1]

<caption>Tibial receptors
(11% leg receptors)</caption>