# Frame and Structural Components

- Page: https://docs.menlo.ai/asimov/0/hardware/frame-and-structural-components
- Section: Asimov › Asimov 0 › Hardware Design
- Previous: [Hardware Design](https://docs.menlo.ai/asimov/0/hardware.md)
- Next: [Joint Design and Actuation](https://docs.menlo.ai/asimov/0/hardware/joint-design-and-actuation.md)

This chapter describes how the Asimov humanoid frame is organized, how major structural modules connect, and why the structural design choices were made.

> [!NOTE]
>
> **CAD Files**
>
> - [Download CAD
>   file](https://github.com/menloresearch/asimov-v0/blob/main/mechanical/ASV0_lowerBody.STEP)
>
> You can view the STEP source file on GitHub and download it from there.

## 1. Asimov Humanoid Structural Architecture

The Asimov 0 legs are organized from pelvis to
the ground, with 12 active degrees of freedom and 2 passive toe joints.
Each leg is divided into pelvis, hip, knee, and foot modules, with 6
active DOF per leg: hip pitch, yaw, and roll; knee pitch; and ankle pitch and
roll.

![alt text](https://docs.menlo.ai/manual/v0/assets/robot_overview.png)

## 2. Structural Breakdown of Main Modules

This exploded view of the Asimov 0 legs shows all parts included in the CAD
files for manufacturing. Components are labeled with indices 1-79, so you can use this
diagram as a checklist to confirm you have all CAD-modeled parts. Fasteners and other
standard hardware (for example, screws, nuts, and washers) are not included.

![alt text](https://docs.menlo.ai/manual/v0/assets/exploded_view_legs.png)
_Figure: Exploded view of the legs with part index labeled._

We separate the robot this into 4 modules: Pelvis, Hip, Knee, and Feet, aligning to the assembly unit.
For each section, we labaled the parts included according to their material. Also for each part we include the indexs labeled in the exploded view for a quick check.

### Pelvis Module

![alt text](https://docs.menlo.ai/manual/v0/assets/pelvis.png)

### Hip Module

![alt text](https://docs.menlo.ai/manual/v0/assets/hip.png)

### Knee Module

![alt text](https://docs.menlo.ai/manual/v0/assets/knee.png)

### Ankle/Foot Module

![alt text](https://docs.menlo.ai/manual/v0/assets/feet.png)

## 3. Joint Structural Packaging

### Joint Coordinate

The picture below shows the joint rotation axis with 0 joint position. The frame convention is blue for z, red for x, and green for y.
![alt text](https://docs.menlo.ai/manual/v0/assets/joint_convention.png)

### Joint Index and Joint rotation range

| Joint Index | Joint Name | Motion Range (rad) | Axis (xyz) |
| - | - | - | - |
| 1 | left_hip_pitch_joint | -2.09 ~ 1.00 | 0 0.70711 -0.70711 |
| 2 | left_hip_roll_joint | -0.79 ~ 0.79 | 1 0 0 |
| 3 | left_hip_yaw_joint | -0.79 ~ 0.79 | 0 0 -1 |
| 4 | left_knee_joint | 0.00 ~ 1.50 | 0 1 0 |
| 5 | left_ankle_pitch_joint | -0.50 ~ 0.50 | 0 1 0 |
| 6 | left_ankle_roll_joint | -0.35 ~ 0.35 | -1 0 0 |
| 7 | left_toe_joint | -0.60 ~ 0.00 | 0.010532 0.99994 0 |
| 8 | right_hip_pitch_joint | -1.00 ~ 2.09 | 0 -0.70711 -0.70711 |
| 9 | right_hip_roll_joint | -0.79 ~ 0.79 | 1 0 0 |
| 10 | right_hip_yaw_joint | -0.79 ~ 0.79 | 0 0 -1 |
| 11 | right_knee_joint | -1.50 ~ 0.00 | 0 -1 0 |
| 12 | right_ankle_pitch_joint | -0.50 ~ 0.50 | 0 -1 0 |
| 13 | right_ankle_roll_joint | -0.35 ~ 0.35 | -1 0 0 |
| 14 | right_toe_joint | 0.00 ~ 0.60 | 0.0074685 -0.99997 0 |

If you want to know more details about the joints, welcome to the next chapter [Joint Design and Actuation](https://docs.menlo.ai/asimov/0/hardware/joint-design-and-actuation.md), where we covered the actuators, ankle and toe joints design.