The upper torso and hip of a humanoid robot are critical components for structural support, mobility, and interaction with the environment. They provide the framework for mounting arms, shoulders, and the head while enabling complex movements such as bending, twisting, and stability control during locomotion.
1. Functional Objectives
The humanoid robot’s upper torso and hip must:
- Provide Structural Integrity: Support the head, arms, and torso components, as well as external loads.
- Enable Mobility: Allow movements such as bending, twisting, and side tilts for realistic human-like actions.
- Integrate with Other Systems: Serve as a base for mounting sensors, actuators, and other subsystems.
- Facilitate Balance: Maintain dynamic and static balance during motion and interaction.
- Allow Modularity: Enable easy assembly, maintenance, and upgrades.
2. Key Components
| Component | Function |
| Frame Structure | Provides the skeleton-like support for the torso and hip. |
| Actuators | Drive movements like bending, twisting, and balancing. |
| Sensors | Monitor position, torque, and orientation for feedback control. |
| Power Transmission | Transfers power from actuators to joints. |
| Cooling Systems | Prevent overheating of actuators and processors. |
| Control Systems | Process sensor data and actuate movements. |
| Connectors | Attach the torso to the arms, head, and lower body. |
| Encasement | Protect internal components and enhance aesthetics. |
3. Upper Torso Design
3.1 Structural Design
- Frame Material: Use lightweight materials like aluminum or carbon fiber to reduce weight without compromising strength.
- Mounting Points: Include brackets or slots for attaching arms, shoulders, and sensors.
- Compartments: Design compartments for housing processors, batteries, and wiring.
3.2 Mobility
- Twisting: Include a rotary actuator for yaw motion (~±45°).
- Bending: Use linear or rotary actuators to enable forward/backward tilting (~±30°).
- Side Tilts: Add a degree of freedom for tilting side-to-side (~±20°).
3.3 Integration
- Sensors: Include IMUs for orientation tracking and force sensors to monitor loads.
- Cooling: Add ventilation slots or small fans for heat dissipation from processors.
4. Hip Design
4.1 Structural Design
- Load-Bearing: Design to support the upper body and transfer weight to the legs.
- Material Selection: Use high-strength materials like titanium or reinforced aluminum for durability.
- Joint Design: Incorporate bearings and hinges for smooth motion.
4.2 Degrees of Freedom
- Pitch (Forward/Backward Tilt): Enable walking, sitting, and leaning movements.
- Roll (Side Tilt): Allow balance adjustments and lateral motions (~±20°).
- Yaw (Rotation): Add a rotary actuator for twisting motions (~±30°).
4.3 Actuation
- Linear Actuators: For precise and smooth bending and tilting motions.
- Hydraulic or Pneumatic Actuators: For high power and load-bearing capacity.
- Electric Motors: Use BLDC or servo motors for lightweight and energy-efficient operation.
4.4 Sensors
- IMU (Inertial Measurement Unit): Tracks orientation and angular velocity.
- Force/Torque Sensors: Detect loads on the hip joint for dynamic adjustments.
- Rotary Encoders: Measure joint angles and motion speeds.
5. Power and Control Systems
- Central Processor: Place a microcontroller (e.g., STM32, Raspberry Pi) or AI processor in the torso for real-time control.
- Power Distribution: Integrate a power bus for efficient distribution to actuators and sensors.
- Control Software: Use ROS or custom algorithms for motion planning and feedback control.
6. Cooling Systems
- Passive Cooling: Include heat sinks and thermal vents in the torso.
- Active Cooling: Add small fans or liquid cooling systems for high-power actuators.
7. Integration of Torso and Hip
- Design the hip as a modular unit that connects seamlessly with the torso frame.
- Use quick-release connectors for easy disassembly and maintenance.
8. Example Subsystems
8.1 Frame and Structural Components
| Component | Description | Example |
| Carbon Fiber Frame | Lightweight and durable frame for torso and hip. | Custom Fabricated |
| Aluminum Brackets | Support joints and actuators. | L-brackets, T-slot Aluminum Extrusions |
8.2 Actuation Components
| Component | Description | Example |
| Linear Actuator | Drives forward and backward tilts. | Firgelli Mini Linear Actuator |
| BLDC Motor | Provides torque for twisting and side tilts. | Maxon EC90 Flat |
8.3 Sensors
| Component | Description | Example |
| IMU Sensor | Tracks orientation and angular velocity. | MPU-6050 |
| Torque Sensor | Monitors force applied to hip and torso joints. | ATI Mini45 |
9. Advanced Features
- Dynamic Gait Adjustment: Use AI to adjust torso and hip motions based on terrain.
- Energy Recovery: Implement regenerative braking in actuators to capture energy during deceleration.
- Redundant Sensors: Include backup IMUs and force sensors for critical functions.
10. Challenges and Solutions
| Challenge | Solution |
| Load Management | Use lightweight materials and distribute loads evenly. |
| Smooth Multiaxis Motion | Integrate PID controllers and high-precision actuators. |
| Heat Management | Include active cooling systems for high-power components. |
| Signal Interference | Use shielded cables to minimize electromagnetic interference. |
11. Tools and Software
- Design Tools: SolidWorks, Fusion 360 for structural design.
- Simulation Tools: Gazebo, MATLAB/Simulink for motion analysis.
- Programming Frameworks: Python, C++ with ROS for system integration.
Conclusion
The upper torso and hip of a humanoid robot are central to its functionality, providing support, mobility, and interaction capabilities. By carefully integrating structural design, actuation, sensors, and control systems, these components enable realistic and efficient robotic movement for various applications.