A body-powered prosthetic arm operates through a mechanical system using cables and pulleys. The user's muscles activate the device, enabling it to move.
Body-Powered Prosthetic Arm Mechanism
A body-powered prosthetic arm functions by translating movements from the body to the prosthetic device. This is achieved through a system of cables and pulleys, similar to how a bicycle brake works.
Key Components:
- Harness: A harness is worn on the upper body, often around the shoulder. This provides an anchor for the cables.
- Cables: These are attached to the harness and run down the arm. They are connected to specific muscles, such as those in the shoulder or back.
- Pulley System: The cables pass through a series of pulleys within the prosthesis, designed to convert muscle movement into limb motion.
- Terminal Device: At the end of the arm, there is usually a tool or claw. This can open and close for grasping objects.
How it Works:
- Muscle Activation: The user contracts specific muscles in their shoulder or upper body.
- Cable Pull: This contraction pulls the cables attached to the harness and the prosthesis.
- Movement: The pulling action moves the different parts of the prosthetic arm, allowing the user to control the device.
- Grasping: By controlling these muscle movements, the user can open or close the tool or claw on the end of the device.
Example
For instance, a user might shrug their shoulder forward to open the terminal device (claw) and relax their shoulder to close it, allowing them to pick up or hold objects.
Pros of a Body-Powered Prosthetic Arm:
- Durability: Body-powered prosthetics are typically more robust and can withstand various environmental conditions.
- Reliability: They are less prone to electronic malfunctions.
- Feedback: Users can often feel the resistance and feedback through the cables, which can provide a better sense of control.
| Feature | Description |
|---|---|
| Power Source | Body muscle activation |
| Mechanism | Cables and pulleys |
| Control | User muscle contractions |
| End Device | Tool or claw for grasping |
| Durability | Generally robust and reliable |
In conclusion, a body-powered prosthetic arm relies on a mechanical design where the user's own muscle movements control the arm via a cable and pulley system. This system allows for basic functionality and grasping.
