Seamless prosthetic and orthotic control requires a holistic system approach

Why It Matters

For designers of assistive technologies, this means moving beyond purely mechanical or algorithmic solutions. It necessitates a deep dive into human-computer interaction, sensory feedback, and the dynamic nature of human movement to create devices that feel like natural extensions of the user's body.

Key Finding

The review found that controlling active leg prosthetics and braces is as challenging as their mechanical design. The most effective approach involves viewing these devices not as standalone units, but as integrated parts of a system that includes the user and their environment, with safety being a top priority.

Key Findings

• Control strategies for active lower limb prosthetics and orthotics are crucial for restoring human locomotion.
• A holistic framework considering the user, environment, and device is necessary for advanced control.
• Safety mechanisms are paramount for real-world application and regulatory approval.

Research Evidence

Aim: What are the state-of-the-art control strategies for active lower limb prosthetic and orthotic devices, and how can they be effectively interfaced with the user's sensory-motor control system for daily locomotion?

Method: Literature Review

Procedure: The researchers conducted a comprehensive review of existing literature on control strategies for active lower limb prosthetics and orthotics, focusing on their application in daily living activities. They developed a classification scheme for comparing these strategies and proposed a general framework for controlling such devices.

Context: Rehabilitation robotics, assistive devices, human locomotion

Design Principle

Assistive devices should be designed as integrated components within a user-environment-device ecosystem.

How to Apply

When designing any wearable assistive technology, map out the interactions between the user's physical and cognitive states, the device's sensors and actuators, and the typical environments of use. Develop control algorithms that dynamically adapt to these interactions.

Limitations

The review focuses on existing literature and may not capture all emerging or proprietary control techniques. The proposed framework is general and requires specific implementation for different devices.

Student Guide (IB Design Technology)

Simple Explanation: To make artificial legs or braces work well, you can't just think about the machine itself. You need to think about how the person using it wants it to move, what they're doing, and where they are. It's like making a team where the person, the device, and the surroundings all work together smoothly.

Why This Matters: Understanding how users interact with assistive devices is key to creating products that are not only functional but also intuitive and safe, improving the quality of life for individuals with mobility impairments.

Critical Thinking: How might advancements in artificial intelligence and machine learning further enhance the 'ecosystem' approach to prosthetic and orthotic control, moving beyond pre-programmed strategies?

IA-Ready Paragraph: The development of advanced control strategies for active lower extremity prosthetics and orthotics necessitates a holistic systems approach, recognizing the device as an integral part of an ecosystem that includes the user and their environment. As highlighted by Tucker et al. (2015), effective control is achieved not by isolating the device, but by understanding and integrating the physical and informatic interactions between the controller, the user, the environment, and the mechanical device itself. This perspective is crucial for designing assistive technologies that seamlessly restore and enhance human locomotion.

Project Tips

• When designing a prosthetic or orthotic device, consider how the user will provide input (e.g., through muscle signals, balance changes) and how the device will provide feedback.
• Research the typical environments where the device will be used (e.g., stairs, uneven terrain) and how these environments affect user control.

How to Use in IA

• Reference this review when discussing the importance of user-centered control systems in your design project, particularly when justifying your chosen control strategy or user interface.

Examiner Tips

• Demonstrate an understanding of the complex human-machine interface in your design, not just the technical specifications of the device.

Independent Variable: Control strategy parameters, user input signals, environmental conditions

Dependent Variable: Locomotion performance (e.g., gait speed, stability), user perceived effort, device responsiveness

Controlled Variables: User's physical condition, specific prosthetic/orthotic device model, testing environment setup

Strengths

• Provides a comprehensive overview of existing control strategies.
• Proposes a novel, unifying framework for device control.

Critical Questions

• What are the ethical considerations when designing control systems that interpret and act on user intent?
• How can the proposed framework be adapted for different types of assistive devices beyond lower limb prosthetics/orthotics?

Extended Essay Application

• An Extended Essay could explore the development and testing of a novel control algorithm based on the proposed framework, focusing on a specific user group and locomotion task.

Source

Control strategies for active lower extremity prosthetics and orthotics: a review · Journal of NeuroEngineering and Rehabilitation · 2015 · 10.1186/1743-0003-12-1