Jointed Mechanical Device Elastic Actuator Control
Solution Overview
Problem
Jointed mechanical devices, such as robotic prosthetic hands, face challenges in achieving fine motor control due to limited sensory feedback and the impracticality of additional feedback sensor systems, resulting in limited utility and functionality.
Innovation Solution
A jointed mechanical device with a control system that automatically switches between motion control and force control modes, using an actuating structure with elastic and non-elastic elements, and a force actuator, allowing for precise force adjustment without explicit force sensors, enabling more sophisticated grasping and manipulation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional feedback sensors are added to improve fine motor control, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The elastic element serves dual purposes: it acts as both a mechanical component for force transmission and as a sensory element that provides force feedback information to the control system. This self-service approach eliminates the need for separate force sensors, reducing device complexity while maintaining measurement precision for force control
Solution Approach 2:
The actuating structure with elastic elements performs multiple functions simultaneously: it transmits actuator force to move the digit, stores and releases elastic energy for natural motion, and provides force feedback information to the control system. This multi-functionality reduces the need for additional dedicated components
2Adaptability or versatility
If more EMG signals are used to control more components, then adaptability is improved, but the limited number of available EMG signals becomes insufficient
Solution Approach 1:
The control system uses feedback from the elastic elements to automatically adjust actuator force based on contact conditions. This feedback mechanism allows the system to perform sophisticated force control tasks with limited EMG signals, as the elastic element feedback provides real-time information about contact force and object properties
Solution Approach 2:
The elastic elements act as intermediaries between the actuators and the digits, translating limited EMG control signals into sophisticated grasping behaviors. The elastic elements mediate the interaction by providing passive mechanical feedback that enriches the control system's understanding of contact conditions without requiring additional EMG signals
3Device complexity
If force control is implemented without force sensors, then device complexity is reduced, but measurement precision of force may be compromised
Solution Approach 1:
The elastic element serves dual purposes: it acts as both a mechanical component for force transmission and as a sensory element that provides force feedback information to the control system. This self-service approach eliminates the need for separate force sensors, reducing device complexity while maintaining measurement precision for force control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables fine motor control and prevents damage to objects by adjusting force application upon contact, utilizing limited EMG signals effectively, thereby enhancing the functionality of jointed mechanical devices like prosthetic hands.
Implementation Method 1
The actuating structure (206) may include at least one elastic component (214)
Data Source
AI summary
A jointed mechanical device is provided. The device includes at least one element having a fixed end and a deflectable end. The device also includes at least one actuating structure having a first end coupled to at least the deflectable end of the element, where the actuating structure includes at least one elastic element in series with at least one non-elastic element. The device further includes at least one force actuator configured to apply an actuator force to a second end of the actuating structure. Additionally, the device includes a control system for adjusting an operation of the force actuator based at least one actuation input, an amount of the actuator force, and an amount of displacement generated by the force actuator.