Elastic Actuator Control for Sensor Failure Compensation
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Solution Overview
Problem
Conventional robots designed for industrial use are not suitable for domestic environments due to their rigidity and lack of flexibility, and they often fail to continue operation safely when sensor failures occur without pre-prepared alternative data or signals.
Innovation Solution
A control apparatus and method for an elastic actuator drive mechanism that includes a desired value output unit, output error compensation unit, internal state decision unit, internal state error compensation unit, and abnormality determination unit, allowing continuous operation even when output measurement units fail, without the need for pre-prepared instructed data or alternative sensor signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional industrial robots use electric motors with high-gain feedback control, then hand position accuracy is improved to 0.1 mm repetition accuracy, but the mechanism becomes rigid and unsafe for domestic environments
Solution Approach 1:
The patent replaces the conventional electric motor-driven mechanical system with an elastic actuator system that uses pneumatic or hydraulic pressure to generate motion. This substitution fundamentally changes the actuation mechanism from rigid motor-driven motion to flexible pressure-driven elastic deformation, achieving both high positioning accuracy and inherent safety through the compliant nature of elastic materials
Solution Approach 2:
The patent changes the physical state and parameters of the actuator system by using elastic materials with specific viscoelastic properties. By controlling pressure parameters and exploiting the time-dependent mechanical behavior of elastic materials, the system achieves precise position control while maintaining safety through controlled compliance and energy dissipation
2Object-affected harmful factors
If conventional robots instantaneously stop operation when sensor failure occurs, then safety is improved, but the robot cannot continue operation and pre-prepared alternative data must be stored in advance
Solution Approach 1:
The patent implements a feedback control system that continuously monitors actuator state and sensor performance. When sensor failure is detected, the feedback mechanism enables the controller to switch to alternative control strategies using remaining functional sensors and actuators, allowing continuous operation without instantaneous shutdown while maintaining safety through ongoing monitoring and adaptive control
Solution Approach 2:
The patent prepares for sensor failure by incorporating redundant sensing capabilities and alternative control pathways in advance. Rather than storing pre-prepared alternative data for every possible failure mode, the system is designed with inherent fault tolerance through multiple sensors and actuators that can compensate for individual failures, cushioning against the impact of sensor failure on operation continuity
3Object-affected harmful factors
If elastic actuators are used to provide flexibility and safety, then the robot is safe and lightweight, but control precision and position accuracy become more difficult to maintain
Solution Approach 1:
The patent exploits the viscoelastic properties of elastic materials, which exhibit time-dependent mechanical behavior. By controlling pressure parameters dynamically and accounting for the time-dependent deformation characteristics of elastic materials through mathematical models, the system achieves precise position control despite the inherent compliance of elastic actuators
Solution Approach 2:
The patent implements sophisticated feedback control that continuously measures actuator deformation and position using multiple sensors. The feedback signal is used to dynamically adjust control parameters and compensate for elastic deformation, maintaining high position accuracy through real-time correction while preserving the safety benefits of elastic materials
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 safe and continuous operation of robots in domestic environments by compensating for output and internal state errors, ensuring the robot can function even when sensor failures occur, without the need for pre-prepared data or alternative signals.
Implementation Method 1
the tubular elastic body attempts to expand mainly in a radius direction. However, by a function of the constraining means, a motion to expand in the radius direction is converted into a motion in a central axial direction of the tubular elastic body
Implementation Method 2
When an internal pressure is given through a fluid injection/ejection means to an inner space of the tubular elastic body by a compressive fluid such as air
Data Source
AI summary
An abnormality determination unit that determines whether or not an output measurement unit is abnormal is provided, and whether or not the output measurement unit is abnormal is determined. When the output measurement unit is abnormal, an elastic actuator is controlled based on a desired internal state decision unit and an internal state error compensation unit. Accordingly, it becomes possible to control the elastic actuator to continuously operate to a predetermined position without instantaneously stopping even when the output measurement unit is abnormal.