Robot Arm Vibration Suppression via Inertia Sensor Feedback
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Solution Overview
Problem
Existing robots with low-rigidity joint portions suffer from vibration issues due to the use of spring elements, leading to slow response times and reduced control precision, especially when calculating compensation for acceleration detected by sensors at the tip of the arm link, which requires complex coordinate transformations and can result in singular points, impairing vibration suppression.
Innovation Solution
A robot design with inertia sensors installed at each arm link to detect angular velocity and acceleration, allowing for posture-dependent feedback control of drive sources using correction components derived from these measurements, eliminating the need for complex coordinate transformations and singular point calculations, thereby enhancing vibration suppression and response speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If acceleration sensor is installed at the tip portion of the arm link portion to detect vibration, then vibration can be detected, but complex coordinate transformation calculations are required which slow down response speed
Solution Approach 1:
The patent divides the vibration detection function into multiple segments by installing acceleration sensors at each arm link portion rather than only at the tip. This segmentation allows each sensor to detect local vibration independently, eliminating the need for complex coordinate transformations to convert tip acceleration to joint acceleration, thereby improving response speed while maintaining vibration detection capability
Solution Approach 2:
The patent introduces angular velocity sensors as intermediary devices that directly measure the angular velocity of each arm link portion. These sensors act as mediators between the mechanical vibration and the control system, providing direct feedback without requiring complex mathematical transformations, thus resolving the contradiction between measurement precision and response speed
2Reliability
If coordinate transformation calculations are performed to convert tip acceleration to joint acceleration, then vibration suppression can be achieved, but calculation complexity increases and response speed decreases
Solution Approach 1:
The patent extracts the complex coordinate transformation calculations from the control system by directly measuring angular velocity at each joint using angular velocity sensors. This extraction eliminates the need for Jacobi transformation and matrix calculations, reducing control system complexity while maintaining vibration suppression capability through direct feedback
Solution Approach 2:
The patent replaces the mathematical calculation system (coordinate transformation) with a direct mechanical measurement system (angular velocity sensors at each joint). This substitution eliminates the need for complex computations by directly obtaining the required angular velocity information from sensors, thereby reducing calculation complexity and improving response speed
3Measurement precision
If high-speed computing unit is used to improve calculation precision, then accurate acceleration feedback can be achieved, but system complexity and cost increase
Solution Approach 1:
The patent enables each arm link portion to self-measure its own angular velocity using locally installed angular velocity sensors. This self-service approach eliminates the need for a high-speed computing unit to perform complex calculations, as each sensor directly provides accurate feedback about its own joint's motion, thereby improving measurement precision without increasing computing system complexity
4Ease of operation
If same control is performed for all arm postures, then control simplicity is maintained, but vibration suppression effectiveness decreases in certain postures
Solution Approach 1:
The patent implements dynamic control by installing angular velocity sensors at each arm link portion, enabling the control system to adaptively respond to different arm postures. Each sensor provides real-time feedback about the actual angular velocity at its location, allowing the control system to dynamically adjust compensation forces according to the current posture, thereby improving vibration suppression effectiveness while maintaining control simplicity through modular sensor-based feedback
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
The robot effectively suppresses vibration across varying postures without the need for complex calculations, ensuring stable control and increased response speed by using posture-dependent feedback control with inertia sensors, reducing the risk of singular points and improving overall control performance.
Implementation Method 1
a first inertia sensor that is installed at the first arm and detects the angular velocity or acceleration of the first rotation axis of the first arm
Data Source
AI summary
A robot includes respective arms, respective drive sources, respective angle sensors, respective inertia sensors, a posture detection unit that detects the posture of a third arm, and a second drive source control unit that selects, on the basis of a detection result of the posture detection unit, any one of a second (A) correction component, which is derived from an angular velocity ωA3 of a second axis of a third arm obtained from a third inertia sensor, an angular velocity ωA2m of a second axis of a second arm obtained from a second angle sensor, and an angular velocity ωA3m obtained from a third angle sensor, and a second (B) correction component, which is derived from an angular velocity ωA2 obtained from a second inertia sensor and the angular velocity ωA2m, and feeds back the selected correction component to control the second drive source.