Horizontal Articulated Robot Resonance Avoidance Control
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Solution Overview
Problem
Existing control methods for horizontal articulated robots struggle to effectively suppress resonance, which leads to inaccurate positioning and increased vibration, especially due to the complexity of calculations and the requirement for force sensors, and are not optimally suited for horizontal robots despite being developed for vertical robots.
Innovation Solution
A control method that recreates the operation plan for horizontal articulated robots by setting a resonance avoidance speed range and reducing the maximum speed of axes within this range, particularly focusing on the axis where the base and coupled body are connected, to minimize resonance occurrence with reduced computational effort.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If resonance suppression control is implemented using dynamic characteristic model calculation, then vibration suppression effectiveness is improved, but computational complexity increases
Solution Approach 1:
The patent changes the control parameter from complex dynamic characteristic model calculations to simple speed parameter adjustments. By identifying and avoiding specific speed ranges that trigger resonance, the system achieves vibration suppression through parameter modification rather than complex computation, thus reducing computational complexity while maintaining suppression effectiveness.
Solution Approach 2:
The patent performs preliminary identification of resonance avoidance speed ranges for each axis before actual robot operation. By pre-determining which speed ranges to avoid and incorporating this information into the speed command generation, the system eliminates the need for real-time complex calculations, reducing computational burden while ensuring vibration suppression.
2Measurement precision
If force sensors are attached to detect resonance, then vibration detection accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent utilizes the robot's own encoder data to detect and identify resonance conditions. By analyzing vibration frequencies from existing encoder outputs without adding external force sensors, the system achieves vibration detection using only the robot's built-in components, thereby avoiding increased device complexity and cost.
Solution Approach 2:
The patent replaces the mechanical force sensor-based detection system with an electronic/data-based detection method using encoder signals. By substituting physical sensors with signal processing of existing motor feedback, the system achieves vibration detection accuracy without adding mechanical components, reducing device complexity.
3Adaptability or versatility
If resonance suppression methods designed for vertical articulated robots are applied to horizontal articulated robots, then method applicability is improved, but control optimization is worsened
Solution Approach 1:
The patent recognizes that horizontal and vertical articulated robots have different vibration characteristics and resonance behaviors. By tailoring the resonance avoidance speed ranges specifically for each axis of horizontal articulated robots based on their unique characteristics, the system achieves optimized control rather than applying a generic method, thus improving reliability while maintaining adaptability.
4Reliability
If robot speed is reduced to avoid resonance, then vibration suppression is improved, but productivity decreases
Solution Approach 1:
The patent dynamically adjusts robot speed based on real-time operation conditions and pre-identified resonance avoidance ranges. Rather than uniformly reducing speed, the system only modifies speed commands when approaching resonance-prone ranges, allowing the robot to operate at maximum speed during safe ranges. This dynamic adjustment maintains productivity while achieving vibration suppression when necessary.
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
This approach effectively suppresses resonance in horizontal articulated robots with minimal computational overhead, ensuring accurate positioning and reduced vibration, even in the absence of force sensors, by adjusting motor speeds to avoid natural vibration frequencies.
Implementation Method 1
resonance may occur in the robot accompanying with the operation of the robot. When resonance occurs, the distal end of the robot, i.e., the position of the end effector, also vibrates
Data Source
AI summary
For each axis of a robot, a resonance avoidance speed range is determined in advance based on a natural vibration frequency or the like of the robot. When an operation plan of the robot is created based on an operation command (step 101), a maximum speed of a motor in the operation plan is acquired (step 102), whether or not the maximum speed is included in a resonance avoidance speed range is determined (step 103), and when it is included, the operation plan is recreated such that the maximum speed is equal to or lower than a lower limit speed of the resonance avoidance speed range (step 104).