Robot Control Device Vibration Suppression via Gravity Center Adjustment
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Solution Overview
Problem
Existing robot control systems face challenges in effectively suppressing vibrations at the tip end of robotic arms due to the difficulty in ensuring space for acceleration speed sensors and wiring near the vibration source.
Innovation Solution
A control device for robots that calculates correction instruction values based on the mass, spring constant, and accelerating speed to adjust the position of the gravity center, allowing for vibration suppression without the need for an acceleration sensor at the vibration source, by using a driving unit, moving unit, and a vertically slidable shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an acceleration speed sensor is assembled at the tip end of the robotic arm to sense vibration, then vibration suppression precision is improved, but device complexity and installation difficulty increase due to space constraints and wiring requirements
Solution Approach 1:
The patent extracts the vibration sensing function from the physical acceleration speed sensor and relocates it to the control device. Instead of measuring vibration at the tip end with a sensor, the system calculates equivalent acceleration values at the control device using motor current detection and dynamic models, thereby eliminating the need for complex sensor assembly at the robotic arm tip.
Solution Approach 2:
The patent introduces motor current detection as an intermediary to infer vibration characteristics. By detecting the current of the motor driving the robotic arm and using dynamic models to calculate equivalent acceleration values, the system obtains vibration information without directly installing sensors at the vibration source, thus reducing device complexity while maintaining measurement effectiveness.
2Reliability
If an acceleration speed sensor is installed near the tip end to achieve accurate vibration measurement, then vibration suppression effectiveness is improved, but ease of manufacture deteriorates due to difficult space assurance and wiring layout
Solution Approach 1:
The patent removes the physical acceleration speed sensor from the robotic arm tip and relocates the sensing function to the control device. The control device calculates equivalent acceleration values using motor current data and dynamic models, eliminating the need for complex sensor installation and wiring at the robotic arm tip while maintaining vibration suppression effectiveness.
Solution Approach 2:
The patent replaces the mechanical sensor-based measurement system with an electrical field-based detection system. By using motor current detection and computational models to infer vibration characteristics, the system eliminates the need for physical sensors at the robotic arm tip, thereby simplifying manufacturing and installation processes while maintaining measurement accuracy.
3Measurement precision
If the gravity center position is adjusted dynamically to suppress vibration, then vibration suppression precision is improved, but device complexity increases due to additional calculation requirements
Solution Approach 1:
The patent performs preliminary calculation of the gravity center position based on the robotic arm's link parameters and joint angles before vibration occurs. By pre-calculating the gravity center position using dynamic models and motor current data, the system prepares correction values in advance, reducing the computational burden during real-time vibration suppression while maintaining positioning precision.
Solution Approach 2:
The patent implements a feedback mechanism where the control device continuously monitors motor current, calculates equivalent acceleration values, determines gravity center position deviations, and adjusts control commands accordingly. This closed-loop feedback system dynamically compensates for vibration by adjusting the gravity center position based on real-time operational conditions, achieving high precision vibration suppression through iterative correction.
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 solution effectively suppresses vibrations at the robot's tip end by adjusting the gravity center's position to match the target position, ensuring smooth operation and ease of implementation without requiring additional sensors at the vibration site.
Implementation Method 1
the support portion 22a functions as a spring element having a spring constant K relative to a force in direction twisting the third shaft 23. Thus, when the tip end portion of the second shaft 22 is accelerated or decelerated, the tip end of the third shaft 23 vibrates relative to the support portion 22a as a center according to an inertial force applied to the third shaft 23 and the subject W.
Implementation Method 2
When the moving unit is accelerated or decelerated, the inertial force that is as same as an inertial force of when the mass of the total load exists is applied to a position of the gravity center distance defined from the support portion of the moving unit supporting the predetermined shaft to the gravity center of the total load of the predetermined shaft and the subject.
Data Source
AI summary
A control device controlling a robot including a driving unit, a moving unit that is slidable along a predetermined track and a predetermined shaft that is slidably supported by the moving unit includes an instruction value calculating unit calculating an instruction value that drives the driving unit such that the moving unit is moved to a target position, an accelerating-speed calculating unit calculating an angular accelerating speed of when the instruction value changes, a gravity-center distance calculating unit calculating a gravity center distance, a correction instruction-value calculating unit calculating a correction instruction value by correcting the instruction value such that a position of the gravity center which is projected on the predetermined track approaches the target position, and a driving control unit controlling the driving unit based on the correction instruction value.