Horizontal Articulated Robot Vibration Control via Sensor Extraction
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Solution Overview
Problem
The complexity and cumbersomeness of laying electric wires for angular velocity sensors in horizontal articulated robots, due to the need for multiple sensors and wires, lead to increased durability requirements and cumbersome wire layouts, especially when amplification of vibrations affects the end effector.
Innovation Solution
A horizontal articulated robot configuration where the angular velocity of the first arm is calculated based on the rotational velocities of its motor and the second arm, with the angular velocity sensor on the second arm detecting the combined angular velocities, allowing for subtraction to determine vibration velocity, which is then used to control the first motor, reducing the need for sensors on the first arm and minimizing wire complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If angular velocity sensors are disposed on both the first arm and the second arm for damping control, then the vibration suppression performance is improved, but the number of electric wires increases and the wire layout becomes cumbersome
Solution Approach 1:
The invention extracts the angular velocity sensor from the first arm and relocates it to the second arm. The controller then calculates the angular velocity of the first arm by subtracting the calculated first arm angular velocity (based on motor rotational velocity) from the sensor detection value (which contains both first and second arm angular velocities). This extraction principle reduces the number of sensors and electric wires while maintaining vibration suppression capability.
Solution Approach 2:
The controller acts as an intermediary that processes the sensor data from the second arm and calculates the first arm's angular velocity through mathematical operations. Instead of directly measuring the first arm's angular velocity with a sensor, the controller mediates between the available sensor data and the required control parameter, enabling indirect measurement without additional hardware.
2Manufacturing precision
If angular velocity sensors are disposed on both arms, then precise damping control is achieved, but the durability requirements for electric wires increase due to frequent folding and small curvature
Solution Approach 1:
By extracting the angular velocity sensor from the first arm (which experiences frequent folding and small curvature) and placing it on the second arm, the invention eliminates the durability issue. The second arm's motion characteristics result in less wire folding and larger curvature, improving electric wire reliability while maintaining damping control precision through computational methods.
3Device complexity
If only the first arm's damping control is performed using one angular velocity sensor, then the wire layout is simplified, but the vibration amplification to the end effector is not sufficiently suppressed
Solution Approach 1:
The controller serves as an intermediary that processes the single sensor's data to extract both first and second arm angular velocities. By calculating the difference between the sensor reading and the computed first arm velocity, the system obtains the second arm's velocity, enabling coordinated damping control of both arms and suppressing vibration amplification to the end effector.
Solution Approach 2:
The system implements feedback control by continuously monitoring the angular velocity through the single sensor, calculating the vibration components, and adjusting the motor commands to suppress vibrations in both arms. The feedback loop uses the computed angular velocities to generate corrective control actions that prevent vibration amplification at the end effector.
Data Source
AI summary
A robot includes a first horizontal arm coupled to a base, a second horizontal arm coupled to the base via the first horizontal arm, first and second motors adapted to rotate the respective arms, and first and second encoders adapted to calculate rotational angles and rotational velocities of the respective motors. A first motor control section subtracts first and second angular velocities based on the first and second encoders from a sensor angular velocity detected by an angular sensor, and controls the first motor so that a velocity measurement value obtained by adding a vibration velocity based on a vibration angular velocity as the subtraction result and a first rotational velocity becomes equal to a velocity command value.