Wireless Time Synchronization for Robot Tip Vibration Control
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Solution Overview
Problem
Existing methods for synchronizing the time of control devices and wireless sensors in robotic systems are inefficient, leading to incorrect vibration calculation and increased vibration due to random delays and labor-intensive cable connections, especially in scenarios where the robot and control device are apart.
Innovation Solution
A control device with a radio signal exchange unit, data acquisition unit, data calculation unit, delay time calculation unit, and time synchronization unit that receives sensor signals from a wireless sensor, calculates delay times based on correlation between command and detected acceleration data, and synchronizes the sensor and control device times, allowing for effective vibration suppression through learning control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If method (A) of directly connecting the control device and wireless sensor by cable is used for synchronization, then time synchronization reliability is improved, but installation complexity and labor time increase due to robot and control device being arranged apart
Solution Approach 1:
The patent replaces the mechanical cable connection system with a wireless communication system. The control device and sensor exchange time synchronization signals wirelessly, eliminating the need for physical cable connections while maintaining synchronization reliability. This resolves the contradiction by substituting the mechanical connection method with a wireless electromagnetic signal-based method.
2Device complexity
If method (B) of transmitting current time signal wirelessly is used for synchronization, then installation complexity is reduced, but synchronization accuracy deteriorates due to random delay in wireless transmission
Solution Approach 1:
The patent implements a feedback mechanism where the sensor transmits its received time stamp back to the control device. The control device compares the transmitted time stamp with its own current time to calculate the actual transmission delay. This delay information is then used to compensate for timing errors in subsequent measurements, thereby maintaining synchronization accuracy despite wireless transmission delays.
Solution Approach 2:
The patent performs preliminary delay measurement and compensation before actual vibration measurement begins. By conducting time synchronization calibration in advance and storing the measured delay characteristics, the system prepares compensation parameters that will be applied during subsequent measurements, ensuring accuracy without real-time delay affecting the main measurement process.
3Ease of operation
If vibration measurement is performed using wireless sensor detached from robot, then ease of operation is improved for repositioning, but time and labor increase for resetting position and direction every time sensor is detached
Solution Approach 1:
The patent implements automatic position and direction calibration functionality that allows the sensor to self-adjust when reattached to the robot. The sensor automatically detects its new position and orientation relative to the robot coordinate system and performs self-calibration without requiring manual resetting by the operator, thereby maintaining ease of repositioning while eliminating the time loss associated with manual resetting.
4Productivity
If robot operates at high velocity to shorten cycle time, then productivity is improved, but vibration at tip part increases due to insufficient rigidity
Solution Approach 1:
The patent uses feedback from the wireless sensor to detect vibration at the robot tip during high-velocity operation. The control device receives acceleration data from the sensor, processes it to identify vibration components, and generates compensation signals that are fed back to the robot control system. This feedback loop enables active vibration suppression that allows the robot to operate at high velocities without excessive vibration, thereby maintaining both productivity and operational quality.
Data Source
AI summary
A control device controls a mechanical device having a movable member driven by a motor. The control device includes a radio signal exchange unit that receives a sensor signal indicating a position, a velocity or an acceleration of a tip part of the movable member, a data acquisition unit that acquires first time-series data of acceleration based on the received sensor signal, a data calculation unit that calculates second time-series data of acceleration at the tip part based on a drive command to the motor, a delay time calculation unit that calculates, when the mechanical device performs a predetermined basic operation, a delay time of the first time-series data to the second time-series data, based on a degree of correlation between the first and second time-series data, and a time synchronization unit that synchronizes time of the sensor part and control device based on the delay time.