Robot Target Position Detection via Dynamic Loop Gain Control
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Solution Overview
Problem
Existing target position detection techniques for robots are prone to inaccuracies due to operator skill dependence and mechanical fluctuations, leading to potential deformation and particle issues during contact, which affects the reliability of robot teaching processes, especially in complex semiconductor and liquid crystal display device environments.
Innovation Solution
A target position detection apparatus for robots, featuring a control unit that adjusts the control loop gain to reduce the pressing force of the end effector, allowing contact with the target while minimizing deformation and particle occurrence, and utilizing a SCARA-type horizontal articulated arm with a wrist axis to capture positions with higher accuracy by setting the control loop gain lower than a predetermined value, especially in the X-Y and Z axes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the robot operates at high speed to improve productivity, then productivity is improved, but measurement precision deteriorates due to fluctuation factors and time-dependent changing factors becoming dominant
Solution Approach 1:
The patent performs position detection before the robot operates at high speed. By detecting the target position in advance when fluctuation factors are minimal, the system captures accurate position data that can guide subsequent high-speed operations, thus resolving the contradiction between speed and precision
Solution Approach 2:
The patent dynamically adjusts the detection timing based on robot operation phases. Detection is performed when the robot is stationary or moving slowly (before high-speed operation), allowing the system to adapt the measurement process to minimize the impact of speed-related fluctuations on precision
2Measurement precision
If the end effector is contacted with the target to detect position, then position detection is achieved, but deformation of the end effector and target occurs and particles are generated
Solution Approach 1:
The patent applies preliminary anti-action by detecting the target position before the end effector makes contact with it. The robot moves to a position adjacent to the target, detects the position using sensors without contact, and then avoids contact during operation, thereby preventing deformation and particle generation while achieving accurate position detection
Solution Approach 2:
The patent replaces the mechanical contact-based detection method with a non-contact detection method. Instead of using torque and speed changes during contact to detect position, the system uses sensors to detect the target position in advance without mechanical contact, eliminating the harmful effects of deformation and particle occurrence
3Object-affected harmful factors
If the robot is operated at low speed to avoid deformation and particle occurrence, then deformation and particle occurrence are prevented, but measurement precision deteriorates due to dominant fluctuation factors and time-dependent changing factors
Solution Approach 1:
The patent performs position detection as a preliminary action before the robot operates at low speed. By detecting the target position in advance when the robot is positioned adjacent to the target, the system obtains accurate position data without being affected by the fluctuation factors that become dominant during low-speed operation, thus resolving the contradiction between preventing deformation and maintaining measurement precision
Data Source
AI summary
A target position detection apparatus for a robot includes: a robot including an arm configured to be freely moved in at least two directions of X and Y axes, the arm having a wrist axis provided at a distal end of the arm and configured to be freely moved in a horizontal direction, and the wrist axis being provided with an end effector; and a control unit adapted for driving a memory to store a teaching point therein and controlling an operation of the robot such that the end effector will be moved toward the teaching point stored in the memory. The control unit is further adapted for changing a pressing force of the end effector against a target by changing a control loop gain, and bringing the end effector into contact with the target, while setting the control loop gain of the wrist axis lower than a predetermined value at least from a position adjacent to the teaching point at which the target is located, so as to capture a position in a state in which the end effector is in contact with the target, thereby detecting the position of the target.