Optical Speckle 3D Positioning for Robotic Arm Repeatability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for measuring repeated positioning precision of robotic arms, such as using laser trackers, suffer from poor precision, slow tracking speed, and high costs, with indirect measurement methods affecting accuracy and requiring re-establishment of measurement devices for different positions.
Innovation Solution
A device and method utilizing an optical speckle three-dimensional displacement sensor with two image invariant optical speckle capturing devices and a two-dimensional laser interferometer calibration platform, allowing for absolute positioning precision of less than 0.1 μm and fast positioning speed, with a cost-effective calibration module, capable of infinite position and orientation calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a laser tracker is used to measure repeated positioning precision of a robotic arm, then the measurement can be performed over long distances, but the positioning precision deteriorates (25 μm at 5 m, 80 μm at 80 m)
Solution Approach 1:
The patent replaces the mechanical laser tracker system with an optical speckle three-dimensional displacement sensor system. This optical system uses laser speckle patterns and interferometry to achieve high-precision measurement (less than 0.1 μm) without the distance-dependent precision degradation of traditional laser trackers, effectively substituting a mechanical measurement system with an optical one that overcomes the distance-precision tradeoff.
Solution Approach 2:
The patent changes the measurement parameters from direct laser distance measurement to optical speckle pattern analysis. By capturing and analyzing speckle patterns at different positions and using interferometric techniques, the system transforms the measurement approach to achieve sub-micrometer precision independent of measurement distance, fundamentally altering how position is measured.
2Length of stationary object
If a laser tracker is used for measurement, then the measurement range is extended, but the tracking positioning speed becomes slow, limiting robotic arm movement speed
Solution Approach 1:
The patent replaces the slow mechanical scanning system of laser trackers with a high-speed optical capture system. The optical speckle three-dimensional displacement sensor uses rapid camera capture and digital signal processing to achieve fast positioning speed that matches robotic arm movement, eliminating the bottleneck created by mechanical tracker speed limitations.
Solution Approach 2:
The system uses periodic laser beam scanning combined with high-speed optical capture to measure multiple positions efficiently. By implementing periodic measurement cycles that capture speckle patterns at successive positions, the system achieves both comprehensive measurement coverage and high speed, allowing continuous tracking of robotic arm movement without slowing down the robot.
3Manufacturing precision
If conventional three-dimensional laser displacement sensors or contact probes are used, then measurement can be performed within a predetermined range, but measurement points in different directions are not the same point, requiring indirect measurement and calculation which affects positioning precision
Solution Approach 1:
The patent implements a universal measurement system where the optical speckle three-dimensional displacement sensor can measure all three spatial dimensions (X, Y, Z) simultaneously at the exact same physical point. The sensor integrates multiple measurement functions into one device, eliminating the need for separate sensors for different directions and enabling direct measurement of true three-dimensional position without indirect calculation.
Solution Approach 2:
The patent introduces an optical speckle pattern as an intermediary that enables direct measurement of three-dimensional position. The speckle pattern acts as a mediator between the laser beams and the measurement system, allowing all spatial coordinates to be determined from the pattern analysis at a single point, thereby eliminating the need for indirect measurement methods used with conventional sensors.
4Adaptability or versatility
If measurement devices perpendicular to one another are used for three-axis measurement, then measurement can be performed in three directions, but the devices have to be re-established for different positions, resulting in complications
Solution Approach 1:
The patent implements a universal measurement system where the optical speckle three-dimensional displacement sensor can measure all three spatial dimensions (X, Y, Z) simultaneously at the exact same physical point. The sensor integrates multiple measurement functions into one device, eliminating the need for separate sensors for different directions and enabling direct measurement of true three-dimensional position without indirect calculation.
Solution Approach 2:
The patent merges three separate measurement functions (X-axis, Y-axis, and Z-axis measurement) into a single optical speckle displacement sensor. By combining what would traditionally require three perpendicular sensors into one integrated device, the system eliminates the complexity of re-establishing measurement devices for different positions while maintaining full three-dimensional measurement capability.
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 provides precise, fast, and cost-effective measurement of repeated positioning precision for robotic arms, enabling accurate calibration across multiple positions and orientations, enhancing the practicability and performance of robotic systems.
Implementation Method 1
an optical speckle three-dimensional displacement sensor, having two image invariant optical speckle capturing devices perpendicular to each other and a laser displacement sensor
Implementation Method 2
the optical speckle three-dimensional displacement sensor configured to emit three laser beams striking on a same position of the optical speckle image three-dimensional positioning base
Implementation Method 3
a two-dimensional laser interferometer calibration platform, having an optical speckle image three-dimensional positioning base and the optical speckle three-dimensional displacement sensor
Implementation Method 4
the tracker then calculates a distance using a time difference between the emission and reception (ADM mode), or measures a distance between the laser head and the retro-reflecting mirror by using interference of laser light (IFM mode)
Data Source
AI summary
A device for measuring repeated positioning precision of a robotic arm is introduced. Using an optical speckle three-dimensional displacement sensor developed by the inventor, and with collaboration of an optical speckle image three-dimensional positioning base built with an optical speckle coordinate database and having low thermal expansion, an optical speckle three-dimensional absolute positioning space is established. The optical speckle three-dimensional displacement sensor is installed on an end effector of a robotic arm, the robotic arm is moved to have the optical speckle three-dimensional displacement sensor enter an optical speckle three-dimensional absolute positioning space, an optical speckle image of a positioning point is captured and compared with a coordinate optical speckle image in the optical speckle coordinate database, and current three-dimensional absolute positioning coordinates of the end effector of the robotic arm can be obtained.