Robot Gripper Calibration Using Contact-Sensed Rack Recesses
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Solution Overview
Problem
Inaccurate calibration of robot grippers in medical testing and processing systems leads to collisions, jams, and unwanted specimen spillage during the transportation of biological liquid containers, as existing methods lack precision in determining the exact positioning of grippers relative to sample racks.
Innovation Solution
A method and apparatus utilizing a robot with a gripper equipped with a crush sensor and a crash sensor, along with a calibration tool, to accurately determine the position of a sample rack by sensing vertical and horizontal contacts, allowing precise calibration of the gripper's position within a coordinate system to prevent collisions and ensure accurate pick and place operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then the calibration process is simple, but positioning precision deteriorates leading to collisions and specimen spillage
Solution Approach 1:
A calibration tool is introduced as an intermediary object between the gripper and the sample rack. This calibration tool features a known geometric structure with a recess that receives the gripper, allowing precise determination of the gripper's position and orientation relative to the sample rack through sensor measurements of the calibration tool's geometry
Solution Approach 2:
Traditional mechanical calibration methods are replaced with a sensor-based measurement system. The crush sensor and crash sensor detect physical contact events, and the controller processes these sensor signals to calculate precise positional and orientational parameters, substituting complex mechanical adjustment procedures with automated sensing and computation
2Reliability
If calibration accuracy is improved, then collisions and spills are reduced, but the calibration process becomes more complex
Solution Approach 1:
The calibration tool serves multiple functions: it provides a reference geometry for position determination, defines the gripper's orientational parameters through its recess structure, and enables both vertical and horizontal calibration through its design features. This multi-functionality reduces the need for multiple separate calibration devices
Solution Approach 2:
The calibration system uses the robot's own sensors (crush sensor and crash sensor) and controller to perform the calibration, rather than requiring external specialized equipment. The robot grasps the calibration tool and uses its existing sensing capabilities to determine its own positional parameters relative to the sample rack
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 enables precise calibration of the gripper's position relative to sample racks, reducing the risk of collisions and spills, and enhancing the accuracy of robotic pick and place operations in medical testing and processing systems.
Implementation Method 1
a crush sensor and a crash sensor, the crush sensor configured to sense a vertical crush event
Implementation Method 2
the crash sensor configured to sense a horizontal crash event
Data Source
AI summary
Methods of calibrating a position of a component include providing a robot with a gripper and crush and crash sensors, a calibration tool coupled to the gripper, and the component, which has a recess and a crush zone. The methods also include moving the gripper in a first direction to sense contact between the calibration tool and the crush zone, recording the contact position, and moving the gripper to insert the tool into the recess. The gripper is then moved in second directions to sense contact between the tool and the recess and moved in third directions to also sense contact between the tool and the recess. The methods further include recording and processing the contact positions to determine a surface location in the first direction and a physical center of the recess. Robot calibration apparatus for performing the method is also disclosed, as are other aspects.