Cooperative Robot Arm Structure for Accurate Payload Sensing
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Solution Overview
Problem
Cooperative robots face challenges in accurately measuring loads due to incorrect payload settings, which can lead to increased stopping distances or unnecessary stopping, and are prone to loadcell damage from non-vertical or rotational loads, making it difficult to measure loads accurately when torques and loads act in various directions.
Innovation Solution
A cooperative robot with an improved arm structure featuring a loadcell, support shaft, and damper, where the loadcell measures loads in a specific direction, and the controller adjusts the payload based on real-time measurements, ensuring accurate load measurement and stability by restricting movement to the load direction and using a damper to prevent excessive movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a payload is set higher than an actual work load, then the cooperative robot can handle heavier loads, but the stopping distance increases
Solution Approach 1:
The patent implements dynamic payload adjustment by equipping the cooperative robot with a load measurement device that continuously monitors the actual load during operation. The controller dynamically adjusts the payload parameter based on real-time measurements, allowing the robot to optimize its collision response characteristics. When the measured load is less than the currently set payload, the controller reduces the payload parameter to match the actual work load, thereby minimizing stopping distance while maintaining safety.
2Length of moving object
If a payload is set lower than an actual work load, then the stopping distance is reduced, but the cooperative robot stops unnecessarily
Solution Approach 1:
The patent employs a feedback mechanism where the load measurement device continuously provides real-time load information to the controller. The controller compares the measured load with the currently set payload parameter and adjusts the payload accordingly. This closed-loop feedback system ensures that the payload parameter always reflects the actual work load, preventing both excessive stopping distances and unnecessary stops due to incorrect payload settings.
3Measurement precision
If a loadcell is used to measure load, then the load can be measured, but the loadcell is prone to damage from non-vertical or rotational loads
Solution Approach 1:
The patent introduces a force measurement device (load measurement device) as an intermediary between the arm and the control system. This device is specifically designed to measure only the vertical force component along the arm's longitudinal axis, effectively filtering out non-vertical loads and rotational torques that would otherwise damage a traditional loadcell. The measurement device converts complex multi-directional forces into a single vertical force measurement, protecting the sensing element from damaging lateral or rotational stresses.
4Adaptability or versatility
If the arm structure allows free movement in multiple directions, then the robot is versatile, but accurate load measurement in a specific direction becomes difficult
Solution Approach 1:
The patent applies local quality by designing the force measurement device to selectively measure only the vertical force component along the arm's longitudinal axis, while being insensitive to forces in other directions. The measurement device is positioned and oriented such that it has high measurement sensitivity in the vertical direction and low sensitivity to lateral or rotational forces. This directional selectivity allows the arm to maintain full movement versatility while achieving accurate load measurement in the specific vertical direction.
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 allows for accurate measurement of loads in the intended direction, even with varied loads and torques, and ensures operation stability by dynamically adjusting the payload, preventing loadcell damage and improving collision response.
Implementation Method 1
a loadcell arranged to be in contact with the other surface of the first plate and one surface of the second plate and measuring a load applied in the first direction to transmit the measured load to the controller
Implementation Method 2
a damper arranged at the other end portion of the support shaft and restricting a movement distance of the support shaft in the first direction
Data Source
AI summary
A cooperative robot according to an embodiment is a cooperative robot including a driver, an arm, and a controller, wherein the arm includes a first plate, a connector arranged on one surface of the first plate and connecting the cooperative robot and the arm to each other, a second plate arranged to be spaced apart from the first plate in a first direction to have one surface facing another surface of the first plate, a loadcell arranged to be in contact with the other surface of the first plate and one surface of the second plate and measuring a load applied in the first direction to transmit the measured load to the controller, at least one support shaft arranged between the first plate and the second plate and extending in the first direction, and a grip gripping an object.