Robot Link Geometry and Torque Sensing for Pinch Prevention
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Solution Overview
Problem
Existing robot joint structures fail to effectively prevent objects, such as hands or arms, from being pinched between rotating link members, leading to potential injury and operational inefficiencies due to inadequate detection and prevention mechanisms.
Innovation Solution
A robot design featuring link members with a shape that gradually increases in width from the center towards the ends, combined with a sensor system that detects torque around the axial line, allowing for early detection and prevention of pinching by controlling the robot's operations when a predetermined torque threshold is exceeded.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional link member shapes are used, then the robot structure is simple, but objects can be pinched between link members causing injury and operational inefficiencies
Solution Approach 1:
The link members are designed with curved boundary surfaces instead of straight edges. Specifically, the boundary surfaces have a pinching prevention shape where the distance from the axial line to the boundary surface increases continuously from the root toward the distal end, creating a tapered curved profile that prevents objects from being pinched between rotating link members
Solution Approach 2:
The patent applies preliminary anti-action by pre-configuring the link member geometry to prevent pinching before it can occur. The curved boundary surfaces are designed in advance to eliminate pinch points, and torque sensors are pre-installed to detect potential pinching forces before they cause injury, allowing the control device to preemptively stop operation when threshold values are approached
2Reliability
If link members have straight boundary surfaces, then manufacturing is easier, but pinching prevention is ineffective
Solution Approach 1:
The boundary surfaces of the link members are designed with continuous curves rather than straight lines. The curved profile allows objects to roll off or be guided away from the rotation path, effectively preventing pinching. While this increases manufacturing complexity compared to straight edges, modern CNC machining and molding techniques can efficiently produce these curved profiles
3Reliability
If no torque detection is implemented, then the device is simpler, but pinching cannot be detected early enough to prevent injury
Solution Approach 1:
The patent implements feedback by installing torque sensors on the rotary actuators that drive the link members. These sensors continuously monitor the torque during operation and provide real-time feedback to the control device. When the detected torque exceeds a predetermined threshold value indicating potential pinching, the control device immediately stops the robot operation, preventing injury
Solution Approach 2:
The torque sensors are configured to detect pinching forces before they reach dangerous levels. By setting threshold values that are lower than the force required to cause injury, the system takes preliminary action to stop operation in advance, preventing pinching before it can cause harm
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 design significantly reduces the probability of pinching by allowing for early detection and prevention of excessive pressurization forces, enhancing safety and operational reliability by ensuring objects are not pinched between link members.
Implementation Method 1
a sensor that detects a force around the axial line acting between the link members due to an object pinched between the link members
Data Source
AI summary
A robot including: two link members with longitudinal axes that are coupled such that the link members are able to relatively rotate about an axial line; and a sensor that detects a force around the axial line acting between the link members due to an object pinched between the link members, in which the robot has such a shape that a width dimension in a direction along a plane of a cross-sectional surface of at least one of the link members, which perpendicularly intersects the axial line, on at least one sides from the longitudinal axes that intersect the axial line continuously spread from at least midway positions of the at least one of the link members in the direction of the longitudinal axes toward the axial line, respectively.