Collaborative Robot Force Sensor Warm-Up for Stable Collision Detection
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Solution Overview
Problem
Collaborative robots face accuracy issues in collision detection due to temperature drift in force sensors, which occurs when the robot is powered on and the temperature of the force sensor rises, leading to lower detection accuracy.
Innovation Solution
A robot system with a force sensor and a first temperature sensor to detect the force sensor's temperature, along with a control unit that performs a warm-up operation until the temperature reaches a target value, stabilizing the output and reducing temperature drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the robot is powered on and the force sensor operates continuously, then the robot can perform collision detection, but the temperature of the force sensor rises causing temperature drift and reducing detection accuracy
Solution Approach 1:
The patent applies preliminary action by performing a warm-up operation before the robot starts its normal work. During this warm-up period, the robot executes predetermined motions to generate heat in the force sensor, raising its temperature to a stable operating range before actual collision detection begins. This preliminary heating prevents temperature drift during subsequent operations.
Solution Approach 2:
The patent changes the temperature parameter of the force sensor through controlled warm-up operations. By adjusting the duration and intensity of preliminary robot motions, the system raises the force sensor temperature from ambient conditions to a stable operating temperature range, thereby changing the thermal state to eliminate temperature drift effects.
2Measurement precision
If a warm-up operation is performed to stabilize the force sensor temperature, then temperature drift is reduced and detection accuracy improves, but the time required before the robot can operate increases
Solution Approach 1:
The patent applies partial action by performing only the necessary minimum warm-up operations required to bring the force sensor to its operational temperature range. Rather than excessive heating, the system executes predetermined motions for just enough duration to achieve stable temperature, thereby minimizing the time loss while ensuring adequate warm-up.
Solution Approach 2:
The robot performs self-warm-up by executing its own predetermined motions during the warm-up operation. The robot's drive units generate heat through their own operation, which is transferred to the force sensor, eliminating the need for external heating devices and reducing system complexity and time requirements.
3Productivity
If the robot operates immediately after power on, then productivity is maintained, but false collision detection may occur due to temperature drift
Solution Approach 1:
The system performs preliminary warm-up operations before normal productivity-driven work begins. This preliminary phase, though taking some time, prevents false collision detections during productive operations, thereby ensuring that subsequent productivity gains are not undermined by operational errors or unnecessary stoppages.
Solution Approach 2:
The control unit monitors the force sensor output during and after warm-up operations to detect when temperature drift has been minimized. This feedback mechanism allows the system to determine when the force sensor has reached a stable state, enabling the transition from warm-up to productive operation at the optimal moment, balancing reliability and productivity.
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 warm-up operation ensures reliable force detection, reducing the probability of false collision detection and unnecessary deceleration or stoppage of the robot, thereby improving the accuracy and efficiency of the robot's actions.
Implementation Method 1
the force sensor converts the external force into an electrical signal and outputs a change of the external force as a change of the electrical signal
Implementation Method 2
a first temperature sensor detecting a temperature of the force sensor
Implementation Method 3
it is generally known that a phenomenon called temperature drift that the output value changes due to a temperature change occurs
Data Source
AI summary
A robot system includes a robot collaboratively acting with a human, a force sensor provided in the robot and detecting a force, a control unit decelerating or stopping an action of the robot based on output from the force sensor, a first temperature sensor detecting a temperature of the force sensor, and an execution unit performing warm-up operation in the robot until output from the first temperature sensor reaches a first target value.