Force-Feedback Machining Robot for Precise Profile Copying
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Solution Overview
Problem
The accuracy of positioning by a robot is lower than that of a machine tool, limiting its use to processes with moderate machining accuracy and small reaction forces, making it unsuitable for precise cutting operations like profile trimming or pocket machining, which require higher accuracy and larger reaction forces.
Innovation Solution
A machining robot with a cantilever arm and a control system that includes a force sensor to detect reaction forces, allowing for precise control of the tool's movement and adjustment of traveling speeds to manage reaction forces, enabling accurate cutting operations with large reaction forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a robot is used for machining operations, then productivity and automation are improved, but manufacturing precision deteriorates due to lower positioning accuracy compared to machine tools
Solution Approach 1:
A force sensor is introduced as an intermediary between the robot arm and the workpiece. The force sensor detects reaction forces during machining and feeds this information back to the control system, which then adjusts the robot arm's movement in real-time to compensate for positioning errors, enabling precise machining with a robot
Solution Approach 2:
The system implements a closed-loop feedback mechanism where the force sensor continuously monitors reaction forces during machining operations. The control system processes this feedback information and dynamically adjusts the robot arm's positioning and traveling speed to maintain machining precision within ±0.1 mm to ±1.0 mm tolerance
2Device complexity
If a robot with lower rigidity is used instead of a machine tool, then device complexity and cost are reduced, but the ability to handle large reaction forces deteriorates
Solution Approach 1:
The system transitions from static positioning to dynamic adaptation. The robot arm's traveling speed is automatically adjusted based on real-time force sensor feedback. When large reaction forces are detected, the system reduces traveling speed to prevent excessive forces that could affect machining quality or damage the robot arm, enabling the robot to handle varying force conditions
Solution Approach 2:
The control system dynamically changes operational parameters (traveling speed, feed rate) based on detected reaction forces. By adjusting these parameters in real-time, the system optimizes the balance between machining efficiency and the robot arm's force handling capability, enabling precise cutting operations with large reaction forces
3Manufacturing precision
If manual copying operations are performed to achieve precise cutting, then manufacturing precision is maintained, but productivity deteriorates due to skill dependency and slow operation
Solution Approach 1:
The system enables automated self-adjustment during machining operations. The force sensor automatically detects reaction forces and the control system autonomously adjusts traveling speed and positioning without requiring skilled operator intervention. This eliminates skill dependency while maintaining precision and significantly improves productivity through automated operation
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
Enables highly accurate machine cutting operations like profile trimming, profile roughing, and pocket machining with large reaction forces, achieving machining accuracy within ±0.1 mm to ±1.0 mm tolerance, even with a less rigid robot arm, and improves machining efficiency by managing reaction forces.
Implementation Method 1
a force sensor to detect a reaction force from the work
Data Source
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AI summary
A robot control system (3) according to an embodiment is a control system for a robot (2) comprising an arm (4), the arm (4) being capable of holding a tool (T) while rotating the tool (T) and capable of moving the tool (T) in at least two-dimensional directions, the arm (4) being equipped with a rotating mechanism (7) provided for the tool (T). The robot control system (3) comprises a load-acquiring unit (13) and a control-signal-generating unit (14). The load-acquiring unit (13) is configured to acquire a force measured by a force sensor (9) configured to measure a force applied from the tool (T) to the arm (4) during profile copying performed on a machining object (W) by moving the arm (4) while a copying guide attached to the arm (4) and a copying mold placed on the machining object (W) are kept in contact with each other. The control-signal-generating unit (14) is configured to automatically control the arm (4) by generating a control signal for the arm (4) in accordance with the force acquired by the load-acquiring unit (13) and with control information for the arm (4) regarding the profile copying, and by outputting the control signal to the arm (4).