Robot Screwdriving Alignment for Reliable Standard Screw Engagement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for controlling robot manipulators to screw in screws already engaged in threads lack reliability and efficiency, particularly when dealing with standard screws, and often require costly industrial screws.
Innovation Solution
A method involving a robot manipulator with 4 to 7 degrees of freedom that positions and orients a tool with force-regulated and impedance-regulated movements to achieve a positive locking connection with the screw, allowing for controlled screwing and removal with defined torque and rotational adjustments, enabling the use of standard screws.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to control robot manipulators for screwing operations, then the process is simple, but the reliability is poor and standard screws cannot be reliably used
Solution Approach 1:
The screwing operation is divided into distinct phases: approach phase, engagement phase, screwing phase, and removal phase. Each phase has specific control parameters and objectives, allowing the complex task to be managed through structured segmentation while maintaining high reliability
Solution Approach 2:
The control method dynamically adjusts the robot manipulator's movement characteristics throughout the operation. During approach, precise positioning is used; during engagement, force-regulated tilting movements are applied; during screwing, torque control is implemented. This dynamic adaptation enables reliable operation with standard screws
Solution Approach 3:
The system continuously monitors torque, force, and position parameters during each phase and adjusts control commands accordingly. Force-regulated and impedance-regulated movements provide real-time feedback mechanisms that ensure reliable engagement and screwing while accommodating variations in standard screw characteristics
2Reliability
If force-regulated and impedance-regulated movements are used to achieve positive locking connection, then the reliability improves, but the control complexity increases
Solution Approach 1:
The robot manipulator performs preliminary positioning of the tool over the tool engagement interface with high precision before engagement. The tool central axis is pre-oriented with maximum deviation of 8° concentrically with the screw central axis, and the tool is positioned at a defined distance from the interface. This preliminary action ensures reliable connection while reducing the complexity of the actual engagement phase
Solution Approach 2:
The engagement process uses periodic tilting movements of the tool central axis. These closed tilting movements are applied in a controlled sequence to achieve positive locking connection, breaking down the complex engagement task into manageable periodic actions that improve reliability without overwhelming control complexity
3Reliability
If the tool is turned back through a defined angle after reaching torque limit, then the screwing reliability improves, but the operation time increases
Solution Approach 1:
The turning back operation is merged with the removal phase preparation. After the tool is turned back through the defined angle range of [0.01° to 10°] to ensure proper screw engagement and thread formation, the tool is immediately prepared for removal along the tool central axis. This merging of operations ensures reliability while minimizing total operation time
Solution Approach 2:
The control system dynamically changes parameters during the turning back phase, adjusting torque, speed, and position parameters to optimize the process. The defined angle range [0.01° to 10°] is selected based on screw characteristics and engagement requirements, balancing reliability improvement with time efficiency
4Reliability
If closed tilting movements and lateral translatory movements are used for tool removal, then the reliability of successful removal improves, but the control complexity increases
Solution Approach 1:
The removal operation is segmented into vertical movement along the tool central axis and superimposed lateral closed translatory movements. This segmentation allows each movement component to be controlled independently, improving removal reliability while managing control complexity through structured decomposition of the removal task
Data Source
AI summary
The invention relates to a method of controlling a movable robot manipulator for screwing in a screw at least already plugged into a thread, wherein the screw has a screw head with a tool engagement interface, the robot manipulator has at its distal end a tool designed to engage the tool engagement interface, the screw has a screw central axis, and the tool has a tool central axis about which the tool of the robot manipulator is rotatable. The proposed method includes the following steps of: defining a position of the tool engagement interface of the screw at least plugged into the thread, positioning the tool over the tool engagement interface and orienting the tool central axis with a maximum deviation of 8° concentrically with the screw central axis, with force-regulated and/or impedance-regulated closed tilting movement of the tool central axis, moving the tool along the tool central axis into the tool engagement interface until there is a connection between the tool and the tool engagement interface, screwing in the screw in a first direction of rotation of the tool until a defined limit value G1 of a torque/force acting on the tool has been reached or exceeded, once the limit value G1 has been reached or exceeded, turning back the tool counter to the first direction of rotation through a defined angle in the range of [0.01° to 10°], and removing the tool from the tool engagement interface along the tool central axis.