Active Tool Holder Control for Jolt-Free Robot Contact Tasks
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Solution Overview
Problem
Existing robot-supported automated systems face challenges in precisely recognizing the moment of contact and controlling contact force, leading to shock-like forces that are undesirable in applications requiring precision, especially when handling sensitive workpieces.
Innovation Solution
A handling apparatus with a mechanical interface, gearless actuators, and a closed-loop control unit that adjusts force from a minimum to a desired level upon contact, using static friction-free actuators and a restoring spring to minimize jerking and maintain precise control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a robot-supported automated system contacts a surface, then the contact task can be performed, but a shock-like contact force occurs which is undesirable in precision applications
Solution Approach 1:
The patent applies beforehand cushioning by introducing a passively flexible element (spring) into the drive train before contact occurs. This spring element absorbs the shock-like contact force that occurs when the robot contacts the surface, preventing direct transmission of impact forces to the robot structure and workpiece, thereby eliminating the harmful shock effect while maintaining contact task capability
Solution Approach 2:
The patent uses a passively flexible element as an intermediary between the robot drive train and the contact interface. This intermediary component (spring) decouples the rigid robot structure from the contact interaction, allowing gradual force buildup and eliminating the direct shock transmission that occurs in rigid systems
2Object-affected harmful factors
If a passively flexible element is inserted in the drive train to reduce shock-like contact force, then the contact force can be reduced, but the passive flexibility acts in an uncontrolled manner and can disturb the desired process
Solution Approach 1:
The patent transforms the static, passive flexibility into a dynamic, controllable system by actively regulating the flexible element during operation. The control system adjusts the flexibility characteristics in real-time based on contact conditions, maintaining process control while preserving the shock-reducing benefits of flexibility
Solution Approach 2:
The patent changes the parameters of the flexible element dynamically during operation. By adjusting the flexibility parameter from fixed to variable, the system can optimize performance for different contact scenarios - maintaining high flexibility during approach to reduce shock, then adjusting to appropriate stiffness during contact to maintain control precision
3Stability of the object's composition
If a rigid system is used, then structural stability is maintained, but even the smallest displacements effected too quickly will result in a high increase in force
Solution Approach 1:
The patent applies beforehand cushioning by placing a flexible element in the drive train before contact occurs. This cushioning element prevents the rigid system from transmitting high force increases during rapid displacements, absorbing energy and limiting force spikes while maintaining overall system stability
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 apparatus enables jolt-free and jerk-free control of contact force, reducing impact energy and overshooting, thus enhancing precision and quality in handling and machining operations.
Implementation Method 1
at least one gearless actuator for positioning the holder in relation to the interface to the manipulator; a restoring spring arranged between the holder and the interface
Implementation Method 2
a restoring spring arranged between the holder and the interface
Implementation Method 3
a sensor unit for directly or indirectly determining the force acting on the at least one actuator
Data Source
AI summary
An apparatus for automated contact tasks and a related method are described. The apparatus includes a mechanical interface for connecting the apparatus to a manipulator, a holder for receiving a tool and being movable in relation to the mechanical interface, at least one actuator for positioning the holder in relation to the mechanical interface, a sensor unit that senses the actuator force provided by the at least one actuator, and a control unit that sets the actuator force to a desired minimum force to press the holder against a stop, while there is no contact between the tool and a surface, and detects contact when the holder moves in relation to the mechanical interface in opposition to the direction of the desired minimum force. The control unit further regulates the actuator force according to a pre-programmed contact force time-characteristic, when contact between the tool and the surface has been detected.