EV Charger Connector Compliance Assembly for Low-Force Docking
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Solution Overview
Problem
Existing systems for automatically inserting or extracting electric vehicle charging connectors face challenges due to misalignment, which require excessive force and pose risks of damage to the vehicle, charging robot, or injury to persons, and are often complex and costly.
Innovation Solution
A device combining an actuated positioning mechanism with compliance assemblies to apply alternating moments and forces in directions different from the insertion/extraction direction, facilitating a quasi-static motion to reduce friction and misalignment during connector insertion and extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a tightly fitting connector-socket geometry is used, then connection reliability is improved, but insertion and extraction forces increase due to friction
Solution Approach 1:
A vibration unit is integrated into the manipulator to excite the charging connector with vibrations during insertion and extraction. This mechanical vibration reduces the friction between the tightly fitting connector and socket, enabling reliable connection while reducing the forces required. The vibration unit includes an actuator and a vibration transmission mechanism that directly couples the connector during the connection process.
Solution Approach 2:
A vibration unit acts as an intermediary between the manipulator and the connector. This intermediary component transmits vibrational energy to the connector, facilitating easier insertion and extraction without compromising the tight fit between connector and socket. The vibration unit mediates the interaction by adding a dynamic element that reduces friction during the connection process.
2Reliability
If misalignment between connector and socket is compensated, then connection reliability is improved, but system complexity increases
Solution Approach 1:
Sensors detect misalignment between the connector and socket in real-time, and this feedback information is used by the control unit to adjust the manipulator's position and orientation. The feedback loop continuously monitors the alignment status and dynamically corrects deviations, ensuring reliable connection without requiring overly complex mechanical alignment mechanisms.
Solution Approach 2:
The system transitions from static alignment compensation to dynamic adjustment. The manipulator can dynamically adjust its position and orientation during the connection process based on real-time sensor feedback. This dynamic capability allows the system to handle misalignment adaptively, reducing the need for complex pre-alignment mechanisms while maintaining high connection reliability.
3Force
If vibration is applied to reduce insertion force, then friction is reduced, but design requirements and cost increase
Solution Approach 1:
The vibration unit is designed to serve multiple functions: it reduces friction during both insertion and extraction, and it can be integrated into existing manipulator structures. By making the vibration system multi-functional and compatible with standard manipulator components, the design requirements are minimized while achieving the force reduction benefit.
Solution Approach 2:
The vibration unit is designed to be self-contained and self-regulating, requiring minimal additional control infrastructure. The system automatically applies vibrations during the connection process without requiring complex external control systems, thereby reducing overall design requirements while maintaining effective friction reduction.
4Reliability
If compliance stroke is increased to accommodate vehicle motion, then connection reliability is improved, but extraction difficulty increases due to clamping
Solution Approach 1:
Vibrations are applied to the connector during extraction to reduce the clamping force that develops due to compliance stroke and misalignment. The mechanical vibration breaks the friction bond between the connector and socket, enabling easy extraction even when significant compliance stroke has occurred. This allows the system to maintain high connection reliability during charging while facilitating simple extraction when needed.
Data Source
AI summary
A device for connecting an EV charger connector to or disconnecting it from an EV socket with a supposed position and orientation. A connector handling mechanism comprises an actuated positioning mechanism, for moving the connector with at least 2 degrees of freedom with respect to a fixed world of at least one compliance assembly, compliantly moving the connector in at least two degrees of freedom with respect to the fixed world, wherein the at least one compliance assembly is connected kinematically in series with the positioning mechanism, between the fixed world and the connector; and has a compliance stroke defined as the effective displacement between an actual connector position and orientation, and a current/momentary virtual position and orientation of the connector. A first moment and/or force is applied to the connector in a movement direction. A second moment and/or force is superimposed on the first moment and/or force.