Telescopic Chain Actuation for Lightweight Articulated Reach
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Solution Overview
Problem
Traditional actuation systems for telescopic structures in robots are complex, heavy, and expensive, limiting their ability to sense interaction forces and access cluttered environments, making them unsuitable for assistive robotic applications.
Innovation Solution
A compact and efficient actuation system using a drive chain with interconnected links that conveys cables within a telescopic structure, allowing for horizontal extension and retraction, and vertical translation, with a self-spooling chain cartridge and differential drive transmission, enabling precise control and reduced component costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If traditional actuation systems with revolute actuated joints are used, then articulated reach is provided, but the system becomes large, heavy, and expensive with compounding weight at proximal joints
Solution Approach 1:
The actuation system is divided into multiple independent chain cartridges, each responsible for a specific degree of freedom. Each cartridge contains its own drive chain and actuator, allowing modular weight distribution rather than compounding weight at proximal joints. This segmentation enables the robot to achieve articulated reach while keeping each actuator compact and lightweight.
Solution Approach 2:
The patent replaces traditional revolute joint mechanics with a chain-driven parallel mechanism. Instead of using heavy rotary actuators at each joint, the system uses chain cartridges that pull on cables to achieve motion. This substitution dramatically reduces the weight and size of the actuation system while maintaining the ability to provide articulated reach through coordinated cable tensioning.
2Ease of operation
If traditional actuation systems are used, then articulated motion is achieved, but the design becomes complex and expensive
Solution Approach 1:
The chain cartridge is designed as a universal module that can be replicated for each degree of freedom. Each cartridge performs multiple functions: it provides actuation through the drive chain, guides the chain through guide tracks, and houses the actuator. This multi-functionality in a single modular unit reduces overall system complexity compared to traditional systems that require separate mechanisms for each function.
Solution Approach 2:
The drive chain is nested within the chain cartridge, with the chain looping through guide tracks that are integrated into the cartridge structure. The cables are nested within the chain links, allowing compact packaging of multiple functional elements. This nesting reduces the spatial footprint and simplifies the overall design by eliminating the need for separate housings and mounting structures.
3Weight of moving object
If telescopic structure extends horizontally, then gravity support is self-sufficient, but precise actuation control is needed
Solution Approach 1:
The system incorporates sensors that provide feedback on the position and force experienced by the telescopic structure. This feedback is used by control algorithms to precisely regulate the tension in the drive chains, enabling accurate control of actuation forces. The feedback loop compensates for variations in cable elasticity, chain slack, and friction, maintaining precision despite the simplified horizontal support structure.
Solution Approach 2:
The control system dynamically adjusts parameters such as chain tension, actuator speed, and gear ratio to optimize actuation precision. By changing these parameters in real-time based on task requirements and environmental conditions, the system achieves precise force control while maintaining the benefits of lightweight horizontal telescopic extension.
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 actuation system provides robust and accurate articulation with reduced weight and cost, enabling safer and more effective interaction in diverse environments, enhancing user experience and task completion in assistive robotics.
Implementation Method 1
The drive chain can include a first plurality of inter-connected links conveying at least one first cable within a first interior space of each of the first plurality of inter-connected links
Implementation Method 2
The drive mechanism can impart a linear translation force on the first plurality of interconnected links to cause the distal segment to extend from or retract into the first end of the telescopic structure
Implementation Method 3
In another embodiment, the first chain cartridge can be a self-spooling chain cartridge including a passively rotating pinion coupled to a second end of the drive chain
Data Source
AI summary
Actuation systems and methods for actuating a telescopic structure are provided. The actuation system can include a chain cartridge including a drive chain engageably coupled to a drive mechanism actuated by an actuator coupled to a power supply. The drive chain can include a plurality of inter-connected links conveying at least one cable within an interior space of each inter-connected link. The system can also include a telescopic structure including a plurality of segments configured to extend and retract telescopically and conveying the drive chain therein. The drive chain can couple to a distal segment of the plurality of segments. The drive mechanism can impart a linear translation force on the plurality of inter-connected links to cause the distal segment to extend or retract from the telescopic structure. Methods of actuating the actuation system described herein are also provided.