Cable-Coupled Robotic Finger Actuation for Force and Dexterity

Solution Overview

Problem

Existing robotic digits face challenges in accommodating a range of forces required for grasping different types of objects due to size constraints on actuators, necessitating improved actuation mechanisms that can provide both large and small forces effectively.

Innovation Solution

A robotic digit design utilizing a main actuator and small actuators coupled by cables, where the main actuator provides gripping force and the small actuators enable dexterous motions, allowing for increased payload capacity and conformability to grasped objects, with mechanisms like capstan drives and idler pulleys facilitating flexible joint movements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the size of actuators integrated into a digit is increased to provide larger gripping forces, then the gripping force capability is improved, but the size constraint of the digit is violated

Engineering Contradiction:

Improvegripping forceVSAvoidactuator size

Core Design Contradiction:

ForceVSVolume of moving object

Solution Approach 1:

The actuation system is divided into two independent actuator types: main actuators for large gripping forces and small actuators for dexterous motions. This segmentation allows each actuator to be optimized for its specific function without being constrained by the need to provide both large force and small size simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Cables serve as intermediaries to transmit force from the actuators to the digit joints. The cable-driven mechanism allows small actuators to generate dexterous motions while main actuators provide gripping forces, with the cables mediating the force transmission across the digit structure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If multiple actuators are integrated into a digit to provide both large and small forces, then the force range capability is improved, but the device complexity increases

Engineering Contradiction:

Improveforce range capabilityVSAvoidactuator integration complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The actuation system is divided into two independent actuator types: main actuators for large gripping forces and small actuators for dexterous motions. This segmentation allows each actuator to be optimized for its specific function without being constrained by the need to provide both large force and small size simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cable-driven mechanism serves multiple functions: it transmits force from main actuators for gripping, transmits force from small actuators for dexterous motions, and provides a compact transmission path that reduces overall system complexity despite multiple actuators.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the digit structure is optimized for dexterous motions using small actuators, then the conformability to objects is improved, but the payload capacity decreases

Engineering Contradiction:

Improveconformability to objectsVSAvoidpayload capacity

Core Design Contradiction:

Adaptability or versatilityVSForce

Solution Approach 1:

The actuation system is divided into two independent actuator types: main actuators for large gripping forces and small actuators for dexterous motions. This segmentation allows each actuator to be optimized for its specific function without being constrained by the need to provide both large force and small size simultaneously.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines the functions of main actuators and small actuators within a unified cable-driven digit structure. The main actuators provide payload capacity while small actuators enable conformability, and both work together through the shared cable transmission system to achieve both objectives simultaneously.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS20250296246A1Cable-coupled robotic finger actuation

Publication Date: 2025.09.25 SANCTUARY COGNITIVE SYST CORP

AI summary

A robotic digit includes a digit base and a joint link coupled to the digit base and movable relative to the digit base about a first axis. An input link is coupled to the joint link through a proximal digit segment and movable relative to the proximal digit segment about a second axis. A cable extending along the proximal digit segment has a distal end coupled to the input link. A cable drive is coupled to a proximal end of the cable and operable to displace the cable relative to the proximal digit segment. A main actuator has an output coupled to move the joint link about the first axis. Relative displacement between the cable and the proximal digit segment via operation of the first cable drive or operation of the main actuator causes movement of the input link about the second axis.