Tendon-Routed Lower Arm Assembly for Lightweight Robotic Hands
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Solution Overview
Problem
Current robotic hand technologies struggle to replicate the full range of motion, flexibility, and adaptability of a human hand, particularly in performing delicate grasping and manipulation of objects with varied sizes, shapes, and textures, while also facing challenges in power consumption and durability, which limits their application in human-centric environments.
Innovation Solution
A humanoid robot design featuring a forearm assembly with a tapered frame housing multiple actuators, a tendon-based actuation system, and a sophisticated wrist assembly with a carpal tunnel-like structure, enabling high dexterity and compact design through a distributed actuation system with cycloidal drives and tendon routing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actuators are integrated directly within the hand, then control precision and responsiveness are improved, but device size and mass increase
Solution Approach 1:
The system divides the actuation function into two segments: motors are located in the forearm while tendons transmit force to the hand. This segmentation allows the hand to remain lightweight for dexterity while the forearm houses the motor mass, resolving the contradiction between control precision and hand mass.
Solution Approach 2:
Tendons serve as intermediaries that transmit mechanical force from the forearm actuators to the hand joints. This intermediary mechanism enables precise control of hand movements without requiring heavy motors to be integrated directly into the hand structure.
2Adaptability or versatility
If the number of actuators is increased to achieve full range of motion, then adaptability and versatility are improved, but device complexity increases
Solution Approach 1:
The forearm assembly serves multiple functions: it houses actuators, provides structural support, and contains tendon routing channels. This multi-functionality reduces overall system complexity by consolidating components that would otherwise require separate structures.
Solution Approach 2:
The tendons are routed through channels within the forearm frame structure, nesting the tendon routing system inside the existing structural framework. This nesting approach avoids adding external complexity while achieving full range of motion through multiple actuators.
3Ease of operation
If a compact hand design is implemented, then ease of operation in confined spaces is improved, but the capacity for fine motor skills deteriorates
Solution Approach 1:
The motors are extracted from the hand and placed in the forearm, allowing the hand to be minimized in size for access to confined spaces while retaining fine motor capability through the tendon transmission system that delivers precise force control to each finger joint.
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 design achieves high dexterity and efficient operation with fewer than 20 motors, allowing seamless interaction with diverse objects and maintaining a compact form factor, suitable for complex tasks in industrial, service, and healthcare sectors.
Implementation Method 1
cycloidal drives and tendon routing
Data Source
AI summary
The disclosure presents a humanoid robot with an upper region (head, torso, arms with forearm assemblies, end effectors), lower region (legs), and connecting central region. Each end effector features index, middle, ring, little finger, and thumb assemblies attached to a housing of said end effector. The housing includes interior wall extents creating spaces for tendon routing, where the first distance between first and second wall extents is less than 45% of the second distance between third and fourth wall extents. Tendons controlling finger movements pass between these wall extents. The robot incorporates a wrist assembly connecting the housing of the end effector to the forearm, actuators housed in the forearm that control the tendons, and a carpal tunnel-like structure that guides tendons from forearm to base of the housing, enabling precise hand movements without requiring actuators in the hand itself.