Tendon-Driven Robotic Arm Digits for Dexterous Grasping
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Solution Overview
Problem
Humanoid robots require advanced control mechanisms to achieve precise motion and dexterity for various tasks, especially in interacting with human-made devices, which existing robotic systems struggle to provide due to limited degrees of freedom and torque control.
Innovation Solution
A lower robotic arm assembly featuring a plurality of tendon-driven digits with multiple phalanges and joints, along with a wrist joint assembly and hand, providing 13 degrees of freedom, allowing for complex movements and grasping capabilities through a combination of rotary actuators, tendons, and flexible conduits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional rigid link mechanisms are used, then structural simplicity is maintained, but degrees of freedom and dexterity are limited
Solution Approach 1:
The robotic hand is divided into multiple digits, each with multiple phalanges (first, second, third, and fourth phalanges). Each phalange can rotate independently about an axis, creating multiple degrees of freedom. This segmentation allows the hand to achieve complex grasping motions while maintaining relatively simple individual joint structures.
Solution Approach 2:
The patent employs tendon-driven mechanisms where tendons can be selectively actuated to rotate phalanges about specific axes. This dynamic control system allows the hand to adapt its configuration in real-time for different grasping tasks, transforming a static structure into a dynamically controllable system with multiple degrees of freedom.
2Ease of operation
If multiple joints and phalanges are added to increase dexterity, then grasping capability improves, but torque control becomes more difficult
Solution Approach 1:
Multiple tendons are routed through common conduits that pass through the phalanges. By combining multiple tendon actuation paths into shared conduits, the system reduces the number of separate control channels while maintaining independent torque control capability for each phalange, thus simplifying the overall control architecture.
Solution Approach 2:
Conduits serve as intermediary structures that guide and protect multiple tendons through the phalanges. These conduits act as mediators between the tendon actuation system and the phalangeal joints, enabling precise torque control without requiring direct mechanical connections for each tendon, thereby reducing control complexity.
3Adaptability or versatility
If tendon-driven mechanism is used, then dexterity and motion control improve, but manufacturing precision requirements increase
Solution Approach 1:
The conduit structure serves multiple functions: it guides tendons, provides structural support, and acts as a protective sheath. This multi-functionality reduces the need for separate precision-machined components, thereby lowering manufacturing precision requirements while maintaining the dexterity benefits of the tendon-driven mechanism.
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
Enables precise control and dexterity for humanoid robots, allowing them to perform tasks with multiple degrees of freedom and effectively interact with objects, enhancing their ability to grasp and manipulate items with varied force and motion requirements.
Implementation Method 1
Each tendon is configured to selectively apply a first torque to the respective fourth phalange to urge the fourth phalange to rotate in a first direction about the third axis
Data Source
AI summary
A lower robotic arm includes a base structure, a plurality of digits, and a plurality of tendons. The digits each include first, second, third, and fourth phalanges. Each digit is operatively attached to the base structure at the respective first phalange. A first joint operatively connects the first and second phalange to define a first axis, a second operatively connects the second and third phalange to define a second axis, and a third joint operatively connects the third and fourth phalange to define a third axis, such that the phalanges are selectively rotatable relative to the adjacent phalange, about the respective axis. The tendons are operatively connected to a respective one of the fourth phalanges. Each tendon selectively applies a first torque to the respective fourth phalange to urge the respective phalanges to rotate in a first direction about the respective axes.