Base-Actuated Tendon Robot Control for Dexterity and Precision
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Solution Overview
Problem
Existing robotic systems face challenges with high costs, bulkiness, and energy inefficiency due to the integration of heavy actuators near joints, and tendon-driven mechanisms suffer from imprecision caused by variability in tendons, limiting the precision of control for dexterous end effectors.
Innovation Solution
A robotic system design where actuators are positioned distant from joints along the kinematic chain, using tendon-driven joints with a neural network feedback control loop to compensate for imprecision, allowing for precise control and energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If actuators are integrated within the mechanical structure near joints to provide precise control, then control precision is improved, but robot mass increases and dexterity decreases
Solution Approach 1:
The patent extracts actuators from the kinematic chain and positions them externally on the base structure. Tendon-driven mechanisms transmit actuation forces through the kinematic chain to the end effector, separating the heavy actuator mass from the moving components while maintaining control capability through the tendon transmission system.
Solution Approach 2:
The patent introduces tendons as intermediary elements to transmit actuation forces from externally positioned actuators through the kinematic chain. These tendons act as flexible transmission media that convey mechanical forces without requiring heavy integrated actuators at each joint, thereby reducing robot mass while maintaining control precision.
2Measurement precision
If actuators are integrated within the mechanical structure near joints to provide precise control, then control precision is improved, but robot dexterity decreases
Solution Approach 1:
The patent extracts actuators from the kinematic chain and positions them externally on the base structure. Tendon-driven mechanisms transmit actuation forces through the kinematic chain to the end effector, separating the heavy actuator mass from the moving components while maintaining control capability through the tendon transmission system.
Solution Approach 2:
The patent segments the robotic system into distinct functional components: externally positioned actuators on the base, tendon transmission elements, and the kinematic chain with end effector. This segmentation allows the heavy actuation system to be separated from the dexterous manipulator, enabling independent optimization of both control precision and dexterity.
3Ease of operation
If tendon-driven mechanisms are used to separate actuators from joints to decrease link mass, then robot dexterity is improved, but control precision deteriorates due to tendon variability
Solution Approach 1:
The patent implements feedback control using sensors that monitor the position and state of the end effector. This feedback information is used to compensate for imprecision introduced by tendon variability, allowing the system to maintain high control precision despite the use of flexible tendon-driven mechanisms. The closed-loop control continuously adjusts actuator commands based on actual system state.
Solution Approach 2:
The patent employs software-based compensation techniques that dynamically adjust control parameters to account for tendon variability. By monitoring actual system behavior and modifying control signals in real-time, the system compensates for changes in tendon length, elasticity, and other variable parameters, maintaining precise control despite mechanical imperfections.
Data Source
AI summary
A robot is provided having a kinematic chain comprising a plurality of joints and links, including a root joint connected to a robot pedestal, and at least one end effector. A plurality of actuators are fixedly mounted on the robot pedestal. A plurality of tendons is connected to a corresponding plurality of actuation points on the kinematic chain and to actuators in the plurality of actuators, arranged to translate actuator position and force to actuation points for tendon-driven joints on the kinematic chain with losses in precision due to variability of tendons in the plurality of tendons. A controller operates the kinematic chain to perform a task. The controller is configured to generate actuator command data in dependence on the actuator states and image data in a manner that compensates for the losses in precision in the tendon-driven mechanisms.