Clutched Robotic Joint Module With Quasi-Passive Elastic Torque Assist
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Solution Overview
Problem
Robotic systems face challenges in minimizing power consumption while maintaining adequate force output, often requiring a trade-off between power and efficiency, with existing solutions either sacrificing efficiency for high force output or vice versa, limiting their practicality and autonomy.
Innovation Solution
The development of a clutched joint module incorporating a quasi-passive elastic actuator that combines primary torque from an electric motor with augmented torque from a torsional coil spring, utilizing a clutch mechanism to switch between engaged and disengaged states to optimize energy storage and release, thereby reducing power consumption and enhancing force output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If high-output power systems are employed to meet force output demands, then force output capability is improved, but power consumption increases and efficiency deteriorates
Solution Approach 1:
The system dynamically switches between two operational modes using a clutch mechanism: an elastic mode where the spring stores and releases energy for force assistance, and an inelastic mode where the spring is disengaged. This dynamic switching allows the system to provide high force output when needed while minimizing power consumption during periods when elastic energy storage and release can satisfy the force requirements, thereby resolving the contradiction between force output capability and power consumption.
Solution Approach 2:
The elastic actuator operates through periodic cycles of energy storage and release. The spring is periodically engaged to store elastic energy during phases when less force is required, and then disengaged to release this stored energy when force assistance is needed. This periodic action pattern allows the system to maintain force output capability while reducing average power consumption compared to continuous high-power operation.
2Use of energy by moving object
If efficient power systems are employed to improve efficiency, then power consumption is reduced, but force output capability deteriorates
Solution Approach 1:
The elastic spring acts as an intermediary energy storage device between the power source and the load. Instead of relying solely on the motor to provide continuous high force output, the spring intermediates by storing energy when the motor operates at lower power levels and then releasing this energy to augment the motor's force output when needed. This intermediary mechanism allows efficient low-power operation while maintaining the capability for high force output when required.
3Extent of automation
If portable power sources are used to enable autonomy, then operational independence is improved, but power capacity and duration are limited
Solution Approach 1:
The elastic spring functions as a mechanical energy recovery and storage device. During phases when the robotic system does not require maximum force output, the spring stores elastic energy that would otherwise be wasted or require continuous power input. When force assistance is needed, this recovered and stored energy is released to augment the motor's output. This discarding and recovering of energy in the form of elastic potential energy extends the effective power capacity of the portable power source without increasing its size, thereby supporting autonomy while working within power capacity limitations.
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
This solution enables robotic systems to achieve improved power-to-energy output ratios, reducing the size and power requirements of motors while maintaining or exceeding required force outputs, thus enhancing their efficiency and practicality for tasks that require force assistance.
Implementation Method 1
a quasi-passive elastic actuator that combines primary torque from an electric motor with augmented torque from a torsional coil spring
Implementation Method 2
augmented torque from a torsional coil spring
Data Source
AI summary
A method for operating a robotic joint of a robotic system comprising selectively operating a clutch mechanism of a clutched joint module in an engaged state to cause a quasi-passive elastic actuator to enter an elastic state, the clutched joint module operating about and defining a joint of the robotic system. The method comprising effecting a first rotation of the joint to cause the quasi-passive elastic actuator to store energy during at least a portion of the rotation of the joint. The method comprising effecting a second rotation of the joint and causing the stored energy from the quasi-passive elastic actuator to be released in the form of an augmented torque applied to an output member of the clutched joint module. The method comprising selectively operating the clutch mechanism in a disengaged state to cause the quasi-passive elastic actuator to enter an inelastic state. The method comprising effecting a third rotation of the joint, wherein the quasi-passive elastic actuator facilitates a free swing mode of the clutched joint module and the joint.