Locking Force and Stiffness Oriented Design for an SMA-Actuated Miniaturized Lockable Prismatic Joint
Why this work is in the frame
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Bibliographic record
Abstract
Abstract Lockable mechanisms offer significant advantages for robotic systems, such as enabling effective energy management, motion reconfiguration, and stiffness adjustment. Crucially, when unlocked, these mechanisms allow the robot’s intended motion to proceed unimpeded. Upon locking, however, they enable motion reconfiguration and provide substantially enhanced load-bearing capacity (with increased stiffness). This capability allows them to be seamlessly integrated into existing robotic systems. In this study, we propose a novel lockable prismatic (P) joint that is modular, miniaturized, and capable of high load-bearing with high stiffness, based on compliant mechanisms and shape memory alloy (SMA) actuators. We first detail the joint's working principle and identify critical design parameters governing its locking performance and stiffness. Subsequently, we present an optimized design framework, illustrated with two design cases. Experimental validation confirms the joint's functionality, achieving a locking force of up to 180 N and a locked-state axial stiffness of 1400 N/mm. Furthermore, we demonstrate the joint’s practical utility through its application in a motion-reconfigurable, snake-like robotic arm with a compact design space and multiple motion modes. The arm can navigate into confined spaces like wing boxes using diverse motion modes and can lock into a high-stiffness configuration for stable end-loaded operations. Collectively, this research illuminates a pathway towards utilizing smart materials and compliant mechanisms to create high-performance lockable P joints, providing a locking and motion reconfiguration solution that is easy to design and use for robots of different sizes and load-carrying capabilities.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from it