Design and experimental evaluation of a QFT contact task controller for electro‐hydraulic actuators
Bibliographic record
Abstract
Abstract This paper presents design and experimental evaluation of a robust contact task controller for an electro‐hydraulic actuator that operates under significant system uncertainties and nonlinearities. The designed controller allows the actuator to follow a free space trajectory, and upon contact with an uncertain environment exert a desired force, by stably passing through the transition phase from free space to constrained space. The scheme is essentially the combination of two distinct control laws that are individually designed for position regulation in free space and force regulation during sustained contact. Both controllers are designed, using a nonlinear approach within the framework of quantitative feedback theory (QFT), to satisfya priorispecified stability, tracking and disturbance rejection specifications. They are then combined with a simple switching law to form a contact task controller. Due to the existence of a switching, the resulting control system is non‐smooth. The stability of the controller is then analysed using an extended version of Lyapunov's second method under the condition of existence and uniqueness of Filippov's solution. Experiments, performed on a typical industrial hydraulic actuator, include motion through free space, contact with the environment and the transition between the two. The proposed QFT contact task control scheme enjoys the simplicity of fixed‐gain controllers, is easy to implement, requires very little computational effort, is robust to the variation of hydraulic functions as well as environmental stiffness, and results in responses with good performance in both transient and steady‐state periods. Additionally, the controller only requires measured contact force and actuator position as feedback; this makes the controller attractive for industrial implementation. Copyright © 2006 John Wiley & Sons, Ltd.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| 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 | 0.001 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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 itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".