65 research outputs found
Optimal energy shaping via neural approximators
We introduce optimal energy shaping as an enhancement of classical passivity-based control methods. A promising feature of passivity theory, alongside stability, has traditionally been claimed to be intuitive performance tuning along the execution of a given task. However, a systematic approach to adjust performance within a passive control framework has yet to be developed, as each method relies on few and problem-specific practical insights. Here, we cast the classic energy-shaping control design process in an optimal control framework; once a task-dependent performance metric is defined, an optimal solution is systematically obtained through an iterative procedure relying on neural networks and gradient-based optimization. The proposed method is validated on state-regulation tasks
The influence of performance on action-effect integration in sense of agency
Sense of agency refers to the subjective feeling of being able to control an outcome through one’s own actions or will. Prior studies have shown that both sensory processing (e.g., comparisons between sensory feedbacks and predictions basing on one’s motor intentions) and high-level cognitive/constructive processes (e.g., inferences based on one’s performance or the consequences of one’s actions) contribute to judgments of sense of agency. However, it remains unclear how these two types of processes interact, which is important for clarifying the mechanisms underlying sense of agency. Thus, we examined whether performance-based inferences influence action-effect integration in sense of agency using a delay detection paradigm in two experiments. In both experiments, participants pressed left and right arrow keys to control the direction in which a moving dot was travelling. The dot’s response delay was manipulated randomly on 7 levels (0–480 ms) between the trials; for each trial, participants were asked to judge whether the dot response was delayed and to rate their level of agency over the dot. In Experiment 1, participants tried to direct the dot to reach a destination on the screen as quickly as possible. Furthermore, the computer assisted participants by ignoring erroneous commands for half of the trials (assisted condition), while in the other half, all of the participants’ commands were executed (self-control condition). In Experiment 2, participants directed the dot as they pleased (without a specific goal), but, in half of the trials, the computer randomly ignored 32% of their commands (disturbed condition) rather than assisted them. The results from the two experiments showed that performance enhanced action-effect integration. Specifically, when task performance was improved through the computer’s assistance in Experiment 1, delay detection was reduced in the 480-ms delay condition, despite the fact that 32% of participants’ commands were ignored. Conversely, when no feedback on task performance was given (as in Experiment 2), the participants reported greater delay when some of their commands were randomly ignored. Furthermore, the results of a logistic regression analysis showed that the threshold of delay detection was greater in the assisted condition than in the self-control condition in Experiment 1, which suggests a wider time window for action-effect integration. A multivariate analysis also revealed that assistance was related to reduced delay detection via task performance, while reduced delay detection was directly correlated with a better sense of agency. These results indicate an association between the implicit and explicit aspects of sense of agency
Performance Comparison between Consequent-Pole and Inset Modular Permanent Magnet Machines
This paper proposes some consequent-pole modular
permanent magnet machines with different flux gap widths
and slot/pole number combinations. The corresponding inset
modular permanent magnet machines having the same
magnet volume are also presented for comparison. It has been
demonstrated that the output torques of the consequent pole
modular machines are always higher than those of the inset
modular machines regardless of flux gap widths and slot/pole
number combinations. Other electromagnetic performances
such as back-EMF, cogging torque, and iron losses, etc. are
calculated by 2D FEA software and compared as well. The
advantages and disadvantages of consequent and inset
modular permanent magnet machines are summarized in this
paper
Foliar Morphology And Anatomy Of The Gigantopterid Plant Delnortea Abbottiae, From The Lower Permian Of West Texas
Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142005/1/ajb214202.pd
Study on a Transportation and Emplacement System of Pre-Assembled EBS Module for HLW Geological Disposal(Thermal Engineering)
Intelligent Cruise Control of Circulating Multi-Robot Effective for Congestion(<Special Issue>TRANSLOG2009/J-RAIL2009)
Motion planning of multiple mobile robots for cooperative manipulation and transportation
Real-Time Vision-Based Stiffness Mapping
This paper presents new findings concerning a hand-held stiffness probe for the medical diagnosis of abnormalities during palpation of soft-tissue. Palpation is recognized by the medical community as an essential and low-cost method to detect and diagnose disease in soft-tissue. However, differences are often subtle and clinicians need to train for many years before they can conduct a reliable diagnosis. The probe presented here fills this gap providing a means to easily obtain stiffness values of soft tissue during a palpation procedure. Our stiffness sensor is equipped with a multi degree of freedom (DoF) Aurora magnetic tracker, allowing us to track and record the 3D position of the probe whilst examining a tissue area, and generate a 3D stiffness map in real-time. The stiffness probe was integrated in a robotic arm and tested in an artificial environment representing a good model of soft tissue organs; the results show that the sensor can accurately measure and map the stiffness of a silicon phantom embedded with areas of varying stiffness
Effect of varus gait on anterior cruciate ligament: to clarify mechanism of pathogenesis of knee osteoarthritis
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