As home robotics gains traction, robots are increasingly integrated into households, offering companionship and assistance. Quadruped robots, particularly those resembling dogs, have emerged as popular alternatives for traditional pets. However, user feedback highlights concerns about the noise these robots generate during walking at home, particularly the loud footstep sound. To address this issue, we propose a sim-to-real based reinforcement learning (RL) approach to minimize the foot contact velocity highly related to the footstep sound. Our framework incorporates three key elements: learning varying PD gains to actively dampen and stiffen each joint, utilizing foot contact sensors, and employing curriculum learning to gradually enforce penalties on foot contact velocity. Experiments demonstrate that our learned policy achieves superior quietness compared to a RL baseline and the carefully handcrafted Sony commercial controllers. Furthermore, the trade-off between robustness and quietness is shown. This research contributes to developing quieter and more user-friendly robotic companions in home environments.
Quadrupedal robots are conquering various applications in indoor and outdoor environments due to their capability to navigate challenging uneven terrains. Exteroceptive information greatly enhances this capability since perceiving their surroundings allows them to adapt their controller and thus achieve higher levels of robustness. However, sensors such as LiDARs and RGB cameras do not provide sufficient information to quickly and precisely react in a highly dynamic environment since they suffer from a bandwidth-latency trade-off. They require significant bandwidth at high frame rates while featuring significant perceptual latency at lower frame rates, thereby limiting their versatility on resource constrained platforms. In this work, we tackle this problem by equipping our quadruped with an event camera, which does not suffer from this tradeoff due to its asynchronous and sparse operation. In leveraging the low latency of the events, we push the limits of quadruped agility and demonstrate high-speed ball catching for the first time. We show that our quadruped equipped with an event-camera can catch objects with speeds up to 15 m/s from 4 meters, with a success rate of 83%. Using a VGA event camera, our method runs at 100 Hz on an NVIDIA Jetson Orin.
Phase equilibria in Fe-Mn-S and Fe-Cr-S ternary systems at 1843 K were investigated experimentally, respectively. The main characteristic of these two systems at 1843 K was confirmed to be a wide miscibility gap between two liquid phases: molten metal alloy phase and molten sulfide phase. Through metal/sulfide equilibrium method, activity of constituents in sulfide phase were determined in Fe-Mn-S and Fe-Cr-S systems separately. The activity curves of constituents in sulfide phase were estimated by utilizing regular solution model.
Multiwavelength erbium-doped fiber laser by means of phase modulation in a linear cavity configuration is presented. Stable multiwavelength lasing is achieved by applying any one of the waveforms of sine, square, sawtoothed, and triangular at a suitable frequency between 500 Hz to a few tens of kilohertz to the phase modulator. The output spectral lines power equalization is performed by adjusting the frequency to drive the all-fiber phase modulator and the polarization controller or dc offset voltage of a LiNbO/sub 3/ amplitude modulator, which is incorporated in a polarization-maintaining fiber Lyot-Sagnac filter.
Purpose: This study aimed to determine whether kinesiophobia mediates the relationship between low back pain (LBP), leg pain (LP), and leg dysesthesia (LD) and health-related quality of life (HRQOL) among Japanese individuals aged 65 years old and older treated with surgery for lumbar spinal stenosis (LSS). Patients and Methods: Data collection for this study took place between October 2019 and August 2020 at two Japanese medical facilities. Eligibility criteria for participants in this study were individuals aged 65 years or older and those who had undergone surgery for LSS at least more than one year ago. A self-administered questionnaire assessed the intensity of LBP, LP, and LD (numerical rating scale: NRS), HRQOL (EuroQol-5 Dimension-5 Levels: EQ-5D-5L), and kinesiophobia (Tampa Scale for Kinesiophobia-17 items: TSK-17). Mediation analysis using sex as a control variable was conducted. Results: Complete responses were obtained from 238 of 431 individuals (73.1 ± 5.1 years; 135 males and 103 females). The mediating effect of NRS scores for LBP, LP, and LD to EQ-5D-5L index on TSK-17 score was significant, respectively (LBP: − 0.007 [95% confidence interval − 0.012, − 0.004], p = 0.000; LP and LD: − 0.007 [− 0.011, − 0.004], p = 0.000). The strength of the association between NRS scores and EQ-5D-5L index decreased when the mediating effect of TSK-17 score (LBP: β = − 0.698 [− 0.792, − 0.603], p = 0.000 to β = − 0.616 [− 0.707, − 0.524], p = 0.000; LP: β = − 0.629 [− 0.729, − 0.529], p = 0.000 to β = − 0.539 [− 0.638, − 0.440], p = 0.000; LD: β = − 0.568 [− 0.675, − 0.460], p = 0.000 to β = − 0.482 [− 0.586, − 0.378], p = 0.000). The mediating effect of TSK score was greater in females than males. Conclusion: Kinophobia partially mediated the relationship between LBP, LP and LD, and HRQOL in Japanese aged 65 years and older after lumbar surgery. The mediating effect differed by sex. Keywords: pain, kinesiophobia, health-related quality of life, sex differences, lumbar spinal stenosis
Background: Working alliance between the physiotherapist and patient is important for successful treatment in physiotherapy. Working alliance can be measured by a 12-item self-reporting measure with 7-point Likert scale, the Working Alliance Inventory Short-Form Client (WAI-SC). Objectives: To develop a shorter version of the Japanese WAI-SC through examination of factor structure and test–retest reliability. Design: Survey. Method: A convenience sample of 118 outpatients with musculoskeletal disorders completed the WAI-SC immediately after the third consultation and 101 of them completed the WAI-SC immediately before the fourth consultation. Results/findings: Through investigations of internal consistency, test–retest reliability, and factor structure, a single structure was detected by excluding Item 4 and Item 10. Score calculation was also modified to dichotomous variables (Score 7 or other scores) due to serious ceiling effects, where >50% of responses were Score 7. A five-item questionnaire with dichotomous score rating (Modified WAI-SC Japanese musculoskeletal version) was developed through consideration of internal consistency and item-total correlation analysis. This questionnaire demonstrated adequate internal consistency (Cronbach's α = 0.88) and excellent test–retest reliability for each item (Cohen's κ for all > 0.4) and total scores (intraclass correlation coefficient = 0.84). Conclusions: The five-item Modified WAI-SC Japanese musculoskeletal version was developed with a single factor structure showing adequate internal consistency and excellent test–retest reliability.
Steel is not elemental iron but rather a group of iron-based alloys containing many elements, especially chromium, nickel, and molybdenum. Steel recycling is expected to promote efficient resource use. However, open-loop recycling of steel could result in quality loss of nickel and molybdenum and/or material loss of chromium. Knowledge about alloying element substance flow is needed to avoid such losses. Material flow analyses (MFAs) indicate the importance of steel recycling to recovery of alloying elements. Flows of nickel, chromium, and molybdenum are interconnected, but MFAs have paid little attention to the interconnected flow of materials/substances in supply chains. This study combined a waste input-output material flow model and physical unit input-output analysis to perform a simultaneous MFA for nickel, chromium, and molybdenum in the Japanese economy in 2000. Results indicated the importance of recovery of these elements in recycling policies for end-of-life (EoL) vehicles and constructions. Improvement in EoL sorting technologies and implementation of designs for recycling/disassembly at the manufacturing phase are needed. Possible solutions include development of sorting processes for steel scrap and introduction of easier methods for identifying the composition of secondary resources. Recovery of steel scrap with a high alloy content will reduce primary inputs of alloying elements and contribute to more efficient resource use.
Metallic impurities such as Al, Ca, Mg, Ti, and Fe in Si deteriorate solar cell efficiency to a large extent. To discuss the possibility and efficiency of impurity elimination process, the evaluation of their thermodynamic properties in molten Si are crucial. In the present work, the self-interaction parameters of Al, Ca, and Mg and interaction parameters between Ca–M (M: Al, Ti, Fe) in molten Si at 1723 K were investigated by applying a chemical equilibration technique for Si based alloys with Pb. The activity coefficients of Al and Ca in molten Si at 1723–1823 K were also determined by the Knudsen effusion method.
