4 research outputs found
Ball-and-socket joint pose estimation using magnetic field
Roboy 3.0 is an open-source tendon-driven humanoid robot that mimics the
musculoskeletal system of the human body. Roboy 3.0 is being developed as a
remote robotic body - or a robotic avatar - for humans to achieve remote
physical presence. Artificial muscles and tendons allow it to closely resemble
human morphology with 3-DoF neck, shoulders and wrists. Roboy 3.0 3-DoF joints
are implemented as ball-and-socket joints. While industry provides a clear
solution for 1-DoF joint pose sensing, it is not the case for the
ball-and-socket joint type. In this paper we present a custom solution to
estimate the pose of a ball-and-socket joint. We embed an array of magnets into
the ball and an array of 3D magnetic sensors into the socket. We then, based on
the changes in the magnetic field as the joint rotates, are able to estimate
the orientation of the joint. We evaluate the performance of two neural network
approaches using the LSTM and Bayesian-filter like DVBF. Results show that in
order to achieve the same mean square error (MSE) DVBFs require significantly
more time training and hyperparameter tuning compared to LSTMs, while DVBF cope
with sensor noise better. Both methods are capable of real-time joint pose
estimation at 37 Hz with MSE of around 0.03 rad for all three degrees of
freedom combined. The LSTM model is deployed and used for joint pose estimation
of Roboy 3.0's shoulder and neck joints. The software implementation and PCB
designs are open-sourced under
https://github.com/Roboy/ball_and_socket_estimatorComment: Accepted at the International Symposium on Robotics Research (ISRR)
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Dental Health and Mortality in People With End-Stage Kidney Disease Treated With Hemodialysis: A Multinational Cohort Study
Background Dental disease is more extensive in adults with chronic kidney disease, but whether dental health and behaviors are associated with survival in the setting of hemodialysis is unknown. Study Design Prospective multinational cohort. Setting & Participants 4,205 adults treated with long-term hemodialysis, 2010 to 2012 (Oral Diseases in Hemodialysis [ORAL-D] Study). Predictors Dental health as assessed by a standardized dental examination using World Health Organization guidelines and personal oral care, including edentulousness; decayed, missing, and filled teeth index; teeth brushing and flossing; and dental health consultation. Outcomes All-cause and cardiovascular mortality at 12 months after dental assessment. Measurements Multivariable-adjusted Cox proportional hazards regression models fitted with shared frailty to account for clustering of mortality risk within countries. Results During a mean follow-up of 22.1 months, 942 deaths occurred, including 477 cardiovascular deaths. Edentulousness (adjusted HR, 1.29; 95% CI, 1.10-1.51) and decayed, missing, or filled teeth score ≥ 14 (adjusted HR, 1.70; 95% CI, 1.33-2.17) were associated with early all-cause mortality, while dental flossing, using mouthwash, brushing teeth daily, spending at least 2 minutes on oral hygiene daily, changing a toothbrush at least every 3 months, and visiting a dentist within the past 6 months (adjusted HRs of 0.52 [95% CI, 0.32-0.85], 0.79 [95% CI, 0.64-0.97], 0.76 [95% CI, 0.58-0.99], 0.84 [95% CI, 0.71-0.99], 0.79 [95% CI, 0.65-0.95], and 0.79 [95% CI, 0.65-0.96], respectively) were associated with better survival. Results for cardiovascular mortality were similar. Limitations Convenience sample of clinics. Conclusions In adults treated with hemodialysis, poorer dental health was associated with early death, whereas preventive dental health practices were associated with longer survival