The success of many space missions critically depends on human capabilities and performance. Yet, it is known that sensorimotor performance is degraded under conditions of weightlessness. Therefore, astronauts prepare for their missions in simulated weightlessness under water. In the present study, we investigated sensorimotor performance in simulated weightlessness (induced by shallow water immersion) and whether performance can be improved by choosing appropriate haptic settings of the human–machine interface (e.g., motion damping). Twenty-two participants performed basic aiming and tracking tasks with a force feedback joystick under water and on land and with different haptic settings of the joystick (no haptics, three spring stiffnesses, and two motion dampings). While higher resistive forces should be avoided for rapid aiming tasks in simulated weightlessness, tracking performance is best with higher motions damping in both land and water setups, although the performance losses due to water immersion cannot be compensated. The overall result pattern also provides insights into the causal mechanism behind the slowing effect during aiming motions and decreased accuracy of tracking motions in simulated weightlessness. Findings provide evidence that distorted proprioception due to altered muscle spindle activity seemingly is the main trigger of impaired sensorimotor performance in simulated weightlessness.
Demographic change and its various implications will be some of the biggest challenges to be faced by society and our health-care systems in the coming decades. While the number of people in need of caregiving is steadily growing in most industrial nations, the number of caregivers does not keep up with this increasing demand. Robotic assistance systems have the potential to mitigate this problem and support caregivers, people in need, and thereby the health-care systems in numerous ways. We present the concept and demonstrate first application scenarios of a holistic ecosystem for robotic assistants in caregiving. This ecosystem involves various robots to cover individual demands, and it combines several robotic technologies ranging from autonomous operation over shared-control to telepresencemodes, in order to deal with the wide variety of situations in the everyday life in caregiving. Working towards this ecosystem we have already implemented its core functionalities on the basis of our robotic prototypes and demonstrate exemplary scenarios to showcase the feasibility of the approach.
In this paper a trilateral Multi-Master-Single-Slave-System with control authority allocation between two human operators is proposed. The authority coefficient permits to slide the dominant role between the operators. They can simultaneously execute a task in a collaborative way or a trainee might haptically only observe the task, while an expert is in full control. The master devices are connected with each other and the slave robot peer to peer without a central processing unit in a equitable way. The system design is general in that it allows delayed communication and different coupling causalities between masters and slave, which can be located far from each other. The Time Domain Passivity Control Approach guarantees passivity of the network in the presence of communication delays. The methods presented are sustained with simulations and experiments using different authority coefficients.
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