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Delays in Admittance-Controlled Haptic Devices Make Simulated Masses Feel Heavier.

ABSTRACT: In an admittance-controlled haptic device, input forces are used to calculate the movement of the device. Although developers try to minimize delays, there will always be delays between the applied force and the corresponding movement in such systems, which might affect what the user of the device perceives. In this experiment we tested whether these delays in a haptic human-robot interaction influence the perception of mass. In the experiment an admittance-controlled manipulator was used to simulate various masses. In a staircase design subjects had to decide which of two virtual masses was heavier after gently pushing them leftward with the right hand in mid-air (no friction, no gravity). The manipulator responded as quickly as possible or with an additional delay (25 or 50 ms) to the forces exerted by the subject on the handle of the haptic device. The perceived mass was ~10% larger for a delay of 25 ms and ~20% larger for a delay of 50 ms. Based on these results, we estimated that the delays that are present in nowadays admittance-controlled haptic devices (up to 20ms) will give an increase in perceived mass which is smaller than the Weber fraction for mass (~10% for inertial mass). Additional analyses showed that the subjects' decision on mass when the perceptual differences were small did not correlate with intuitive variables such as force, velocity or a combination of these, nor with any other measured variable, suggesting that subjects did not have a consistent strategy during guessing or used other sources of information, for example the efference copy of their pushes.

SUBMITTER: Kuling IA

PROVIDER: S-EPMC4567313 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Delays in Admittance-Controlled Haptic Devices Make Simulated Masses Feel Heavier.

Kuling Irene A IA Smeets Jeroen B J JB Lammertse Piet P Onneweer Bram B Mugge Winfred W

PloS one 20150911 9

In an admittance-controlled haptic device, input forces are used to calculate the movement of the device. Although developers try to minimize delays, there will always be delays between the applied force and the corresponding movement in such systems, which might affect what the user of the device perceives. In this experiment we tested whether these delays in a haptic human-robot interaction influence the perception of mass. In the experiment an admittance-controlled manipulator was used to sim ...[more]

PMID: 26361353

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Project description:The transformation toward more sustainable food choices may be supported by an education for sustainable nutrition. In schools, biology teachers play a key role in educating students as sustainability change makers, as biology lessons provide various opportunities to deal with ESD-topics such as sustainable nutrition. Teachers' classroom practices may be influenced by their personal choices regarding sustainable nutrition. Additionally, students may see their teachers as role models for sustainable behavior. This presents the risk of students adopting teachers' beliefs and behaviors without reflection. Teaching sustainable nutrition is therefore in potential conflict with indoctrinating young people toward sustainable diets. To date, no studies have addressed the perceived risk of indoctrination in the context of teaching sustainable nutrition in relation to teachers' personal beliefs, behaviors, and teaching practices. Therefore, this study explored whether biology teachers themselves perceive a risk of indoctrination when teaching sustainable nutrition, and what methods they use for teaching it in a non-indoctrinating way. For this purpose, we conducted semi-structured interviews with seven in-service biology teachers from high schools in Germany. Data for this explorative qualitative study were collected from July to October 2021 using convenience sampling. These were analyzed by qualitative coding and content analysis. The preliminary results of this study show that participants recognize a high risk of indoctrination when teaching sustainable nutrition, primarily due to their own teaching actions, such as deciding whether to reveal their own dietary choices to students. While some participants believed teachers must be restrained, others thought that open communication about personal choices could benefit student decision-making skills. In terms of avoiding indoctrination when teaching sustainable nutrition, participants advocated for student-centered and multi-perspective teaching approaches. Based on the findings, initial implications for further research and teacher training are discussed.

Project description:BackgroundHuntington disease (HD) is an inherited genetic disorder that results in the death of brain cells. HD symptoms generally start with subtle changes in mood and mental abilities; they then degenerate progressively, ensuing a general lack of coordination and an unsteady gait, ultimately resulting in death. There is currently no cure for HD. Walking cued by an external, usually auditory, rhythm has been shown to steady gait and help with movement coordination in other neurological conditions. More recently, work with other neurological conditions has demonstrated that haptic (ie, tactile) rhythmic cues, as opposed to audio cues, offer similar improvements when walking. An added benefit is that less intrusive, more private cues are delivered by a wearable device that leaves the ears free for conversation, situation awareness, and safety. This paper presents a case study where rhythmic haptic cueing (RHC) was applied to one person with HD. The case study has two elements: the gait data we collected from our wearable devices and the comments we received from a group of highly trained expert physiotherapists and specialists in HD.ObjectiveThe objective of this case study was to investigate whether RHC can be applied to improve gait coordination and limb control in people living with HD. While not offering a cure, therapeutic outcomes may delay the onset or severity of symptoms, with the potential to improve and prolong quality of life.MethodsThe approach adopted for this study includes two elements, one quantitative and one qualitative. The first is a repeated-measures design with three conditions: before haptic rhythm (ie, baseline), with haptic rhythm, and after exposure to haptic rhythm. The second element is an in-depth interview with physiotherapists observing the session.ResultsIn comparison to the baseline, the physiotherapists noted a number of improvements to the participant's kinematics during her walk with the haptic cues. These improvements continued in the after-cue condition, indicating some lasting effects. The quantitative data obtained support the physiotherapists' observations.ConclusionsThe findings from this small case study, with a single participant, suggest that a haptic metronomic rhythm may have immediate, potentially therapeutic benefits for the walking kinematics of people living with HD and warrants further investigation.

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Delays in Admittance-Controlled Haptic Devices Make Simulated Masses Feel Heavier.

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Delays in Admittance-Controlled Haptic Devices Make Simulated Masses Feel Heavier.

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