Force Perception Research Articles

Type-2 Fuzzy logic based time-delayed shared control in online-switching tele-operated and autonomous systems

This paper develops a novel shared control scheme for online-switching tele-operated and autonomous system with time-varying delays. Type-2 Takagi–Sugeno (T–S) fuzzy model is used to describe the dynamics of master and slave robots in this system. A novel non-singular fast terminal siding mode (NFTSM)-based algorithm combined with an extended wave-based time domain passivity approach (TDPA) is presented to enhance the master–slave motion synchronization in the tele-operated mode and reference-slave motion synchronization in the autonomous mode, while simultaneously ensuring the stability of the overall system in the presence of arbitrary time delays. In addition, based on the Type-2 Fuzzy model, a new torque observer is designed to estimate the external torques and then the torque tracking method is employed in the control laws to let the slave apply the designated force to further improve the operator’s force perception for the environment. The stability of the closed-loop system is proven using the Lyapunov–Krasovskii functions. Finally, experiments using two haptic devices prove the superiority of the proposed strategy.

Evaluation of human force perception properties in driving operations by the limbs

Evaluation of human force perception properties in driving operations by the limbs

Enhancement of the Force Perception on the Wrist under the Hanger Reflex by Presenting Vibration

Enhancement of the Force Perception on the Wrist under the Hanger Reflex by Presenting Vibration

Self-imposed pressure or organizational norms? Further examination of the construct of workplace telepressure.

Information and communication technologies (ICTs) are rapidly becoming indispensable organizational tools. Though the benefits of such technologies have been trumpeted, recent research has examined the unique pressures that may be introduced through the lens of a construct called workplace telepressure, defined as an urge for and preoccupation with quickly responding to ICTs (e.g., email). The current study further explores the workplace telepressure construct as a unique contributor to measures of workplace well-being over and above perceived workplace demands and individual differences, introducing new constructs into the study of workplace telepressure. Furthermore, the study critically evaluates the term "telepressure" as applied to the underlying construct, as "pressure" may connote a perception of external force being placed on an individual, whereas the definition offered by past research identifies a preoccupation and urge to respond immediately to ICT messages, which may be internally generated. Finally, the ability of workplace telepressure to account for unique variance in workplace subjective well-being measures is investigated.

Unpowered Sensorimotor-Enhancing Suit Reduces Muscle Activation and Improves Force Perception

Studies suggest that the level of muscle activation may influence force reproduction. The purpose of this study was to develop a sensorimotor-enhancing suit (SEnS)—unpowered assistive clothing without actuators or electrical devices—and to examine its efficacy for reducing voluntary muscle activation and improving force reproduction in the upper limb in healthy young adults. The SEnS was made of elastic fabric and designed to produce assistive shoulder flexion moment that can partially mitigate the required activation of the user's shoulder flexor muscles. A series of human experiments were then conducted in healthy young adults. As a proof of concept, reduction in force reproduction performance of the shoulder moment was confirmed with mitigation of the shoulder moment by using an external string. To examine the efficacy of the SEnS, voluntary muscle activation and force reproduction performance was examined with and without using the SEnS, by comparing the amount of activation in the shoulder flexor muscles and the error in force reproduction in the upper limb. The results showed that wearing SEnS reduced muscle activation and force reproduction error. These results suggest that the accuracy of force reproduction can be improved substantially by partially mitigating the shoulder moment and associated voluntary muscle activation, using the SEnS.

Force illusions and drifts observed during muscle vibration.

We explored predictions of a scheme that views position and force perception as a result of measuring proprioceptive signals within a reference frame set by ongoing efferent process. In particular, this hypothesis predicts force illusions caused by muscle vibration and mediated via changes in both afferent and efferent components of kinesthesia. Healthy subjects performed accurate steady force production tasks by pressing with the four fingers of one hand (the task hand) on individual force sensors with and without visual feedback. At various times during the trials, subjects matched the perceived force using the other hand. High-frequency vibration was applied to one or both of the forearms (over the hand and finger extensors). Without visual feedback, subjects showed a drop in the task hand force, which was significantly smaller under the vibration of that forearm. Force production by the matching hand was consistently higher than that of the task hand. Vibrating one of the forearms affected the matching hand in a manner consistent with the perception of higher magnitude of force produced by the vibrated hand. The findings were consistent between the dominant and nondominant hands. The effects of vibration on both force drift and force mismatching suggest that vibration led to shifts in both signals from proprioceptors and the efferent component of perception, the referent coordinate and/or coactivation command. The observations fit the hypothesis on combined perception of kinematic-kinetic variables with little specificity of different groups of peripheral receptors that all contribute to perception of forces and coordinates. NEW & NOTEWORTHY We show that vibration of hand/finger extensors produces consistent errors in finger force perception. Without visual feedback, finger force drifted to lower values without a drift in the matching force produced by the other hand; hand extensor vibration led to smaller finger force drift. The findings fit the scheme with combined perception of kinematic-kinetic variables and suggest that vibration leads to consistent shifts of the referent coordinate and, possibly, of coactivation command to the effector.

Evaluation of the Perceptual Characteristics of a Force Induced by Asymmetric Vibrations.

This paper describes the perceptual characteristics of a sense of a force induced by asymmetric vibration using a vibration speaker-type non-grounded haptic interface. We confirm that the vibration speaker generates a perceived force that pulls or pushes a user's hand in a particular direction when an asymmetric amplitude signal that is generated by inverting a part of a sine wave is input. In this paper, to verify the system with respect to various factors of force perception caused by asymmetric vibration, we conducted six experiments and the following results were obtained. (1) The force vector can be controlled by reversing the asymmetric waves. (2) By investigating the physical characteristics of the vibration, asymmetric vibration was confirmed. (3) The presentation of vibration in the shear direction on the finger pad is effective. (4) The point of subjective equality of the perceived force can be controlled by up to 0.43 N by changing the amplitude voltage of the input signals. (5) The minimum stimulation time required for force perception is 66.7 ms. (6) When the vibration is continuously presented for 40 to 50 s, the perceived force decreases because of adaptation. Hence, we confirmed that we can control both the direction and magnitude of the reaction force by changing the input signal of the vibration speaker.

Type-2 Fuzzy Modeling and Control for Bilateral Teleoperation System With Dynamic Uncertainties and Time-Varying Delays

This paper develops data-driven Type-2 Takagi–Sugeno (T–S) fuzzy modeling and control for bilateral teleoperation with dynamic uncertainties and time-varying delays. The Type-2 T–S fuzzy model identified based on input–output data samples describes the nonlinear teleoperation system by a weighted sum of a group of linear local models, which offers a platform to design robust control algorithms by means of mature linear theories. The fuzzy-model-based four-channel control laws are proposed to guarantee the motion synchronization and enhance the operator's force perception for the environment when the time-varying delays and large dynamic uncertainties, especially the gravity of a heavy end effector of the slave, exist. Markov processes are applied to model the time delays. The stability of the closed-loop system is proved by using the Lyapunov–Krasovskii functions. All the conditions are expressed as linear-matrix inequalities (LMI). By using the MATLAB LMI toolbox, the optimized control gains for each of the fuzzy rules are derived to achieve the optimal performance. Finally, experiments based on an experimental platform consisting of two haptic devices prove the superiority of the proposed strategy through comparison with previous work.

Perception of force and stiffness in the presence of low-frequency haptic noise.

ObjectiveThis work lays the foundation for future research on quantitative modeling of human stiffness perception. Our goal was to develop a method by which a human’s ability to perceive suprathreshold haptic force stimuli and haptic stiffness stimuli can be affected by adding haptic noise.MethodsFive human participants performed a same-different task with a one-degree-of-freedom force-feedback device. Participants used the right index finger to actively interact with variations of force (∼5 and ∼8 N) and stiffness (∼290 N/m) stimuli that included one of four scaled amounts of haptically rendered noise (None, Low, Medium, High). The haptic noise was zero-mean Gaussian white noise that was low-pass filtered with a 2 Hz cut-off frequency; the resulting low-frequency signal was added to the force rendered while the participant interacted with the force and stiffness stimuli.ResultsWe found that the precision with which participants could identify the magnitude of both the force and stiffness stimuli was affected by the magnitude of the low-frequency haptically rendered noise added to the haptic stimulus, as well as the magnitude of the haptic stimulus itself. The Weber fraction strongly correlated with the standard deviation of the low-frequency haptic noise with a Pearson product-moment correlation coefficient of ρ > 0.83. The mean standard deviation of the low-frequency haptic noise in the haptic stimuli ranged from 0.184 N to 1.111 N across the four haptically rendered noise levels, and the corresponding mean Weber fractions spanned between 0.042 and 0.101.ConclusionsThe human ability to perceive both suprathreshold haptic force and stiffness stimuli degrades in the presence of added low-frequency haptic noise. Future work can use the reported methods to investigate how force perception and stiffness perception may relate, with possible applications in haptic watermarking and in the assessment of the functionality of peripheral pathways in individuals with haptic impairments.

Women and leadership: challenges and opportunities in Saudi higher education

PurposeThe purpose of this paper is to examine women managers’ perceptions of forces influencing their career progression to leadership positions in Saudi Arabian higher education (HE).Design/methodology/approachA qualitative, interpretive approach is adopted for analysing in-depth interviews with women managers in Saudi HE.FindingsThe findings of this study provide an in-depth understanding of Saudi women’s experience in management in HE. This study shows that women face a number of challenges preventing them from achieving equitable representation in leadership positions; conversely, they do have some opportunities which help them in their careers. Additionally, it provides more explanation of how the macro factors trickle down to the organizational level to shape organizational process and practices, and have an impact on women accessing leadership positions. Furthermore, this study suggests that socio-cultural background does matter when studying women in management in the Saudi context.Research limitations/implicationsThe paper, mainly focussing on women managers in Saudi HE, gives a clear picture of women’s careers and influencing factors.Practical implicationsThe research has implications for government and other related institutions to formulate effective policies and appropriate strategies to help Saudi women access leadership posts.Originality/valueThe novelty of this paper is in its focus on the under-researched topic of careers of Saudi women managers. The paper is also valuable as it emphasizes the societal context for researchers wishing to study women’s careers in the Arab world.

Sales Manager Influence Of New Product Adoption By Their Salesforce: A Theoretical Perspective

New product introductions are an important part of the success of many organizations, and they often hinge on the perceptions of the sales force. In turn, much of sales person perceptions are derived from managerial guidance and input. Although the extant literature has investigated some of the antecedents to the adoption of new products by salespeople, very little attention has been paid to the impact of the sales manager over this process. Using elements of social information processing, this paper explores how sales managers can exert influence over new product adoption by their salespeople.

Ipsilateral Scapular Cutaneous Anchor System: An alternative for the harness in body-powered upper-limb prostheses.

Background:Body-powered prosthesis users frequently complain about the poor cosmesis and comfort of the traditional shoulder harness. The Ipsilateral Scapular Cutaneous Anchor System offers an alternative, but it remains unclear to what extent it affects the perception and control of cable operation forces compared to the traditional shoulder harness.Objective:To compare cable force perception and control with the figure-of-nine harness versus the Ipsilateral Scapular Cutaneous Anchor System and to investigate force perception and control at different force levels.Study design:Experimental trial.Methods:Ten male able-bodied subjects completed a cable force reproduction task at four force levels in the range of 10–40 N using the figure-of-nine harness and the Anchor System. Perception and control of cable operating forces were quantified by the force reproduction error and the force variability.Results:In terms of force reproduction error and force variability, the subjects did not behave differently when using the two systems. The smallest force reproduction error and force variability were found at the smallest target force level of 10 N.Conclusion:The Anchor System performs no differently than the traditional figure-of-nine harness in terms of force perception and control, making it a viable alternative. Furthermore, users perceive and control low operation forces better than high forces.Clinical relevanceThe Ipsilateral Scapular Cutaneous Anchor System offers an alternative for the traditional harness in terms of cable operation force perception and control and should therefore be considered for clinical use.Low cable operation forces increase the perception and control abilities of users.

A produção desejante na cultura afro-brasileira: uma leitura de Barravento

O presente artigo pretende fazer uma leitura do filme Barravento, de Glauber Rocha, de modo a evidenciar aspectos analíticos para além da dialética materialista e do jogo fetichista da cultura afro-brasileira. Na multiplicidade de sentidos que se encontram na composição das cenas e imagens desta obra, existe uma crítica ao materialismo vulgar dentro do próprio sistema de signos do devir-primitivo. Isto nos leva a postular as ambiguidades próprias da vida brasileira no entrechoque do arcaico com o moderno, evidenciando os arcaísmos próprios da modernidade ilustrada e engajada, bem como uma forte percepção das forças sociais vitais na cultura primitiva, capazes inclusive de resistir frontalmente à axiomatização capitalista. Os autores que fornecem as ferramentas conceituais para esta articulação são Deleuze e Guattari em seu O Anti-Édipo.

Short-term follow-up of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis: a pilot assessment

BackgroundWhen teeth are extracted, sensory function is decreased by a loss of periodontal ligament receptions. When replacing teeth by oral implants, one hopes to restore the sensory feedback pathway as such to allow for physiological implant integration and optimized oral function with implant-supported prostheses. What remains to be investigated is how to adapt to different oral rehabilitations.The purpose of this pilot study was to assess four aspects of masticatory adaptation after rehabilitation with an immediately loaded implant-supported prosthesis and to observe how each aspect will recover respectively.MethodsEight participants with complete dentures were enrolled. They received an implant-supported acrylic resin provisional bridge, 1 day after implant surgery. Masticatory adaptation was examined by assessing occlusal contact, approximate maximum bite force, masticatory efficiency of gum-like specimens, and food hardness perception.ResultsOcclusal contact and approximate maximum bite force were significantly increased 3 months after implant rehabilitation, with the bite force gradually building up to a 72% increase compared to baseline. Masticatory efficiency increased by 46% immediately after surgery, stabilizing at around 40% 3 months after implant rehabilitation. Hardness perception also improved, with a reduction of the error rate by 16% over time.ConclusionsThis assessment demonstrated masticatory adaptation immediately after implant rehabilitation with improvements noted up to 3 months after surgery and rehabilitation. It was also observed that, despite gradually improved bite force in all patients, masticatory efficiency and food hardness perception did not necessarily follow this tendency. The findings in this pilot may also be used to assess adaptation of oral function after implant rehabilitation by studying the combined outcome of four tests (occlusal contact, maximum bite force, masticatory efficiency, and food hardness perception).

Kant on Impenetrability, Touch, and the Causal Content of Perception

AbstractIt is well known that Kant claims that causal judgments, including judgments about forces, must have an a priori basis. It is less well known that Kant claims that we can perceive the repulsive force of bodies (their impenetrability) through the sense of touch. Together, these claims present an interpretive puzzle, since they appear to commit Kant to both affirming and denying that we can have perceptions of force. My first aim is to show that both sides of the puzzle have deep roots in Kant's philosophy. My second aim is to present three potential solutions to the puzzle and show that each faces problems.

TREK-2 Has an Asymmetrical Response to Force Changes in the Membrane

Perception of force is a key component in our sensation of touch, hearing and pain as well as in regulation of blood and osmotic pressures, but unlike the well-described nature of taste and odorant receptors and the photoreceptors in the eye, we have not yet a clear idea of how this sense operate at the molecular level. Fundamental to the concept is that force must be translated into electrical conductance, that is perceived by the nervous system, and we believe this translation occur through the action of mechanosensitive ion channels. Recently it has been demonstrated that eukaryotic mechanosensitive channels, just like their prokaryotic counterparts, directly sense force changes in the lipid bilayers, so now the important question is: how does membrane modulation couple to channel activity? To address this question we use purified mechanosensitive TREK-2 channels, which we reconstitute into planar lipid patches at a concentration that allow us to study channel activity at the single molecule level. We find that the reconstituted channels have a random orientation, and that we can clearly distinguish between the two possible orientations by analyzing electrophysiological characteristics as conductance and open dwell times. To investigate the sensitivity of the channels to mechanical modulation, we apply different degrees of negative or positive pressure to the patches, and analyze how such stimulations affect the activity of differently oriented channels. With this approach we can demonstrate that mechanical activation of TREK-2 depends on the direction of the pressure pulse, i.e. one orientation is activated only by negative pressure while the other orientation is activated only by positive pressure. We carefully suggest that these results demonstrate that TREK-2 channels are sensitive to the direction of membrane curvature. Furthermore we are in the process of deducing a kinetic model that describes TREK-2 activation by pressure.

The Influence of Police Profanity on Public Perception of Excessive Force

Previous research has examined elements of police performance impacting community policing and police-citizen relationships, but no study has considered the impact of police use of profanity during arrest on public rating of force. Police profanity may negatively bias police-citizen interactions, and this bias could shape later interactions with community members, impact the quality of police-community relations, or even result in public outcry over excessive use of force. The aim of this study was to determine whether officer use of profanity during arrest led to public perception of excessive force and to examine whether gender of the officer or subject affected this relation. Force was evaluated as more excessive when profanity was used, when the subject was a female, and when the officer was a female. Participants who rated force as excessive had significantly more negative attitudes about police and police use of force. These findings have direct implications for police training and suggest that if police avoid the use of profanity, this could result in more positive relationships with the public and fewer allegations of excessive force. Future researchers should further evaluate the nature and impact of gender biases against female police, as they may contribute to reduced opportunities, less frequent promotion, and reduced self-efficacy in female officers.

Operational Forces soldiers’ perceptions of attributes and skills for career success

Orientation: A career within the South African Operational Forces is physically, mentally and emotionally challenging. It is a diverse working environment with its own organisational culture and unique challenges.Research purpose: The aim of the study was to explore the perceptions of Operational Forces soldiers regarding the unique requirements that facilitated their career success.Motivation for the study: A low percentage of candidates successfully complete the Operational Forces training. The financial implications of training candidates make it important to be able to identify candidates who have the potential to be successful, early on in the process.Research design, approach and method: Data were collected through a self-administered qualitative survey (n = 98). All participants were permanent Operational Forces soldiers with varying ranks and years of experience. The data were thematically analysed in order to identify themes and specific attributes and skills associated with a successful career in the Operational Forces.Main findings: A number of themes emerged from the data, each of which contributed to our understanding of the research question. The themes included self-concept, personality, interests, cognitive and physical factors.Practical and managerial implications: The research findings may help to inform decisions about approaches, practices and methodologies of the South African Operational Forces recruitment and selection process. Results also provide military organisations with the key characteristics to consider when identifying candidates with the highest potential for successful careers.Contribution and value-add: The study extends previous career success research by contributing an additional base of information regarding career success and factors that are perceived to influence it.

Force Perception Thresholds in Cochlear Implantation Surgery

Tissue trauma is a frequent complication of cochlear implantation (CI) surgery, but the relationship between intracochlear trauma, electrode insertion forces, and surgeons' ability to perceive these forces is poorly understood. In this study, we simulated CI surgery using a benchtop apparatus to repeatedly apply small forces to the subjects' hands while reducing the variability in their hand movements. We used a psychophysical testing procedure to estimate the force perception thresholds of 10 otologic surgeons and found a median threshold of 20.4 mN. The results suggest that surgeons have the capability to sense at least some insertion forces and are likely to perceive severe trauma such as occurs when the electrode crosses from one scala to the other.

Deficits in Proprioception Measured in Children With Somatodyspraxia

Abstract Date Presented 4/8/2016 We demonstrate new quantitative methods for assessing proprioception. These assessments show that some children with dyspraxia have difficulties with force perception and joint position sense. Quantitative assessments enable therapists to accurately isolate proprioceptive difficulties in children. Primary Author and Speaker: Virginia Way Tong Chu Additional Author and Speaker: Stefanie Bodison