Background Advanced age and brain damage have been reported to increase the propensity to gaze do... more Background Advanced age and brain damage have been reported to increase the propensity to gaze down while walking, a behavior that is thought to enhance stability through anticipatory stepping control. Recently, downward gazing (DWG) has been shown to enhance postural steadiness in healthy adults, suggesting that it can also support stability through a feedback control mechanism. These results have been speculated to be the consequence of the altered visual flow when gazing down. The main objective of this cross-sectional, exploratory study was to investigate whether DWG also enhances postural control in older adults and stroke survivors, and whether such effect is altered with aging and brain damage. Methods Posturography of older adults and stroke survivors, performing a total of 500 trials, was tested under varying gaze conditions and compared with a cohort of healthy young adults (375 trials). To test the involvement of the visual system we performed spectral analysis and compared the changes in the relative power between gaze conditions. Results Reduction in postural sway was observed when participants gazed down 1 and 3 meters ahead whereas DWG towards the toes decreased steadiness. These effects were unmodulated by age but were modulated by stroke. The relative power in the spectral band associated with visual feedback was significantly reduced when visual input was unavailable (eyes-closed condition) but was unaffected by the different DWG conditions. Conclusions Like young adults, older adults and stroke survivors better control their postural sway when gazing down a few steps ahead, but extreme DWG can impair this ability, especially in people with stroke.
This study explored pedestrians’ understanding of Fully Autonomous Vehicles (FAVs) intention to s... more This study explored pedestrians’ understanding of Fully Autonomous Vehicles (FAVs) intention to stop and what influences pedestrians’ decision to cross the road over time, i.e., learnability. Twenty participants saw fixed simulated urban road crossing scenes with a single FAV on the road as if they were pedestrians intending to cross. Scenes differed from one another in the FAV’s, distance from the crossing place, its physical size, and external Human-Machine Interfaces (e-HMI) message by background color (red/green), message type (status/advice), and presentation modality (text/symbol). Eye-tracking data and decision measurements were collected. Results revealed that pedestrians tend to look at the e-HMI before making their decision. However, they did not necessarily decide according to the e-HMIs’ color or message type. Moreover, when they complied with the e-HMI proposition, they tended to hesitate before making the decision. Overall, a learning effect over time was observed in a...
To explore cognitive strategies clinicians apply while performing a medication reconciliation tas... more To explore cognitive strategies clinicians apply while performing a medication reconciliation task, handling incomplete and conflicting information. Background: Medication reconciliation is a method clinicians apply to find and resolve inconsistencies in patients' medications and medical conditions lists. The cognitive strategies clinicians use during reconciliation are unclear. Controlled lab experiments can explore how clinicians make sense of uncertain, missing, or conflicting information and therefore support the development of a human performance model. We hypothesize that clinicians apply varied cognitive strategies to handle this task and that profession and experience affect these strategies. Method: 130 clinicians participated in a tablet-based experiment conducted in a large American teaching hospital. They were asked to simulate medication reconciliation using a card sorting task (CaST) to organize medication and medical condition lists of a specific clinical case. Later on, they were presented with new information and were asked to add it to their arrangements. We quantitatively and qualitatively analyzed the ways clinicians arranged patient information. Results: Four distinct cognitive strategies were identified ("Conditions first": n = 76 clinicians, "Medications first": n = 7, "Crossover": n = 17, and "Alternating": n = 10). The strategy clinicians applied was affected by their experience (p = .02) but not by their profession. At the appearance of new information, clinicians moved medication cards more frequently (75.2 movements vs. 49.6 movements, p < .001), suggesting that they match medications to medical conditions. Conclusion: Clinicians apply various cognitive strategies while reconciling medications and medical conditions. Application: Clinical information systems should support multiple cognitive strategies, allowing flexibility in organizing information.
Data on individual feed intake of dairy cows, an important variable for farm management, are curr... more Data on individual feed intake of dairy cows, an important variable for farm management, are currently unavailable in commercial dairies. A real-time machine vision system including models that are able to adapt to multiple types of feed was developed to predict individual feed intake of dairy cows. Using a Red-Green-Blue-Depth (RGBD) camera, images of feed piles of two different feed types (lactating cows' feed and heifers' feed) were acquired in a research dairy farm, for a range of feed weights under varied configurations and illuminations. Several models were developed to predict individual feed intake: two Transfer Learning (TL) models based on Convolutional Neural Networks (CNNs), one CNN model trained on both feed types, and one Multilayer Perceptron and Convolutional Neural Network model trained on both feed types, along with categorical data. We also implemented a statistical method to compare these four models using a Linear Mixed Model and a Generalised Linear Mixed Model, showing that all models are significantly different. The TL models performed best and were trained on both feeds with TL methods. These models achieved Mean Absolute Errors (MAEs) of 0.12 and 0.13 kg per meal with RMSE of 0.18 and 0.17 kg per meal for the two different feeds, when tested on varied data collected manually in a cowshed. Testing the model with actual cows' meals data automatically collected by the system in the cowshed resulted in a MAE of 0.14 kg per meal and RMSE of 0.19 kg per meal. These results suggest the potential of measuring individual feed intake of dairy cows in a cowshed using RGBD cameras and Deep Learning models that can be applied and tuned to different types of feed.
Traffic violations are deliberate deviations from safe driving rules associated with enhanced ris... more Traffic violations are deliberate deviations from safe driving rules associated with enhanced risks for crash involvement, impacted by traits and demographics. Violations tend to decrease with age, males and young drivers tend to make more violations. But some studies reported the opposite or no sex differences. We argue that part of this ambiguity can be attributed to gender role (Undifferentiated, Feminine, Masculine, and Androgynous). Previously, we showed that for a group of 527 adult drivers (mean age 29), gender role was a better predictor of violation tendency than sex. Now we extend this study by using a larger sample in three age categories (≤20, 21-54, and 55-65). We aim to examine whether gender role contributes to explaining violations. We distributed a web-based survey containing self-reports of traffic violations (DBQ; Reason et al., 1990), the Bem Sex-Role Inventory (BSRI; Bem, 1974), and demographics. In total we collected 1039 questionnaires, 485 females and 554 mal...
Companion of the 2020 ACM/IEEE International Conference on Human-Robot Interaction
Operators of military Unmanned Aerial Vehicles (UAVs) work in dynamic environments, where they mu... more Operators of military Unmanned Aerial Vehicles (UAVs) work in dynamic environments, where they must use shared command and control (C2) maps to orient, plan and perform their work. The map is overloaded with information that is irrelevant to their immediate operational mission. This clutter may harm their situation awareness (SA) and increase workload. An intelligent and dynamic filter algorithm has been developed to reduce the clutter by filtering information items on the map based on the environmental context. Implementing it raises questions regarding the update rate of the map filter. Two update rates were tested and their effect on UAV operators' workload and SA was examined empirically. Operators benefited from higher update rates in terms of SA and workload. This is an important step towards the development of the algorithm, which conceptualizes how intelligent algorithms can be used to improve human operators' interaction with autonomous systems.
Downward gazing is often observed when walking requires guidance. This gaze behavior is thought t... more Downward gazing is often observed when walking requires guidance. This gaze behavior is thought to promote walking stability through anticipatory stepping control. This study is part of an ongoing effort to investigate whether downward gazing also serves to enhance postural control, which can promote walking stability through a feedback/reactive mechanism. Since gaze behavior alone gives no indication as to what information is gathered and the functions it serves, we aimed to investigate the cognitive demands associated with downward gazing, as they are likely to differ between anticipatory and feedback use of visual input. To do so, we used a novel methodology to compromise walking stability in a manner that could not be resolved through modulation of stepping. Then, using interference methodology and neuroimaging, we tested for (1) interference related to dual tasking, and (2) changes in prefrontal activity. The novel methodology resulted in an increase in the time spent looking a...
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2016
We report the results of a study which aims to improve our understanding of how clinicians make s... more We report the results of a study which aims to improve our understanding of how clinicians make sense of medication and disease information (medical reconciliation), performed by clinicians in a major US hospital. A card sorting simulation experiment running on an Android tablet was utilized to record the steps taken by 130 clinicians to reconcile and better understand the clinical information they received about a simulated patient. Evaluating the order in which the clinicians processed the information shows that most clinicians sorted medical condition information before medication history. Clinicians use diverse strategies to arrange the information. This study allows us to expend our understanding of the cognitive task of medication reconciliation, adding to the knowledge that might assist in data presentation in future medical information software. Such an understanding has the potential to provide clinicians with better tools to capture and reconcile clinical information which...
Journal of NeuroEngineering and Rehabilitation, 2021
BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one fact... more BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one factor among the multiple components of the upper motor neuron syndrome that contributes to movement impairment. However, the specific contribution of spasticity is difficult to isolate and quantify. We propose a new method of quantification and evaluation of the impact of spasticity on the quality of movement following stroke.MethodsSpasticity was assessed using the Tonic Stretch Reflex Threshold (TSRT). TSRT was analyzed in relation to stochastic models of motion to quantify the deviation of the hemiparetic upper limb motion from the normal motion patterns during a reaching task. Specifically, we assessed the impact of spasticity in the elbow flexors on reaching motion patterns using two distinct measures of the ‘distance’ between pathological and normal movement, (a) the bidirectional Kullback–Liebler divergence (BKLD) and (b) Hellinger’s distance (HD). These measures differ in their sens...
This paper presents maturity classification algorithms developed for small datasets and methods t... more This paper presents maturity classification algorithms developed for small datasets and methods to deal with the highly variable and continuously changing agricultural environment. The algorithms were applied to the maturity classification of red and yellow sweet peppers, with data acquired from two different datasets, including 296 images. The maturity classification achieved 98.2 % and 97.3 % accuracy for classifying into two classes, between mature and immature classes of red and yellow peppers, respectively, and 89.5 % and 97.3 % accuracy for classifying into four maturity classes. The random forest algorithm is very robust and incurs a low computational cost, and therefore is recommended for the highly variable agricultural domain. An improvement of 28.65 % in classification accuracy was achieved by applying the methods developed for adapting to new datasets.
Background. Spasticity is common in patients with stroke, yet current quantification methods are ... more Background. Spasticity is common in patients with stroke, yet current quantification methods are insufficient for determining the relationship between spasticity and voluntary movement deficits. This is partly a result of the effects of spasticity on spatiotemporal characteristics of movement and the variability of voluntary movement. These can be captured by Gaussian mixture models (GMMs). Objectives. To determine the influence of spasticity on upper-limb voluntary motion, as assessed by the bidirectional Kullback-Liebler divergence (BKLD) between motion GMMs. Methods. A total of 16 individuals with subacute stroke and 13 healthy aged-equivalent controls reached to grasp 4 targets (near-center, contralateral, far-center, and ipsilateral). Two-dimensional GMMs (angle and time) were estimated for elbow extension motion. BKLD was computed for each individual and target, within the control group and between the control and stroke groups. Movement time, final elbow angle, average elbow ...
This paper focuses on maturity evaluation derived by a color camera for a sweet pepper robotic ha... more This paper focuses on maturity evaluation derived by a color camera for a sweet pepper robotic harvester. Different color and morphological features for sweet pepper maturity were evaluated. Side view and bottom view of sweet paper were analyzed and compared for their ability to classify into 4 maturity classes. The goal of this study was to differentiate between the two center classes which are difficult to separate. Statistical analysis of 13 different features in reliance to the maturity classification and the views indicated the best features for classification. The results show that the features that can be used for classification between the two central classes from both bottom and side views are: Hue range, Equal2Real – the ratio between the equivalent equal sized circle perimeter to the shape perimeter and Area2Peri – the ratio between the area to the perimeter.
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2015
In military operations, most of the communication is handled by audio and visual devices. Less co... more In military operations, most of the communication is handled by audio and visual devices. Less common is the use of tactile interfaces. Experiments in the dome simulator provide a controlled way to examine soldiers’ display devices within their context of use. Participants are immersed in a virtual hostile environment and utilize a display device conveying video feed from unmanned systems and alerts while having also to attend to their immediate environment. This type of situation allows examining higher workloads and task demands and it is in such conditions that it was hypothesized that the addition of tactile alerts will be beneficial. Results of an experiment conducted on 22 reserve soldier participants reveal that there are advantages to the use of the combined visual+tactile alert interface. However, they also raise concerns as to the ability of soldiers to attend to a display device and to their immediate environment at the same time and call for further research on the utili...
Transportation Research Part F: Traffic Psychology and Behaviour, 2016
Abstract Background Traffic safety is often expressed as the ‘inverse of accidents’. However, it ... more Abstract Background Traffic safety is often expressed as the ‘inverse of accidents’. However, it is more than the mere absence of accidents. Past studies often looked for associations between accidents and self-reports like the Driver Behaviour Questionnaire (DBQ; Reason, Manstead, Stradling, Baxter, & Campbell, 1990). The focus in this study changed from counting accidents to quantifying unsafe acts as violations. The objective was to show that drivers' specific violations can be traced to personal characteristics such as sensation seeking (SSS-V; Zuckerman, 1994), gender role (BSRI; Bem sex role inventory, Bem, 1974), demographics, and driving exposure. Method A web-based questionnaire was distributed, integrating several known questionnaires. Five hundred and twenty-seven questionnaires were completed and analyzed. Results Sensation seeking, gender role, experience, and age predicted respondents’ score on the DBQ, as well as the interaction of sensation seeking with gender and gender role. Gender role was a more valid predictor of driver behavior than gender. Conclusions The effect of gender role on drivers’ self-reported violation tendency is the most interesting and the most intriguing finding of this survey and indicates the need to further examine gender role affects in driving.
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2017
Children are a high-risk group for motor vehicle injuries, and characterized also by extensive us... more Children are a high-risk group for motor vehicle injuries, and characterized also by extensive use of mobile phones. We investigated the influence of playing a mobile phone game on crossing behavior of children relative to adults. Our hypotheses were that: a) game use will affect pedestrian’s crossing behavior for all age groups; and b) increase in the complexity of the game will cause greater impact on crossing behavior. Twenty-seven children and twenty-one adults (mean=25.3, sd=1.5) participated. Children were divided into two ages; nine children aged 9-10 (mean=9.2, sd=0.4), and eighteen children aged 11-13 (mean=11.9, sd=0.6). The experiment took place in our Dome pedestrian simulator. Twelve simulated street-crossing scenarios, each lasting for 60-90 seconds; six in each environmental load (high/low clutter). Scenarios were presented from a pedestrian point of view, as if they were standing on the curb on one side of the road facing to the other side of a two lane street with t...
Maturity evaluation is an important feature for selective robotic harvesting. This paper focuses ... more Maturity evaluation is an important feature for selective robotic harvesting. This paper focuses on maturity evaluationderived by a color camera for a sweet pepper robotic harvester. Fruit visibili ...
Background Advanced age and brain damage have been reported to increase the propensity to gaze do... more Background Advanced age and brain damage have been reported to increase the propensity to gaze down while walking, a behavior that is thought to enhance stability through anticipatory stepping control. Recently, downward gazing (DWG) has been shown to enhance postural steadiness in healthy adults, suggesting that it can also support stability through a feedback control mechanism. These results have been speculated to be the consequence of the altered visual flow when gazing down. The main objective of this cross-sectional, exploratory study was to investigate whether DWG also enhances postural control in older adults and stroke survivors, and whether such effect is altered with aging and brain damage. Methods Posturography of older adults and stroke survivors, performing a total of 500 trials, was tested under varying gaze conditions and compared with a cohort of healthy young adults (375 trials). To test the involvement of the visual system we performed spectral analysis and compared the changes in the relative power between gaze conditions. Results Reduction in postural sway was observed when participants gazed down 1 and 3 meters ahead whereas DWG towards the toes decreased steadiness. These effects were unmodulated by age but were modulated by stroke. The relative power in the spectral band associated with visual feedback was significantly reduced when visual input was unavailable (eyes-closed condition) but was unaffected by the different DWG conditions. Conclusions Like young adults, older adults and stroke survivors better control their postural sway when gazing down a few steps ahead, but extreme DWG can impair this ability, especially in people with stroke.
This study explored pedestrians’ understanding of Fully Autonomous Vehicles (FAVs) intention to s... more This study explored pedestrians’ understanding of Fully Autonomous Vehicles (FAVs) intention to stop and what influences pedestrians’ decision to cross the road over time, i.e., learnability. Twenty participants saw fixed simulated urban road crossing scenes with a single FAV on the road as if they were pedestrians intending to cross. Scenes differed from one another in the FAV’s, distance from the crossing place, its physical size, and external Human-Machine Interfaces (e-HMI) message by background color (red/green), message type (status/advice), and presentation modality (text/symbol). Eye-tracking data and decision measurements were collected. Results revealed that pedestrians tend to look at the e-HMI before making their decision. However, they did not necessarily decide according to the e-HMIs’ color or message type. Moreover, when they complied with the e-HMI proposition, they tended to hesitate before making the decision. Overall, a learning effect over time was observed in a...
To explore cognitive strategies clinicians apply while performing a medication reconciliation tas... more To explore cognitive strategies clinicians apply while performing a medication reconciliation task, handling incomplete and conflicting information. Background: Medication reconciliation is a method clinicians apply to find and resolve inconsistencies in patients' medications and medical conditions lists. The cognitive strategies clinicians use during reconciliation are unclear. Controlled lab experiments can explore how clinicians make sense of uncertain, missing, or conflicting information and therefore support the development of a human performance model. We hypothesize that clinicians apply varied cognitive strategies to handle this task and that profession and experience affect these strategies. Method: 130 clinicians participated in a tablet-based experiment conducted in a large American teaching hospital. They were asked to simulate medication reconciliation using a card sorting task (CaST) to organize medication and medical condition lists of a specific clinical case. Later on, they were presented with new information and were asked to add it to their arrangements. We quantitatively and qualitatively analyzed the ways clinicians arranged patient information. Results: Four distinct cognitive strategies were identified ("Conditions first": n = 76 clinicians, "Medications first": n = 7, "Crossover": n = 17, and "Alternating": n = 10). The strategy clinicians applied was affected by their experience (p = .02) but not by their profession. At the appearance of new information, clinicians moved medication cards more frequently (75.2 movements vs. 49.6 movements, p < .001), suggesting that they match medications to medical conditions. Conclusion: Clinicians apply various cognitive strategies while reconciling medications and medical conditions. Application: Clinical information systems should support multiple cognitive strategies, allowing flexibility in organizing information.
Data on individual feed intake of dairy cows, an important variable for farm management, are curr... more Data on individual feed intake of dairy cows, an important variable for farm management, are currently unavailable in commercial dairies. A real-time machine vision system including models that are able to adapt to multiple types of feed was developed to predict individual feed intake of dairy cows. Using a Red-Green-Blue-Depth (RGBD) camera, images of feed piles of two different feed types (lactating cows' feed and heifers' feed) were acquired in a research dairy farm, for a range of feed weights under varied configurations and illuminations. Several models were developed to predict individual feed intake: two Transfer Learning (TL) models based on Convolutional Neural Networks (CNNs), one CNN model trained on both feed types, and one Multilayer Perceptron and Convolutional Neural Network model trained on both feed types, along with categorical data. We also implemented a statistical method to compare these four models using a Linear Mixed Model and a Generalised Linear Mixed Model, showing that all models are significantly different. The TL models performed best and were trained on both feeds with TL methods. These models achieved Mean Absolute Errors (MAEs) of 0.12 and 0.13 kg per meal with RMSE of 0.18 and 0.17 kg per meal for the two different feeds, when tested on varied data collected manually in a cowshed. Testing the model with actual cows' meals data automatically collected by the system in the cowshed resulted in a MAE of 0.14 kg per meal and RMSE of 0.19 kg per meal. These results suggest the potential of measuring individual feed intake of dairy cows in a cowshed using RGBD cameras and Deep Learning models that can be applied and tuned to different types of feed.
Traffic violations are deliberate deviations from safe driving rules associated with enhanced ris... more Traffic violations are deliberate deviations from safe driving rules associated with enhanced risks for crash involvement, impacted by traits and demographics. Violations tend to decrease with age, males and young drivers tend to make more violations. But some studies reported the opposite or no sex differences. We argue that part of this ambiguity can be attributed to gender role (Undifferentiated, Feminine, Masculine, and Androgynous). Previously, we showed that for a group of 527 adult drivers (mean age 29), gender role was a better predictor of violation tendency than sex. Now we extend this study by using a larger sample in three age categories (≤20, 21-54, and 55-65). We aim to examine whether gender role contributes to explaining violations. We distributed a web-based survey containing self-reports of traffic violations (DBQ; Reason et al., 1990), the Bem Sex-Role Inventory (BSRI; Bem, 1974), and demographics. In total we collected 1039 questionnaires, 485 females and 554 mal...
Companion of the 2020 ACM/IEEE International Conference on Human-Robot Interaction
Operators of military Unmanned Aerial Vehicles (UAVs) work in dynamic environments, where they mu... more Operators of military Unmanned Aerial Vehicles (UAVs) work in dynamic environments, where they must use shared command and control (C2) maps to orient, plan and perform their work. The map is overloaded with information that is irrelevant to their immediate operational mission. This clutter may harm their situation awareness (SA) and increase workload. An intelligent and dynamic filter algorithm has been developed to reduce the clutter by filtering information items on the map based on the environmental context. Implementing it raises questions regarding the update rate of the map filter. Two update rates were tested and their effect on UAV operators' workload and SA was examined empirically. Operators benefited from higher update rates in terms of SA and workload. This is an important step towards the development of the algorithm, which conceptualizes how intelligent algorithms can be used to improve human operators' interaction with autonomous systems.
Downward gazing is often observed when walking requires guidance. This gaze behavior is thought t... more Downward gazing is often observed when walking requires guidance. This gaze behavior is thought to promote walking stability through anticipatory stepping control. This study is part of an ongoing effort to investigate whether downward gazing also serves to enhance postural control, which can promote walking stability through a feedback/reactive mechanism. Since gaze behavior alone gives no indication as to what information is gathered and the functions it serves, we aimed to investigate the cognitive demands associated with downward gazing, as they are likely to differ between anticipatory and feedback use of visual input. To do so, we used a novel methodology to compromise walking stability in a manner that could not be resolved through modulation of stepping. Then, using interference methodology and neuroimaging, we tested for (1) interference related to dual tasking, and (2) changes in prefrontal activity. The novel methodology resulted in an increase in the time spent looking a...
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2016
We report the results of a study which aims to improve our understanding of how clinicians make s... more We report the results of a study which aims to improve our understanding of how clinicians make sense of medication and disease information (medical reconciliation), performed by clinicians in a major US hospital. A card sorting simulation experiment running on an Android tablet was utilized to record the steps taken by 130 clinicians to reconcile and better understand the clinical information they received about a simulated patient. Evaluating the order in which the clinicians processed the information shows that most clinicians sorted medical condition information before medication history. Clinicians use diverse strategies to arrange the information. This study allows us to expend our understanding of the cognitive task of medication reconciliation, adding to the knowledge that might assist in data presentation in future medical information software. Such an understanding has the potential to provide clinicians with better tools to capture and reconcile clinical information which...
Journal of NeuroEngineering and Rehabilitation, 2021
BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one fact... more BackgroundHemiparesis following stroke is often accompanied by spasticity. Spasticity is one factor among the multiple components of the upper motor neuron syndrome that contributes to movement impairment. However, the specific contribution of spasticity is difficult to isolate and quantify. We propose a new method of quantification and evaluation of the impact of spasticity on the quality of movement following stroke.MethodsSpasticity was assessed using the Tonic Stretch Reflex Threshold (TSRT). TSRT was analyzed in relation to stochastic models of motion to quantify the deviation of the hemiparetic upper limb motion from the normal motion patterns during a reaching task. Specifically, we assessed the impact of spasticity in the elbow flexors on reaching motion patterns using two distinct measures of the ‘distance’ between pathological and normal movement, (a) the bidirectional Kullback–Liebler divergence (BKLD) and (b) Hellinger’s distance (HD). These measures differ in their sens...
This paper presents maturity classification algorithms developed for small datasets and methods t... more This paper presents maturity classification algorithms developed for small datasets and methods to deal with the highly variable and continuously changing agricultural environment. The algorithms were applied to the maturity classification of red and yellow sweet peppers, with data acquired from two different datasets, including 296 images. The maturity classification achieved 98.2 % and 97.3 % accuracy for classifying into two classes, between mature and immature classes of red and yellow peppers, respectively, and 89.5 % and 97.3 % accuracy for classifying into four maturity classes. The random forest algorithm is very robust and incurs a low computational cost, and therefore is recommended for the highly variable agricultural domain. An improvement of 28.65 % in classification accuracy was achieved by applying the methods developed for adapting to new datasets.
Background. Spasticity is common in patients with stroke, yet current quantification methods are ... more Background. Spasticity is common in patients with stroke, yet current quantification methods are insufficient for determining the relationship between spasticity and voluntary movement deficits. This is partly a result of the effects of spasticity on spatiotemporal characteristics of movement and the variability of voluntary movement. These can be captured by Gaussian mixture models (GMMs). Objectives. To determine the influence of spasticity on upper-limb voluntary motion, as assessed by the bidirectional Kullback-Liebler divergence (BKLD) between motion GMMs. Methods. A total of 16 individuals with subacute stroke and 13 healthy aged-equivalent controls reached to grasp 4 targets (near-center, contralateral, far-center, and ipsilateral). Two-dimensional GMMs (angle and time) were estimated for elbow extension motion. BKLD was computed for each individual and target, within the control group and between the control and stroke groups. Movement time, final elbow angle, average elbow ...
This paper focuses on maturity evaluation derived by a color camera for a sweet pepper robotic ha... more This paper focuses on maturity evaluation derived by a color camera for a sweet pepper robotic harvester. Different color and morphological features for sweet pepper maturity were evaluated. Side view and bottom view of sweet paper were analyzed and compared for their ability to classify into 4 maturity classes. The goal of this study was to differentiate between the two center classes which are difficult to separate. Statistical analysis of 13 different features in reliance to the maturity classification and the views indicated the best features for classification. The results show that the features that can be used for classification between the two central classes from both bottom and side views are: Hue range, Equal2Real – the ratio between the equivalent equal sized circle perimeter to the shape perimeter and Area2Peri – the ratio between the area to the perimeter.
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2015
In military operations, most of the communication is handled by audio and visual devices. Less co... more In military operations, most of the communication is handled by audio and visual devices. Less common is the use of tactile interfaces. Experiments in the dome simulator provide a controlled way to examine soldiers’ display devices within their context of use. Participants are immersed in a virtual hostile environment and utilize a display device conveying video feed from unmanned systems and alerts while having also to attend to their immediate environment. This type of situation allows examining higher workloads and task demands and it is in such conditions that it was hypothesized that the addition of tactile alerts will be beneficial. Results of an experiment conducted on 22 reserve soldier participants reveal that there are advantages to the use of the combined visual+tactile alert interface. However, they also raise concerns as to the ability of soldiers to attend to a display device and to their immediate environment at the same time and call for further research on the utili...
Transportation Research Part F: Traffic Psychology and Behaviour, 2016
Abstract Background Traffic safety is often expressed as the ‘inverse of accidents’. However, it ... more Abstract Background Traffic safety is often expressed as the ‘inverse of accidents’. However, it is more than the mere absence of accidents. Past studies often looked for associations between accidents and self-reports like the Driver Behaviour Questionnaire (DBQ; Reason, Manstead, Stradling, Baxter, & Campbell, 1990). The focus in this study changed from counting accidents to quantifying unsafe acts as violations. The objective was to show that drivers' specific violations can be traced to personal characteristics such as sensation seeking (SSS-V; Zuckerman, 1994), gender role (BSRI; Bem sex role inventory, Bem, 1974), demographics, and driving exposure. Method A web-based questionnaire was distributed, integrating several known questionnaires. Five hundred and twenty-seven questionnaires were completed and analyzed. Results Sensation seeking, gender role, experience, and age predicted respondents’ score on the DBQ, as well as the interaction of sensation seeking with gender and gender role. Gender role was a more valid predictor of driver behavior than gender. Conclusions The effect of gender role on drivers’ self-reported violation tendency is the most interesting and the most intriguing finding of this survey and indicates the need to further examine gender role affects in driving.
Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2017
Children are a high-risk group for motor vehicle injuries, and characterized also by extensive us... more Children are a high-risk group for motor vehicle injuries, and characterized also by extensive use of mobile phones. We investigated the influence of playing a mobile phone game on crossing behavior of children relative to adults. Our hypotheses were that: a) game use will affect pedestrian’s crossing behavior for all age groups; and b) increase in the complexity of the game will cause greater impact on crossing behavior. Twenty-seven children and twenty-one adults (mean=25.3, sd=1.5) participated. Children were divided into two ages; nine children aged 9-10 (mean=9.2, sd=0.4), and eighteen children aged 11-13 (mean=11.9, sd=0.6). The experiment took place in our Dome pedestrian simulator. Twelve simulated street-crossing scenarios, each lasting for 60-90 seconds; six in each environmental load (high/low clutter). Scenarios were presented from a pedestrian point of view, as if they were standing on the curb on one side of the road facing to the other side of a two lane street with t...
Maturity evaluation is an important feature for selective robotic harvesting. This paper focuses ... more Maturity evaluation is an important feature for selective robotic harvesting. This paper focuses on maturity evaluationderived by a color camera for a sweet pepper robotic harvester. Fruit visibili ...
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Papers by Yisrael Parmet