Assembly Task Performance Research Articles

Transcranial direct current stimulation to the left dorsolateral prefrontal cortex enhances early dexterity skills with the left non-dominant hand: a randomized controlled trial

BackgroundThe left dorsolateral prefrontal cortex (DLPFC) is involved in early-phase manual dexterity skill acquisition when cognitive control processes, such as integration and complexity demands, are required. However, the effectiveness of left DLPFC transcranial direct current stimulation (tDCS) on early-phase motor learning and whether its effectiveness depends on the cognitive demand of the target task are unclear. This study aimed to investigate whether tDCS over the left DLPFC improves non-dominant hand dexterity performance and determine if its efficacy depends on the cognitive demand of the target task.MethodsIn this randomized, double-blind, sham-controlled trial, 70 healthy, right-handed, young adult participants were recruited. They were randomly allocated to the active tDCS (2 mA for 20 min) or sham groups and repeatedly performed the Purdue Pegboard Test (PPT) left-handed peg task and left-handed assembly task three times: pre-tDCS, during tDCS, and post tDCS.ResultsThe final sample comprised 66 healthy young adults (mean age, 22.73 ± 1.57 years). There were significant interactions between group and time in both PPT tasks, indicating significantly higher performance of those in the active tDCS group than those in the sham group post tDCS (p < 0.001). Moreover, a greater benefit was observed in the left-handed assembly task performance than in the peg task performance (p < 0.001). No significant correlation between baseline performance and benefits from tDCS was observed in either task.ConclusionsThese results demonstrated that prefrontal tDCS significantly improved early-phase manual dexterity skill acquisition, and its benefits were greater for the task with high cognitive demands. These findings contribute to a deeper understanding of the underlying neurophysiological mechanisms of the left DLPFC in the modulation of early-phase dexterity skill acquisition.Trial registration: This study was registered in the University Hospital Medical Information Network Clinical Trial Registry in Japan (UMIN000046868), Registered February 8, 2022 https://center6.umin.ac.jp/cgi-open-bin/ctr_e/ctr_view.cgi?recptno=R000053467

Effect of Virtual Reality-Based Training on Complex Industrial Assembly Task Performance

Effect of Virtual Reality-Based Training on Complex Industrial Assembly Task Performance

Overloaded and at Work: Investigating the Effect of Cognitive Workload on Assembly Task Performance.

ObjectiveThis study investigates the effect of cognitive overload on assembly task performance and muscle activity.BackgroundUnderstanding an operator’s cognitive workload is an important component in assessing human–machine interaction. However, little evidence is available on the effect that cognitive overload has on task performance and muscle activity when completing manufacturing tasks.MethodTwenty-two volunteers completed an assembly task while performing a secondary cognitive task with increasing levels of demand (n-back). Performance in the assembly task (completion times, accuracy), muscle activity recorded as integrated electromyography (EMG), and self-reported workload were measured.ResultsResults show that the increasing cognitive demand imposed by the n-back task resulted in impaired assembly task performance, overall greater muscle activity, and higher self-reported workload.Relative to the control condition, performing the 2-back task resulted in longer assembly task completion times (+10 s on average) and greater integrated EMG for flexor carpi ulnaris, triceps brachii, biceps brachii, anterior deltoid, and pectoralis major.ConclusionThis study demonstrates that working under high cognitive load not only results in greater muscle activity, but also affects assembly task completion times, which may have a direct effect on manufacturing cycle times.ApplicationResults are applicable to the assessment of the effects of high cognitive workload in manufacturing.

Piecing It Together: The Effect of Background Music on Children's Puzzle Assembly.

This study explored the effects of background music on cognitive (puzzle assembly) task performance in young children. Participants were 87 primarily European-American children (38 boys, 49 girls; mean age = 4.77 years) enrolled in early childhood classes in the northeastern United States. Children were given one minute to complete a 12-piece puzzle task in one of three background music conditions: music with lyrics, music without lyrics, and no music. The music selection was "You're Welcome" from the Disney movie "Moana." Results revealed that children who heard the music without lyrics completed more puzzle pieces than children in either the music with lyrics or no music condition. Background music without distracting lyrics may be beneficial and superior to background music with lyrics for young children's cognitive performance even when they are engaged independently in a nonverbal task.

A modified perturbation/correlation method for force-guided assembly

The present study proposes the Modified perturbation/correlation method (MPCM) as a way of performing assembly tasks and an algorithm by which assembly task can be performed automatically, without human intervention. The MPCM is a method where position/ orientation perturbation is generated when the female connector and the male connector are connected and the correlation value of the resulting reaction force/moment is used to calculate and to correct the position and orientation errors between the connectors. The successful performance of assembly task within a limited error range can be confirmed by applying the MPCM to DRC-HUBO. When there are errors between the connector, the correlation value can be confirmed to converge to 0 as errors are corrected even though it takes on certain directionality.

A Comparison of Covert and Videotape Modeling Strategies for Training Complex Mechanical Assembly Tasks

Experimentation was conducted comparing videotape self-modeling and videotape peer/other modeling to self-directed mental rehearsal (a covert modeling procedure) and a no-training (physical practice) control condition in training a mechanical device assembly task. Eighty male and female college students were introduced to the assembly task in a timed pretest trial and then videotaped performing the assembly task in a second trial. Over the next 4 days, subjects were randomly assigned to training conditions and repeatedly trained and tested in the mechanical device assembly task. The effects of training methods upon assembly times, self-efficacy expectations regarding assembly task performance, and subjective impressions of the nature and usefulness of training were examined. Superior assembly performance over initial training and at 4 months post-training follow-up was observed for the self-directed mental rehearsal training condition and discussed.

Evaluation of Auditory and Visual Feedback on Task Performance in a Virtual Assembly Environment

This paper presents the creation of an assembly simulation environment with multisensory feedback (auditory and visual), and the evaluation of the effects of auditory and visual feedback on the task performance in the context of assembly simulation in a virtual environment (VE). This VE experimental system platform brings together complex technologies such as constraint-based assembly simulation, optical motion tracking technology, and real time 3D sound generation technology around a virtual reality workbench and a common software platform. A peg-in-a-hole and a Sener electronic box assembly task have been used as the task cases to conduct the human factor experiment, using sixteen participants. Both objective performance data (i.e., task completion time, TCT; and human performance error rate, HPER) and subjective opinions (i.e., questionnaires) on the utilization of auditory and visual feedback in a virtual assembly environment (VAE) have been gathered from the experiment. Results showed that the introduction of auditory and/or visual feedback into VAE did improve the assembly task performance. They also indicated that integrated feedback (auditory plus visual) offered better assembly task performance than either feedback used in isolation. Most participants preferred integrated feedback to either individual feedback (auditory or visual) or no feedback. The participants' comments demonstrated that nonrealistic or inappropriate feedback had a negative effect on the task performance, and easily made them frustrated.

Identifying the task variables that influence perceived object assembly complexity

There is a general lack of understanding as to what issues affect assembly task performance when using diagrammatic instructions because few of the task variables contributing to assembly complexity have been identified. Using a task analysis of a range of self-assembly products, seven task variables hypothesized to predict assembly complexity were identified and studied in the instruction comprehension phase of assembly. Experiment 1 took nine real world assembly instructions and described each in terms of the seven task variables. Seventy-two participants gave a subjective rating of assembly difficulty for each assembly, showing a clear relationship between the task variables and perceived assembly difficulty. As real world assemblies provide little control a second experiment used an orthogonal design to systematically vary the values of each of the assembly task variables in 16 abstract assemblies. Forty-two participants compared the 16 assembly instructions to a final assembly. There was a clear relationship between the task variables and the time taken to view the instructions. Further, it was found that it is possible to predict the complexity of assembly tasks based upon the levels of the task variables identified. The task variables identified are a significant step towards identifying the factors that influence assembly complexity, together with providing progress towards a tool for predicting assembly complexity.

Matching Instructional Media with Instructional Demands

Video instruction is an effective support for audio instruction of visuospatial tasks; but how is effectiveness of this type of instruction moderated? We investigated the effects of age-related cognitive changes, audio versus audio-plus-video instructions, differential working memory instruction demands, and differential task difficulty on assembly task performance. Forty-eight young adults and 48 older adults completed an assembly task where accuracy, use of additional time, repetition of steps, and subjective mental workload were measured. Results indicated that participants receiving audio plus video instruction benefited most as task difficulty increased. Older adults performed more poorly compared to young adults; however, the findings indicate that video-based instruction was beneficial for both young and older adults for this class of task. Results are discussed from a training perspective in general and as they relate to telemedicine specifically. Guidelines for applying the correct instructional media as a function of the instructional demands are discussed.

The development and evaluation of an ergonomic glove

The primary intent of this study was to determine if a hand glove could be designed on a criterion of selective protection. Force distribution patterns on the palmar side of hand were obtained from various studies to develop zones of hand that needed protection. A new design for gloves was developed based on the principle of selective protection, where protective material is introduced in varying levels over different parts of the glove, in order to provide protection where it is most needed, and at the same time preserve the desirable dexterity and strength capabilities of the barehand, optimizing the trade-off between protection and performance. Two pairs of prototype gloves incorporating different levels of protection were fabricated and tested using a battery of performance tests and an algometer test for pressure sensitivity. The test battery comprising four dexterity tasks and a maximal voluntary grip strength task was used to assess a number of glove conditions, including the two prototype gloves developed. The results indicate that the performance of the prototype gloves are comparable, and that the performance times for the double glove and the two prototype gloves tested were not significantly different. For the grip strength, the two prototype gloves were better than the double glove. The assembly task performance for the prototype II (laminar glove) was significantly lower than that of the other glove types tested. It appears that gloves of variable thickness can be developed to afford adequate protection at zones of most need. Glove manufacturers are recommended to use an ergonomic approach in the design of gloves. Such an approach, besides protecting the safety objective of gloves, could enhance productivity considerably.

Ergonomic Glove: Design and Evaluation

A new design for gloves was developed based on the principle of selective protection, where protective material is introduced in varying levels over different parts of the glove, in order to provide protection where it is most needed, and at the same time preserve the desirable dexterity and strength capabilities of the barehand, optimizing the trade-off between protection and performance. The pattern for selective protection was arrived at based on existing research, and two pairs of gloves incorporating different levels of protection have been prototyped and are currently being tested using a battery of performance tests and an Algometer test for pressure sensitivity. A battery of tests was developed to evaluate a new glove design which used the principle of selective levels of protection over different parts of the hand, in order to maximize protection, and minimize loss of dexterity. The test battery comprised of four dexterity tasks and a maximal voluntary grip strength task. The battery assessed the performance of 5 hand conditions, barehand, single glove (one layer), double glove (two layers), and two prototype gloves, one with one layer of protection (contour glove) and the other with four layers of protection over selected parts of the hand (laminar glove). The evaluation compared the performance of the prototype gloves developed with respect to the performance with the double layer glove and the single layer glove. The results indicated that the performance of the prototype gloves was comparable, and that the performance times for the double glove and the two prototype gloves tested were not significantly different. For the test of grip strength, the two prototype gloves tested enabled better performance than the double glove. The assembly task performance for the prototype II (laminar glove) was significantly lower than that of the other glove types tested

Assembly task performance and ambient temperature: A reliability model

The performance of certain hand activities is influenced by reduced ambient temperatures. Seventy trained subjects completed an assembly task at air temperatures of 1·7°C, 12·8°C and 23·9°C, and their completion times were recorded. Based on the experimental results, an empirical relationship between the cumulative probability of completion, the air temperature, and the performance times was developed. The empirical distribution is equivalent to the reliability function of the assembly task. Results indicated no difference between performance at 12·8°C and 23·9°C but a reduction in performance at 1·7°C. The model was compared with experimental trials of a similar task.

The Effects of Warning Message Highlighting on Novel Assembly Task Performance

A review of examples and specifications relating to critical operating procedures revealed considerable variation in recommended standards for highlighting warning messages. An experiment was therefore conducted to examine the effectiveness of various methods of highlighting warning messages contained in the instructions for a novel assembly task. Findings indicated that the presence of warning messages shortened task completion times and reduced error rates between the experimental and control groups.

The Effects of Alcohol on Performance of a Production Assembly Task

Phase I of this study investigated the effects of a trace level of alcohol (1·3 mM) and a very low level of blood alcohol (3·7 mM) on the manual assembly of a common water tap. The productivity measure used was the time required to assemble six taps. The quality of work measure was the number of assembly sequence and improper assembly errors. Six subjects participated in the repeated measures design. Ordered treatment effects were significant at p<0·05 using the Page nonparametric test for the overall elapsed time scores and for twist, grasp and return micromotion work elements. There was a 2·9% increase in overall elapsed time with a mean blood alcohol content of 3·7 mM. Quality of work degraded with increased blood alcohol content, p<0·05. Phase II used the same experimental design to investigate effects at 6·54 mM and 14·8 mM average blood alcohol content. The Page tests for overall assembly time and for the twist therblig were both significant at p<0·05. The increase in overall assembly time for 6·54 ...

Cognitive efficiency of divers working in cold water.

The cognitive efficiency of 14 divers was studied during 1-hour exposure to water of 40°F (4.4°C) and 78°F (25.6°C). Reasoning ability was tested using a sentence comprehension task presented at the beginning and end of each test session. Vigilance was tested by requiring subjects to detect the onset of a faint peripheral light during the performance of a two-man pipe assembly task. Memory was tested by requiring subjects to learn a number of “facts” during the dive, with retention tested by recall and recognition on land, after a 40-min delay. Despite a mean drop in rectal temperature of 1.3°F (0.72°C), neither reasoning nor vigilance was impaired. Memory performance did deteriorate, though it is suggested that this may reflect a peripheral context-dependent memory effect. It is concluded that a well-motivated subject may be cognitively unimpaired despite a marked drop in deep body temperature.