An imperceptible barcode can reduce the muscle activity required to scan common consumer packaged goods

While the Universal Product Code (UPC) has remained unchanged since its implementation in the 1970s, new technology and consumer package good layouts have started to change the UPC layout. The purpose of this study was to compare how upper extremity muscle activity was altered when scanning consumer packaged goods enhanced with an imperceptible barcode or a multi-sided UPC layout. Seventeen experienced cashiers participated in this study. Electromyography of four bilateral upper extremity muscles was recorded when scanning individual consumer packaged goods and a mock grocery cart. Scanning time and integrated electromyography were compared between the packages enhanced with an imperceptible barcode or the multi-sided barcodes versus the traditional barcodes. Participants were more efficient when scanning packages with the altered barcodes compared to the traditional barcode. Scanning the individual consumer packaged goods resulted in lower peak muscle activity for the shoulder muscles and elbow flexors when using packages enhanced with the imperceptible barcode. When extrapolated over a 4-h shift, the packages enhanced with the imperceptible barcode lowered upper extremity cumulative muscle activity measured muscles; however, the multi-sided layout only demonstrated a reduced muscular activity for the trapezius and left forearm. Future work must continue to assess grocery scanning practices, training, and other alternative scanning practices, such as hand scanners and self-checkout stands.     

Design and sizing of ergonomic handles for hand tools

In this paper, handles for two commonly used hand tools, the chisel and the off-set pliers, are designed using ergonomic principles. These were sized for both males and females falling in the 5th percentile, 50th percentile and 95th percentile groupings. The stresses developed in the ergonomically designed chisel handle while in use were analysed to verify the validity of the design. This chisel handle was then manufactured, and preliminary evaluation using electromyography was conducted. In these tests, the stresses exerted on the flexor and extensor muscles of the arm were measured and compared with those obtained during the use of a conventional handle. Under similar working conditions, results clearly showed that the ergonomically designed handle allows higher working efficiency than existing handles.     

Computer tutors can reduce student errors and promote solution efficiency for complex engineering problems

An ability to solve complex problems, for which a variety of solution paths are possible, is an important goal in engineering education. While feedback is critical to learning, hand grading of homework rarely provides effective, timely feedback on attempts to solve complex problems. Such feedback is also unfeasible in distance education contexts. A technology, based on the approach of cognitive tutors, is presented as a generally applicable method of providing automated feedback on complex problem solving, with truss problems studied in engineering as an example. The tutor maintains a cognitive model of problem solving for this class of problems, and associates various solution steps with distinct skills or knowledge components. One can determine whether students learn individual skills by measuring the error rate as a function of practice. Prior work has shown that for many skills the error rate indeed decreases with practice. New insight into the tutor׳s effectiveness, pertaining to the efficiency of student solution paths, is presented in this paper. While no explicit feedback is given regarding solution efficiency, it is found that students using the tutor become more efficient with practice. Furthermore, more efficient paths are found to be associated with making fewer errors.     

Leveraging active learning to reduce human effort in the generation of ground-truth for entity resolution

Several methods of entity resolution (ER) have been developed in academia and industry over the years, with the intention to identify duplicate entities (eg, records) in datasets. To evaluate the efficacy of such methods, it is necessary to compare their results with a ground-truth, which consists of a document containing all known duplicate record pairs in a dataset. In general, the generation of ground-truths for real datasets is performed manually from the inspection of all combinations of pairs of records in a dataset. This is subject to error and presents quadratic complexity, with respect to the size(s) of the dataset(s), requiring a long time to be performed. In this context, some works present (semi)automatic approaches for the generation of ground-truths for the ER task. However, such approaches are either not applicable to several domains or still present a considerable manual effort. In this work, we propose GTGenERAL, a semiautomatic approach that combines results from multiple algorithms of ER together with active learning to generate accurate ground-truths employing reduced manual effort. Experiments using real datasets show that, with great manual effort reduction, GTGenERAL is able to generate ground-truths close to those generated by the state-of-the-art approach.     

Second generation pleated pneumatic artificial muscle and its robotic applications

This paper reports on the second generation of the pleated pneumatic artificial muscle (PPAM) which has been developed to extend the lifespan of its first prototype. This type of artificial muscle was developed to overcome dry friction and material deformation which is present in the widely used McKibben muscle. The essence of the PPAM is its pleated membrane structure which enables the muscle to work at low pressures and at large contractions. There is growing interest in this kind of actuation for robotics applications due to its high power to weight ratio and adaptable compliance, especially for legged locomotion and robot applications in direct contact with a human. This paper describes the design of the second-generation PPAM, for which specifically the membrane layout has been changed. In terms of this new layout the mathematical model, developed for the first prototype, has been reformulated. This paper gives an elaborate discussion on this mathematical model that represents the force generation and enclosed muscle volume. Static load tests on some real muscles, which have been carried out in order to validate the mathematical model, are then discussed. Furthermore, two robotic applications are given which successfully use these pneumatic artificial muscles. One is the biped Lucy and the another one is a manipulator application which works in direct contact with an operator.     

Effects of carrying methods and box handles on two-person team carrying capacity for females

This study used a psychophysical approach to examine the effects of carrying methods and the presence or absence of box handles on the maximum acceptable weight carried and resulting responses (heart rate and rating of perceived exertion) in a two-person carrying task. After training, 16 female subjects performed a two-person carrying task at knuckle height for an 8-h work period. Each subject performed 4 different carrying combinations two times. The independent variables were carrying methods (parallel and tandem walking) and box handles (with and without handles). For comparison with two-person carrying, the subjects also performed one-person carrying. The results showed that the maximum acceptable weight carried (MAWC), heart rate (HR), and rating of perceived exertion (RPE) were significantly affected by the presence of box handles. However, the subjects' MAWC, HR, and RPE values were not significantly influenced by the carrying methods. The test-retest reliability of the psychophysical approach was 0.945. The carrying efficiency of two-person carrying was 96.2% of the one-person carrying method. In general, the use of box with handles allows the subjects to carry a higher MAWC (with lower HR and RPE) compared to carrying boxes without handles.     

Acceleration and torque redistribution for a dual-manipulator system

Recent research has considered robotic machining as an alternative to traditional computer numerical control machining, particularly for prototyping applications. However, unlike traditional machine tools, robots are subject to relatively larger dynamic disturbances and operate closer to their torque limits. These factors, combined with inaccurate manipulator and machining process models, can cause joint actuator saturation during operation. This paper presents a trajectory planner that will reduce torques that are near saturation by generating trajectories with a weighted pseudoinverse. Using a relative Jacobian, the tool path is resolved into joint trajectories at the acceleration level. This paper presents a new method for selecting the weighting matrix based on the proximity of the joint torques to saturation limits. This weighting reduces the joint accelerations contributing the most to the torques near saturation, thereby reducing the joint torques. The accelerations of other joints increase to satisfy the increased demand. The effectiveness of the acceleration and torque redistribution algorithm has been demonstrated via extensive simulations.     

Computing efforts allocation for ordinal optimization and discreteevent simulation

Ordinal optimization has emerged as an efficient technique for simulation and optimization. Exponential convergence rates can be achieved in many cases. In this paper, we present a new approach that can further enhance the efficiency of ordinal optimization. Our approach intelligently determines the optimal number of simulation replications (or samples) and significantly reduces the total simulation cost. Numerical illustrations are included. The results indicate that our approach can obtain an additional 74% computation time reduction above and beyond the reduction obtained through the use of ordinal optimization for a 10-design example     

The design and development of suspended handles for reducing hand-arm vibration in petrol driven grass trimmer

The portable petrol driven grass trimmer is identified as a type of machine whose operator can be subjected to large magnitude of hand-arm vibration. These vibrations can cause complex vascular, neurological and musculoskeletal disorder, collectively named as hand-arm vibration syndrome. The vibration total level on the handle of grass trimmer of 11.30 m/s² was measured, and it has reached the exposure limit value of 5.0 m/s² for daily vibration exposure A(8). New suspended handles were designed to reduce the vibration level. Three different prototype handles with rubber mounts were designed. Handles were made of different materials, and the distance of rubber mounts were varied. From the study, it was observed that not all the handles with rubber mounts were effective in reducing hand-arm vibration. The reduction of vibration depended on the handle material and distance installed between rubber mount and vibration transmissibility of handle-isolation system. Subjective ratings of perception of vibration were measured, and the results indicated that operators were not fully aware of the level of vibration. A prototype handle that is made of heavier material results in the lowest hand-arm vibration of 2.69 m/s². The new handle has significantly reduced the vibration total value by 76% compare with the existing commercial handle.

Relevance to industry

Large numbers of workers are employed to perform grass trimming job in many developing countries. This paper presents the effect of handle types (commercial and prototype) on the commonly used grass trimmer.     

虚拟转速转矩功率测试系统

设计基于虚拟仪器技术的转速、转矩、功率自动测试系统。该系统采用图形化编程语言LabVIEW语言设计，能够实现对旋转轴动力参数转速、转矩、功率的测量，并能实现数据的自动采集、保存、处理。由于该虚拟测试系统采用无线网络进行数据传输，其信号采集与信号处理相分离，对于移动机械和作业环境恶劣的测试场所，其应用范围广。     

Neural networks and genetic algorithms can support human supervisory control to reduce fossil fuel power plant emissions

Artificial neural networks and genetic algorithms are two intelligent approaches initially targeted to model human information processing and natural evolutionary process, with the aim of using the models in problem solving. During the last decade these two intelligent approaches have been widely applied to a variety of social, economic and engineering systems. In this paper, they have been shown as modelling tools to support human supervisory control to reduce fossil fuel power plant emissions, particularly NO_x emissions. Human supervisory control of fossil fuel power generation plants has been studied, and the need of an advisory system for operator support is emphasized. Plant modelling is an important block in such an advisory system and is the key issue of this study. In particular, three artificial neural network models and a genetic algorithm-based grey-box model have been built to model and predict the NO_x emissions in a coal-fired power plant. In non-linear dynamic system modelling, training data is always limited and cannot cover all system dynamics; therefore the generalization performance of the resultant model over unseen data is the focus of this study. These models will then be used in the advisory system to support human operators on aspects such as task analysis, condition monitoring and operation optimization, with the aim of improving thermal efficiency, reducing pollutant emissions and ensuring that the power system runs safely.     

Pneumatic tool torque reaction: reaction forces, displacement, muscle activity and discomfort in the hand-arm system

Reaction forces, hand-arm displacement, muscle activity and discomfort ratings were studied during the securing of threaded fasteners with three angle nutrunners with different shut-off mechanisms, but with the same spindle torque (72-74 Nm). The three tools were tested according to the method specified in ISO 6544. One of the tools had an almost instantaneous shut-off. Another had a more slowly declining torque curve. For the third tool the maximum torque was maintained for a while before shut-off. Twelve male subjects participated in the study. A force platform measured the reaction force between the subject and the floor. The option of the hand-arm system and the shoulder was measured with an optoelectronic measuring system. The muscle activity (EMG) in six muscles in the arm and shoulder was measured with surface electrodes. Significant differences in the arm movements and ground reaction forces were found between the three tools. The smallest values were found with the fast shut-off tool while the delayed shut-off tool caused the largest values. The EMG measures gave inconsistent response patterns. Discomfort ratings were highly correlated with the time for which the tool torque exceeded 90% of peak preset torque, but the time for which the tool torque exceeded 90% of peak calculated by the method specified in ISO 6544. Nutrunners with a shut-off mechanism that causes a slowly decreasing torque or a torque that is maintained for a while before shut-off should be avoided. If no substitutes are available, then a torque reaction bar should be mounted on the tool.     

Alternative computer mouse design and testing to reduce finger extensor muscle activity during mouse use

OBJECTIVE: The purpose of this study was to design and test alternative computer mouse designs that attempted to reduce extensor muscle loading of the index and middle fingers by altering the orientation of the button switch direction and the force of the switch. BACKGROUND: Computer users of two-button mouse designs exhibit sustained lifted finger behaviors above the buttons, which may contribute to hand and forearm musculoskeletal pain associated with intensive mouse use. METHODS: In a repeated-measures laboratory experiment, 20 participants completed point-and-click, steering, and drag tasks with four alternative mouse designs and a reference mouse. Intramuscular and surface electromyography (EMG) measured muscle loading, and movement times recorded by software provided a measure of performance. RESULTS: Changing the direction of the switch from a conventional downward to a forward design reduced (up to 2.5% maximum voluntary contraction [MVC]) sustained muscle activity (10th percentile EMG amplitude distribution) in the finger extensors but increased (up to 0.6% MVC) flexor EMG and increased movement times (up to 31%) compared with the reference mouse (p < .001). Implementing a high switch force design also increased flexor EMG but did not differ in movement times compared with the reference mouse (p < .001). CONCLUSION: The alternative mouse designs with altered switch direction reduced sustained extensor muscle loading; however, trade-offs with higher flexor muscle loading and lower performance existed. APPLICATION: Potential applications of this study include ergonomic and human computer interface design strategies in reducing the exposure to risk factors that may lead to upper extremity musculoskeletal disorders.     

Integrated torque vectoring and power management framework for electric vehicles

An integrated vehicle control framework is presented, which uses torque vectoring across independently driven wheels for control. The approach is general in nature, but is particularly well suited for electric vehicles due to increased control bandwidth. The novel algorithm optimizes wheel torque outputs in real time, constraining against power management, traction control, chassis configuration, actuator limits, and fault-case limitations. The structure is modular, and designed to adapt for differing vehicles with minimal re-tuning. Simulation and experimental results are provided for a modified electric SUV platform, under a range of dynamic maneuvers in 4WD, FWD, and RWD modes.     

EPS用SAW扭矩传感器结构优化及算法

针对市场上已有的车载电动助力转向系统(EPS)扭矩传感器存在易受噪声干扰、供电困难等缺点,结合声表面波(SAW)器件灵敏度高、抗干扰能力强等特点,提出了根据SAW原理对转向扭矩测量的方案。基于车载EPS使用环境复杂、温度变化大的特点,提出了一种可以消除温度影响的EPS用SAW扭矩传感器结构设计方案。在信号处理方面,针对M-Rife算法在对频率估计时,估计结果总体会发生频率偏移和误差过大的问题,提出了一种基于Welch和迭代插值算法对M-Rife算法改进的新算法。仿真和试验结果表明:改进的算法在估计EPS用SAW扭矩传感器频率信号方面拥有较好的精度,优于单独使用M-Rife算法。     

Compact and lightweight optical torque sensor for robots with increased range

This paper describes the development of a compact and lightweight optical torque sensor for robots with increased range. The torque generated can only be measured by placing a torque sensor on each joint, which makes the joint bulky and heavy adding extra load to be carried by robots. In this paper, we propose a compact and lightweight design for the torque sensor. This sensor can measure torque of robot's links by detecting torsion. The optical technique is used to detect angular displacement in the joints. As optical technique is immune to electromagnetic interference, light weight, and it also required simple electronics. The torque can be calculated by using torque and twist angle relation. The proposed design is simulated by FEM software (ANSYS), and it shows successful measurements of the torque with a load capacity of 100 Nm, which is sufficient for the torque generated in robot's joints. The designed optical torque sensor is manufactured by electrical discharge machining (EDM). The optical torque sensor is calibrated and several experiments are conducted to ensure its feasibility with the robot.     

工业传动轴转矩实时检测与数据分析系统设计

针对工业传动轴转矩研究的要求,设计了一种基于STC12C5A60S2单片机技术、结合AD7705模数转换器数据采集及nRF24L01无线模块进行数据通信的有转矩实时检测与数据分析的系统。系统的检测模块安装于传动轴上,通过无线模块将检测信息传送至接收模块,接收模块再把数据传送至上位机进行转矩实时监控与数据分析。给出了系统硬件设计的原理电路及软件设计的程序流程图,同时给出了系统的上位机操作界面,系统运行良好,具有较好的应用性和可移植性。     

Passivity-based torque and flux tracking for induction motors with magnetic saturation

An observer-based, globally asymptotically stable torque and rotor flux magnitude tracking controller for induction motors under magnetic saturation is proposed. The controller is synthesized using the passivity-based techniques. The paper considers a magnetically saturated π-model of the motor without any simplifying assumptions. Motor fluxes are reconstructed by a closed-loop observer. Closed-loop stability of the overall scheme including the observer is demonstrated. Simulation results are given to illustrate the proposed scheme.     

Fuzzy logic controller and cascade inverter for direct torque control of IM

In this paper, a five-level cascaded H-bridge multilevel inverters topology is applied on induction motor control known as direct torque control (DTC) strategy. More inverter states can be generated by a five-level inverter which improves voltage selection capability. This paper also introduces two different control methods to select the appropriate output voltage vector for reducing the torque and flux error to zero. The first is based on the conventional DTC scheme using a pair of hysteresis comparators and look up table to select the output voltage vector for controlling the torque and flux. The second is based on a new fuzzy logic controller using Sugeno as the inference method to select the output voltage vector by replacing the hysteresis comparators and lookup table in the conventional DTC, to which the results show more reduction in torque ripple and feasibility of smooth stator current. By using Matlab/Simulink, it is verified that using five-level inverter in DTC drive can reduce the torque ripple in comparison with conventional DTC, and further torque ripple reduction is obtained by applying fuzzy logic controller. The simulation results have also verified that using a fuzzy controller instead of a hysteresis controller has resulted in reduction in the flux ripples significantly as well as reduces the total harmonic distortion of the stator current to below 4 %.     

A new FEM approach for field and torque simulation of electrostatic microactuators

A novel finite-element method (FEM) floating-conductor formulation for the numerical electromagnetic analysis of electrostatic microactuators is presented and discussed in this paper. It is based on the assumption that the moving part of the microdevice can be modeled as a perfect conductor and leads to a considerable reduction of the mesh size, as the region occupied by the moving part does not need to be discretized at all. It is also shown that the developed formulation can be easily coupled with the well-known method of equivalent charges for the computation of the driving torque acting upon the rotor of the microdevice. This coupling is performed directly in terms of variables involved in the solution process of the final algebraic system and it allows acquiring torque information without any postprocessing operation. The proposed approach has been applied to the analysis of an electrostatic micromotor with radial field. When compared to simulations obtained with a commercial FEM electromagnetic code using a classical high-permittivity formulation, this method proves to be accurate and exhibits an overall reduction of preprocessing, processing and postprocessing time.