Concept of an exoskeleton for industrial applications with modulated impedance based on Electromyographic signal recorded from the operator

The introduction of an active exoskeleton that enhances the operator power in the manufacturing field was demonstrated in literature to lead to beneficial effects in terms of reducing fatiguing and the occurrence of musculo-skeletal diseases. However, a large number of manufacturing operations would not benefit from power increases because it rather requires the modulation of the operator stiffness. However, in literature, considerably less attention was given to those robotic devices that regulate their stiffness based on the operator stiffness, even if their introduction in the line would aid the operator during different manipulations respect with the exoskeletons with variable power. In this thesis the description of the command logic of an exoskeleton for manufacturing applications, whose stiffness is modulated based on the operator stiffness, is described. Since the operator stiffness cannot be mechanically measured without deflecting the limb, an estimation based on the superficial Electromyographic signal is required. A model composed of 1 joint and 2 antagonist muscles was developed to approximate the elbow and the wrist joints. Each muscle was approximated as the Hill model and the analysis of the joint stiffness, at different joint angle and muscle activations, was performed. The same Hill muscle model was then implemented in a 2 joint and 6 muscles (2J6M) model which approximated the elbow-shoulder system. Since the estimation of the exerted stiffness with a 2J6M model would be quite onerous in terms of processing time, the estimation of the operator end-point stiffness in realtime would therefore be questionable. Then, a linear relation between the end-point stiffness and the component of muscle activation that does not generate any end-point force, is proposed. Once the stiffness the operator exerts was estimated, three command logics that identifies the stiffness the exoskeleton is required to exert are proposed. These proposed command logics are: Proportional, Integral 1 s, and Integral 2 s. The stiffening exerted by a device in which a Proportional logic is implemented is proportional, sample by sample, to the estimated stiffness exerted by the operator. The stiffening exerted by the exoskeleton in which an Integral logic is implemented is proportional to the stiffness exerted by the operator, averaged along the previous 1 second (Integral 1 s) or 2 seconds (Integral 2 s). The most effective command logic, among the proposed ones, was identified with empirical tests conducted on subjects using a wrist haptic device (the Hi5, developed by the Bioengineering group of the Imperial College of London). The experimental protocol consisted in a wrist flexion/extension tracking task with an external perturbation, alternated with isometric force exertion for the estimation of the occurrence of the fatigue. The fatigue perceived by the subject, the tracking error, defined as the RMS of the difference between wrist and target angles, and the energy consumption, defined as the sum of the squared signals recorded from two antagonist muscles, indicated the Integral 1 s logic to be the most effective for controlling the exoskeleton. A logistic relation between the stiffness exerted by the subject and the stiffness exerted by the robotic devices was selected, because it assured a smooth transition between the maximum and the minimum stiffness the device is required to exert. However, the logistic relation parameters are subject-specific, therefore an experimental estimation is required. An example was provided. Finally, the literature about variable stiffness actuators was analyzed to identify the most suitable device for exoskeleton stiffness modulation. This actuator is intended to be integrated on an existing exoskeleton that already enhances the operator power based on the operator Electromyographic signal. The identified variable stiffness actuator is the DLR FSJ, which controls its stiffness modulating the preload of a single spring

Resistance exercise in men receiving androgen deprivation therapy for prostate cancer

This thesis encompasses two literature reviews (chapter 2 & 3) and two experimental chapters (4 and 5) examining the available literature on exercise and cancer, resistance training and its anabolic responses in older men and women, the side effects of Androgen Deprivation Therapy (ADT) for prostate cancer and finally, the role of resistance exercise as a clinical intervention to counteract such changes as an adjuvant therapy

"Production Ergonomics

"Production ergonomics – the science and practice of designing industrial workplaces to optimize human well-being and system performance – is a complex challenge for a designer. Humans are a valuable and flexible resource in any system of creation, and as long as they stay healthy, alert and motivated, they perform well and also become more competent over time, which increases their value as a resource. However, if a system designer is not mindful or aware of the many threats to health and system performance that may emerge, the end result may include inefficiency, productivity losses, low working morale, injuries and sick-leave. To help budding system designers and production engineers tackle these design challenges holistically, this book offers a multi-faceted orientation in the prerequisites for healthy and effective human work. We will cover physical, cognitive and organizational aspects of ergonomics, and provide both the individual human perspective and that of groups and populations, ending up with a look at global challenges that require workplaces to become more socially and economically sustainable. This book is written to give you a warm welcome to the subject, and to provide a solid foundation for improving industrial workplaces to attract and retain healthy and productive staff in the long run.

Exercise Recommendations for Cardiac Patients with Chronic Nonspecific Low Back Pain

Musculoskeletal comorbidities (MSKCs) are the most frequent cause of activity limitations in persons with cardiovascular disease (CVD) and affect as many as 70% of this population. It has been observed that over 50% of new outpatient cardiac rehabilitation participants experience some musculoskeletal pain, with back pain reported by up to 38% of cardiac rehabilitation patients. Back pain can limit performance of activities of daily living (ADLs) and reduce exercise tolerance and compliance during outpatient cardiac rehabilitation (CR). This article will describe ways to facilitate CR exercise participation in patients who have comorbid, chronic nonspecific low back pain (CNSLBP) and have been medically cleared to exercise

Risk factors and the effectiveness of back belts in the prevention of back pain amongst forklift drivers subject to whole body vibration exposure

Motivation: Back pain is a major cause of absenteeism, lost work time and increased compensation and medical costs amongst workers and has been estimated to cost $20 billion annually in the United States. Back pain has long been associated with the driving of forklifts, and is a complex area of occupational health and safety, having many risk factors leading to musculo-skeletal injury. The health effects in this occupational group in South Africa, could be affecting upwards of 90 000 forklift drivers, and has a great direct and indirect influence on people's health at work as well as productivity and the economy. Purpose: To characterise the problem of back pain amongst forklift drivers with a view to reducing the morbidity from back pain, by evaluating the effectiveness or the use of back belts. Aim: To identify risk factors associated with back pain amongst forklift drivers at Portnet (handling wharf side cargo) in two cohorts of forklift drivers one using back belts and one control group, and to evaluate the relationship between back pain, the occupational environment (i.e.: forklift driving) and other associated factors, in order to establish the effectiveness of back belts in decreasing the severity and prevalence of back pain amongst forklift drivers. Objectives: 1.) To describe demographic and other relevant back pain risk factors in the two cohorts and to identify any significant differences between them. 2.) To characterise the compliance and frequency of use of the back belts by the user group. 3.) To measure vibration experienced in typical driving activities in the study population in order to characterise whole-body vibration exposures of the study subjects. 4.) To ascertain opinions and beliefs regarding back belts amongst users. 5.) To analyse, characterise and determine if any significant differences exist between the two groups as to the prevalence and severity of back pain, and what factors are associated with increased risk of back pain. Specifically to identify whether (a.) The frequency and/or intensity of use of back belts are associated with reduced risk for back pain, when controlling for all other risk factors, and (b.) Whether other factors modify this relationship. Study Design: Cross Sectional Study Design Subjects: Drivers of 3, 4, 4.5 and 5 ton forklifts in the permanent employment of Portnet, Durban, from the Point, Maydon Wharf (back belt group) and Combi-Terminal (control group) areas. Main Outcome Measures: Onset of back pain after starting driving, prevalence of regular back pain (ever), point prevalence (pain today), 1 year prevalence, severity of back pain, duration of pain, and treatment/medication sought for back pain. Results: The majority of forklift drivers (89%) in the study suffer from chronic back pain that is of a constant severity, and is significantly linked to the driving activities. The back belt wearers were more likely to suffer from back pain then the non-users (92% vs 80%). However, the belt wearers reported less severe pain than the control group, which could indicate the presence of a placebo effect related to the belt use. The belt users were more likely to suffer from pain of a longer duration, with less fluctuation in severity than the controls, and therefore a more constant type of pain (44% vs 41 %). The majority of bell wearers expressed the belief that the belts helped to reduce the back pain (81%). However, more objective measures do not bear out this conclusion when prevalence and severity of pain are compared to the control group. Drivers with back pain were more likely to wear the back belts and compliance was reduced as the prevalence of pain was reduced. These results may have been confounded by variations in the whole-body vibration exposure in the various test areas, and the inability to characterise individual whole-body vibration exposures and dose-response relationships. Conclusion: The prevalence of back pain in this study was high, with most drivers suffering from pain in the lower back region (79%), which was characterised as constant or chronic pain experienced either during or shortly after driving. Whole-body vibration levels were high in all test areas (1.9 m/s⁻², 1.3 m/s⁻² and 1.1 m/s⁻² predicted), and consistently exceeded the EEC machinery directive standards of 0.5 m/s⁻². Compliance with the use of back belts amongst drivers was high (90%), with most drivers (76%) wearing the belts on a regular basis whilst driving. The evidence for the effectiveness of back belts as a control measure against whole-body vibration remains obscure, and other more tested controls such as engineering, administrative and training of drivers should be implemented to address the problem following a holistic approach

Work-related upper limb disorder:- An investigative study

The primary aim of occupational health staff within a manufacturing company is to ensure the health and well being of the employees are safeguarded. The aim may be difficult to achieve as it goes directly against the ethos of business, i.e. making money. It is the researcher's experience that company owners, especially Far Eastern owners, are disinclined to introduce health and safety measures that cost money. The study is conducted in an electronic company (Company X) in the northeast of England, owned by foreign nationals. Retrospective examination of accident, sickness and absenteeism records reveal that work-related upper limb disorder (WRULD) is apparent and upper limb discomfort is a significant problem in Соmpany X. Research shows that the principle of job rotation tends to reduce fatigue and the incidence of WRULD, consequently sickness and absenteeism and labour turnover will also be reduced. In Company X physiological stress to the limb is highly relevant to the production line workers, based on case studies of employees with work-related upper limb disorder. This led to conducting a study of two sites building different electrical equipment. 80 employees participated in the study which involved monitoring the employees on six paced production lines in the Personal Computer Monitor factory PCM which included seven teams and employees in five teams on four production lines in the Microwave Oven Factory. A semi paced line, the Bent Tool Machine BTM in MWO were also involved in the job rotation experiment. Discomfort scale measurements were administered to all that took part and an extra objective measurement of grip strength was provided by the employees in the BTM to provide information on fatigue. A comparison between grip strength and discomfort was analysed for any con-elation. The main data collection took place between September and December 2000.There is some evidence that the differences in discomfort is caused by job rotation as where job rotation was taking place the employees in the study had lower levels of discomfort than those on non- rotational duties. In the CDT prep job PCM where job rotation was taking place a comparison between job rotation and the non-rotation group with regard to discomfort in body parts differed (Fisher's exact test, p=0.05).The job action analysis that was designed specifically for the production line environment allowed comparisons of upper limb score for different jobs. It would appear that regular job analysis should be introduced as a matter of practice in Company X in the future. The study demonstrated the importance of prevention and innovation ergonomics and there was evidence to suggest that the occupational health department should adopt an active role in the future for the benefit of the employees and the financial survival of the Company

Analysis of Electrical Activity of the Core Muscles Exposed to Whole-Body Vibrations While Driving a Tractor Trailer Using Electromyography device

Lower back disorders are observed to be the most significant problem for most of the industrial workers who operate commercial vehicles. A person sitting can have 40% higher load on the lumbar spine than when standing. Human core muscles related to spinal movement respond to rapid potential motions related to external acceleration inputs of vibration in order to control body posture, the increased muscle tension can result in muscle fatigue. The over use of muscles, vibration exposure combined with dehydration of spine and long term seating can lead to lower back pain and axial discomfort to the drivers. Electromyography (EMG) is a technique used to monitor and analyze the electrical activation of the muscle. It has been found that the human spine has a natural frequency of 4-8Hz for natural upper body motion caused by curvature motion for the human spine. Trucks have historically produced the critical frequency which resulted in spinal problems for drivers. The purpose of air-ride seats is to reduce the critical frequency amplitudes. Muscular tension can move the natural frequencies to higher level to evaluate the response of the muscle to the expanded acceleration levels in the range of the spinal natural frequency. A Flex Comp Infinity device, Sonosens® monitor and accelerometers are mounted on the driver of the tractor trailer to collect EMG, ultrasound and acceleration data, respectively. Three testing trials are performed to examine the EMG data, which is correlated with the ultrasonic data and acceleration data collected during the tests. Standard data was collected on the driver using the standard commercial long hall tractor trailer on normal roads. The main purpose of the current research is to collect and analyze the physiological activity of the Erector spinae, Gluteus medius and Rectus abdominis muscles that relate to the lower back disorders. Present thesis work also examines spinal motions of the human body when exposed to whole-body vibrations. The study results show that the Erector spinae muscle activity is higher than that of Rectus abdominis and Gluteus medius muscles. Also the muscle fatigue on all the core muscles is observed to occur after 1hr 40 mins to 2 hr, and lasts for nearly 10 mins.The EMG results are compared to the acceleration and ultrasonic data, which were also collected during the test. It is observed that approximately 75% of the ultrasonic results and 60% of acceleration data correlate with EMG results. More accurate results can be expected if more tests are carried out. This research is highly useful to carry out further investigation in the areas of whole body vibration and the muscular response to reduce the level of excitation

Non-linear actuators and simulation tools for rehabilitation devices

Mención Internacional en el título de doctorRehabilitation robotics is a field of research that investigates the applications of robotics in motor function therapy for recovering the motor control and motor capability. In general, this type of rehabilitation has been found effective in therapy for persons suffering motor disorders, especially due to stroke or spinal cord injuries. This type of devices generally are well tolerated by the patients also being a motivation in rehabilitation therapy. In the last years the rehabilitation robotics has become more popular, capturing the attention at various research centers. They focused on the development more effective devices in rehabilitation therapy, with a higher acceptance factor of patients tacking into account: the financial cost, weight and comfort of the device. Among the rehabilitation devices, an important category is represented by the rehabilitation exoskeletons, which in addition to the human skeletons help to protect and support the external human body. This became more popular between the rehabilitation devices due to the easily adapting with the dynamics of human body, possibility to use them such as wearable devices and low weight and dimensions which permit easy transportation. Nowadays, in the development of any robotic device the simulation tools play an important role due to their capacity to analyse the expected performance of the system designed prior to manufacture. In the development of the rehabilitation devices, the biomechanical software which is capable to simulate the behaviour interaction between the human body and the robotics devices, play an important role. This helps to choose suitable actuators for the rehabilitation device, to evaluate possible mechanical designs, and to analyse the necessary controls algorithms before being tested in real systems. This thesis presents a research proposing an alternative solution for the current systems of actuation on the exoskeletons for robotic rehabilitation. The proposed solution, has a direct impact, improving issues like device weight, noise, fabrication costs, size an patient comfort. In order to reach the desired results, a biomechanical software based on Biomechanics of Bodies (BoB) simulator where the behaviour of the human body and the rehabilitation device with his actuators can be analysed, was developed. In the context of the main objective of this research, a series of actuators have been analysed, including solutions between the non-linear actuation systems. Between these systems, two solutions have been analysed in detail: ultrasonic motors and Shape Memory Alloy material. Due to the force - weight characteristics of each device (in simulation with the human body), the Shape Memory Alloy material was chosen as principal actuator candidate for rehabilitation devices. The proposed control algorithm for the actuators based on Shape Memory Alloy, was tested over various configurations of actuators design and analysed in terms of energy eficiency, cooling deformation and movement. For the bioinspirated movements, such as the muscular group's biceps-triceps, a control algorithm capable to control two Shape Memory Alloy based actuators in antagonistic movement, has been developed. A segmented exoskeleton based on Shape Memory Alloy actuators for the upper limb evaluation and rehabilitation therapy was proposed to demosntrate the eligibility of the actuation system. This is divided in individual rehabilitation devices for the shoulder, elbow and wrist. The results of this research was tested and validated in the real elbow exoskeleton with two degrees of freedom developed during this thesis.Programa Oficial de Doctorado en Ingeniería Eléctrica, Electrónica y AutomáticaPresidente: Eduardo Rocón de Lima.- Secretario: Concepción Alicia Monje Micharet.- Vocal: Martin Stoele