Equivalent weight: Application of the assessment method on real task conducted by railway workers wearing a back support exoskeleton

Commonly used risk indexes, such as the NIOSH Lifting Index, do not capture the effect of exoskeletons. This makes it difficult for Health and Safety professionals to rigorously assess the benefit of such devices. The community requires a simple method to assess the effectiveness of back-support exoskeleton's (BSE) in possibly reducing ergonomic risk. The method introduced in this work is termed “Equivalent Weight†(EqW) and it proposes an interpretation of the effect built on the benefit delivered through reduced activation of the erector spinae (ES). This manifests itself as an apparent reduction of the lifted load perceived by the wearer. This work presents a pilot study where a practical application of the EqW method is used to assess the ergonomic risk in manual material handling (MMH) when using a back support exoskeleton (StreamEXO). The results are assessed by combining observational measurements from on-site testing with five different workers and quantitative measures of the muscle activity reduction achieved during laboratory evaluation with ten workers. These results will show that when lifting, lowering, and carrying a 19 kg load the StreamEXO can reduce risk by up to two levels (from “high†to “low†) in the target sub-tasks. The Lifting index (LI) was reduced up to 64% when examining specific sub-tasks and the worker's movement conduction

Systematic framework for performance evaluation of exoskeleton actuators

AbstractWearable devices, such as exoskeletons, are becoming increasingly common and are being used mainly for improving motility and daily life autonomy, rehabilitation purposes, and as industrial aids. There are many variables that must be optimized to create an efficient, smoothly operating device. The selection of a suitable actuator is one of these variables, and the actuators are usually sized after studying the kinematic and dynamic characteristics of the target task, combining information from motion tracking, inverse dynamics, and force plates. While this may be a good method for approximate sizing of actuators, a more detailed approach is necessary to fully understand actuator performance, control algorithms or sensing strategies, and their impact on weight, dynamic performance, energy consumption, complexity, and cost. This work describes a learning-based evaluation method to provide this more detailed analysis of an actuation system for ourXoTrunkexoskeleton. The study includes: (a) a real-world experimental setup to gather kinematics and dynamics data; (b) simulation of the actuation system focusing on motor performance and control strategy; (c) experimental validation of the simulation; and (d) testing in real scenarios. This study creates a systematic framework to analyze actuator performance and control algorithms to improve operation in the real scenario by replicating the kinematics and dynamics of the human–robot interaction. Implementation of this approach shows substantial improvement in the task-related performance when applied on a back-support exoskeleton during a walking task

Laparoscopic Tissue Retractor Based on Local Magnetic Actuation

Magnetic instruments for laparoscopic surgery have the potential to enhance triangulation and reduce invasiveness, as they can be rearranged inside the abdominal cavity and do not need a dedicated port during the procedure. Onboard actuators can be used to achieve a controlled and repeatable motion at the interface with the tissue. However, actuators that can fit through a single laparoscopic incision are very limited in power and do not allow performance of surgical tasks such as lifting an organ. In this study, we present a tissue retractor based on local magnetic actuation (LMA). This approach combines two pairs of magnets, one providing anchoring and the other transferring motion to an internal mechanism connected to a retracting lever. Design requirements were derived from clinical considerations, while finite element simulations and static modeling were used to select the permanent magnets, set the mechanism parameters, and predict the lifting and supporting capabilities of the tissue retractor. A three-tier validation was performed to assess the functionality of the device. First, the retracting performance was investigated via a benchtop experiment, by connecting an increasing load to the lever until failure occurred, and repeating this test for different intermagnetic distances. Then, the feasibility of liver resection was studied with an ex vivo experiment, using porcine hepatic tissue. Finally, the usability and the safety of the device were tested in vivo on an anesthetized porcine model. The developed retractor is 154 mm long, 12.5 mm in diameter, and weights 39.16 g. When abdominal wall thickness is 2 cm, the retractor is able to lift more than ten times its own weight. The model is able to predict the performance with a relative error of 9.06 ± 0.52%. Liver retraction trials demonstrate that the device can be inserted via laparoscopic access, does not require a dedicated port, and can perform organ retraction. The main limitation is the reduced mobility due to the length of the device. In designing robotic instrument for laparoscopic surgery, LMA can enable the transfer of a larger amount of mechanical power than what is possible to achieve by embedding actuators on board. This study shows the feasibility of implementing a tissue retractor based on this approach and provides an illustration of the main steps that should be followed in designing a LMA laparoscopic instrument

Back-Support Exoskeleton Control Strategy for Pulling Activities: Design and Preliminary Evaluation

The execution of manual material handling activities in the workplace exposes workers to large lumbar loads that increase the risk of musculoskeletal disorders and low back pain. In particular, the redesign of the workplace is making the execution of pulling activities more common, as an alternative to lifting and carrying tasks. The biomechanical analysis of the task revealed a substantial activation of the spinal muscles. This suggests that the user may benefit from the assistance of a back-support exoskeleton that reduces the spinal muscle activity and their contribution to lumbar compression. This work addresses this challenge by exploiting the versatility of an active back-support exoskeleton. A control strategy was specifically designed for assisting pulling that modulates the assistive torques using the forearm muscle activity. These torques are expected to adapt to the user's assistance needs and the pulled object mass, as forearm muscle activity is considered an indicator of grip strength. We devised laboratory experiments to assess the feasibility and effectiveness of the proposed strategy. We found that, for the majority of the subjects, back muscle activity reductions were associated with the exoskeleton use. Furthermore, subjective measurements reveal advantages in terms of perceived support, comfort, ease of use, and intuitiveness

Wireless tissue palpation: Head characterization to improve tumor detection in soft tissue

For surgeons performing open procedures, the sense of touch is a valuable tool to directly access buried structures and organs, to identify their margins, detect tumors, and prevent undesired cuts. Minimally invasive surgical procedures provide great benefits for patients; however, they hinder the surgeon's ability to directly manipulate the tissue. In our previous work, we developed a Wireless Palpation Probe (WPP) to restore tissue palpation in Minimally Invasive Surgery (MIS) by creating a real-time stiffness distribution map of the target tissue. The WPP takes advantage of a field-based magnetic localization algorithm to measure its position, orientation, and tissue indentation depth, in addition to a barometric sensor measuring indentation tissue pressure. However, deformations of both the tissue and the silicone material used to cover the pressure sensors introduce detrimental nonlinearities in sensor measurements. In this work, we calibrated and characterized different diameter WPP heads with a new design allowing exchangeability and disposability of the probe head. Benchtop trials showed that this method can effectively reduce error in sensor pressure measurements up to 5% with respect to the reference sensor. Furthermore, we studied the effect of the head diameter on the device's spatial resolution in detecting tumor simulators embedded into silicone phantoms. Overall, the results showed a tumor detection rate over 90%, independent of the head diameter, when an indentation depth of 5 mm is applied on the tissue simulator

Wireless Tissue Palpation: head characterization to improve tumor detection in soft tissue

Abstract For surgeons performing open procedures, the sense of touch is a valuable tool to directly access buried structures and organs, to identify their margins, detect tumors, and prevent undesired cuts. Minimally invasive surgical procedures provide great benefits for patients; however, they hinder the surgeon's ability to directly manipulate the tissue. In our previous work, we developed a Wireless Palpation Probe (WPP) to restore tissue palpation in Minimally Invasive Surgery (MIS) by creating a real-time stiffness distribution map of the target tissue. The WPP takes advantage of a field-based magnetic localization algorithm to measure its position, orientation, and tissue indentation depth, in addition to a barometric sensor measuring indentation tissue pressure. However, deformations of both the tissue and the silicone material used to cover the pressure sensors introduce detrimental nonlinearities in sensor measurements. In this work, we calibrated and characterized different diameter WPP heads with a new design allowing exchangeability and disposability of the probe head. Benchtop trials showed that this method can effectively reduce error in sensor pressure measurements up to 5 % with respect to the reference sensor. Furthermore, we studied the effect of the head diameter on the devices spatial resolution in detecting tumor simulators embedded into silicone phantoms. Overall, the results showed a tumor detection rate over 90 %, independent of the head diameter, when an indentation depth of at 5 mm is applied on the tissue simulator

ARTICLE IN PRESS G Model

a b s t r a c t For surgeons performing open procedures, the sense of touch is a valuable tool to directly access buried structures and organs, to identify their margins, detect tumors, and prevent undesired cuts. Minimally invasive surgical procedures provide great benefits for patients; however, they hinder the surgeon's ability to directly manipulate the tissue. In our previous work, we developed a Wireless Palpation Probe (WPP) to restore tissue palpation in Minimally Invasive Surgery (MIS) by creating a real-time stiffness distribution map of the target tissue. The WPP takes advantage of a field-based magnetic localization algorithm to measure its position, orientation, and tissue indentation depth, in addition to a barometric sensor measuring indentation tissue pressure. However, deformations of both the tissue and the silicone material used to cover the pressure sensors introduce detrimental nonlinearities in sensor measurements. In this work, we calibrated and characterized different diameter WPP heads with a new design allowing exchangeability and disposability of the probe head. Benchtop trials showed that this method can effectively reduce error in sensor pressure measurements up to 5% with respect to the reference sensor. Furthermore, we studied the effect of the head diameter on the device's spatial resolution in detecting tumor simulators embedded into silicone phantoms. Overall, the results showed a tumor detection rate over 90%, independent of the head diameter, when an indentation depth of 5 mm is applied on the tissue simulator

Smart tools for railway inspection and maintenance work, performance and safety improvement

The rail sector faces significant challenges as a wide variety of heterogeneous working methods, the continued raising of the workforce average age, and the lack of young workers interested in such physically demanding work. STREAM supports LEAN execution of intelligent inspection and maintenance procebes promoting and implementing technologies to improve safety, prevent incidents and accidents, and support workers in maintenance activities. The ambition is to significantly enhance operational planning, safety, and performance while causing little change to current work procebes. STREAM contributes to two leading technologies: The OTA3M, a control platform adapted to existing excavators that provides autonomous multi-purpose operations enabling safe worker-machine collaboration. The MMPE is a modular multi-tasking exoskeleton developed to assist track workers during heavy activities.Peer reviewe

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns