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The robotic wearable exoskeletons have been developed due to various advantages offered by these devices. These advantages are manifested by integrating the human and a robot into one system under the user's control, which motivated researchers to develop different exoskeletons through years. However, several advances in exoskeleton; still, dealing with the various technical challenges in designing these impressive devices is inevitably. This paper aims to introduce informative resources and quick guidance of various technical challenges as such information is critical for exoskeleton development. The constructive discussion is intended to encourage researchers, innovators and academia to be aware of these challenges. Finally, the contemporary research gaps with various challenges have been highlighted, which remain to be solved as well as some future directions in this field that will have far-reaching effects on developing exoskeletons.

Almost the half of mechanical energy of a human gait cycle is generated by a hip joint. Therefore, this paper discusses a rehabilitation hip exoskeleton, starting with the modeling, simulation and ending with controlling its hip joints. A MATLAB based simulation environment with the use of Simscape Multibody toolbox was utilized to design and control the robotic hip exoskeleton. More details of adding a series elastic actuators (SEA) to the hip joints with the mathematical model are presented. However, the linearised mathematical model of the entire exoskeleton was found in simulation software which establish the basic need of controlling hip joints. The trajectory tracking is commonly used of controlling rehabilitation exoskeleton and to ensure a safe and reliable motion tracking methods, two desired torque signals were tested and analysed with the optimal linear quadratic regulator (LQR). The experiments with two torque signals–representing the sit-to-stand (STS) and the walking activity, demonstrated good performance of the motion gait tracking based on torque signals of a healthy person, which is carried out in the simulation environment. Furthermore, some studies in a human robot interaction are also mentioned in this paper.

This paper presents the design strategy of a passive vibration isolator made form combination of elastomers and metal. The objective was to design & develop "Passive vibration isolator" to safeguard the sensitive electronics from vibration transmitted from due to road terrain. These electronics equipment’s were mounted on two racks placed side by side in a customized container, which in turn was fitted on a commercial vehicle. Two types of elastomers (Pure Rubber & Silicon Rubber) were chosen for carrying out the tensile tests to determine the stiffness parameters of these elastomers. Based on test results, elastomer material was chosen & mechanical design was perceived to prepare passive elastomer isolators of two types consisting of single layer and double layers. Mathematical Models were developed for each type of isolators along with electronics boxes. Finite Element Analysis (FEA) was carried out using ANSYS® workbench. In order to verify FEA results and to the effectiveness of both isolators’ types, two mock up electronics boxes were manufactured& integrated with designed single layer as well as double layer isolator. Vibration testing was carried out by employing the loading as per MIL-STD-810G on vertical, longitudinal & transversal directions on the two electronics boxes respectively. Both Finite Element Analysis (FEA) and testing results showed that single layer elastomer (pure rubber) has better isolation as compared to the two-layer elastomer. Later on, the single layered elastomer (pure rubber) passive isolators were manufactured & integrated with electronic units mounted inside mobile vehicle. Experimental data obtained using ISO 10816 Vibration Severity Standard for Vibration Analysis by carrying out the actual road trials of Mobile Vehicle on the intended pathways. The comparison of experimental data with FEA shows that proposed passive vibration isolator fulfills the vibration isolation requirement.

This paper presents a new strategy and circuit configuration composed of serially-connected PMOS devices operating in the subthreshold region for implementing ultra-highvalue resistors required in very low-frequency active-RC filters and bio-amplifiers. Depending on the application, signal bandwidth for instance in bio-amplifiers may vary from a few mHz up to a maximum of 10 kHz. Three different resistor structures are proposed to achieve ultra-high resistance. While ranging in the order of several TY, the proposed ultra-high-resistance pseudoresistors occupy a small on-chip silicon area, which is one of the main issues in the design of analog front-end circuits in ultra-low power implantable biomedical microsystems. In addition, these ultra-high-value resistors lead to the use of a small capacitance to create a very small cut-off frequency. Therefore, the large area to implement capacitances is also considerably reduced. The proposed resistor structures have very small variations about 7% and 12% in a wide input voltage range (-0.5 V +0.5 V), thus significantly improving the total harmonic distortion of bioamplifiers and the analog front-end of the system. Simulation results of different circuits designed in a 180nm CMOS technology, are shown to demonstrate the advantages of the proposed ultra-high-resistance pseudo-resistors.

Communication systems are a key element for the industry 4.0 revolution, where the remote access to the machinery is a fundamental part for the automation of tasks related to monitoring and control of the different industrial processes. There is an increasing interest in performing such communications using a wireless medium, as they offer several advantages as a lower cost, greater flexibility or the ability to operate in moving elements. However, existing works have showed that the achievable performance in the sub-6 GHz frequency bands is insufficient to cope with all the requirements, which motivated the analysis of the millimeter wave spectrum for these use cases. Industrial environments present a harsh condition for electromagnetic wave propagation, where the abundance of reflective surfaces can present difficulties to properly exchange information. Thus, a thorough analysis and characterization of the propagation through this kind of environment is necessary to develop protocols and standards accordingly. This work provides the results of measurements carried out in two industrial facilities, which are a university workshop and a pit oven building from a steel company. Metrics of the results are computed and discussed as well, where a significantly larger losses can be seen for the pit oven measurements compared to other industrial scenarios.

Communication systems are a key element for the industry 4.0 revolution, where the remote access to the machinery is a fundamental part for the automation of tasks related to monitoring and control of the different industrial processes. There is an increasing interest in performing such communications using a wireless medium, as they offer several advantages as a lower cost, greater flexibility or the ability to operate in moving elements. However, existing works have showed that the achievable performance in the sub-6 GHz frequency bands is insufficient to cope with all the requirements, which motivated the analysis of the millimeter wave spectrum for these use cases. Industrial environments present a harsh condition for electromagnetic wave propagation, where the abundance of reflective surfaces can present difficulties to properly exchange information. Thus, a thorough analysis and characterization of the propagation through this kind of environment is necessary to develop protocols and standards accordingly. This work provides the results of measurements carried out in two industrial facilities, which are a university workshop and a pit oven building from a steel company. Metrics of the results are computed and discussed as well, where a significantly larger losses can be seen for the pit oven measurements compared to other industrial scenarios.

Millimeter wave (mmWave) wireless technology is primarily considered for low latency communication in fifth-generation mobile technology (5G) and has the potential to revolutionize industrial automation and manufacturing processes. This article investigates multipath radio propagation in indoor industrial environments at the 24 GHz industrial, scientific and medical (ISM) mmWave frequency band. The wideband radio channel measurements were carried out in four different industrial environments in Sweden. The measurements were conducted using an affordable but highly competent in-house assembled mmWave testbed, reusing radio instruments available in our lab. The measurement environments were chosen based on their radio wave reflection characteristics. The multipath propagation characteristics are analyzed with respect to the power delay profile (PDP), coherence bandwidth, and root mean square (RMS) delay spread. Additionally, the Saleh-Valenzuela model parameters are estimated for these industrial environments.