Generally, steel balls are used to maintain rolling contacts on grooves of ball screws and bearings. When the ball screws and bearings are actuating, the balls are revolving around the grooves' orbit and rotating around the axis through the balls' center. To clarify the friction and noise caused by the motions, it is necessary to analyze in detail the contact condition and motion of the ball. This paper discusses a calculation method of bearing balls' motion, based on an assumption that the balls' orbital revolution and rotation is ruled by their contact points with the rolling grooves. Theoretical analysis and multibody simulation show the relationship between the initial contact points and the two points contact balls' motion.

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A fall prevention device that aims to protect user from injury when fall happens has been proposed. In the previous research, Origami Spring was proposed as an extendable mechanism to implement the fall prevention device and an extendable rigid link mechanism based on Origami Spring has been developed. However, the extendable mechanism was too large to equip for people because of the thickness of links and actuators. Also, the repeatability of its extension motion was rather low due to rattling and less constraints. In this research, improvement of portability of the extendable mechanism and repeatability has been investigated from mechanical design point of view. From the perspective of portability, a new prototype of the extendable mechanism has been fabricated by using thin links and thin actuators. As for the improvement of repeatability, constraint elements using spiral spring has been designed to implement desired relative motion between links. The feasibility of desired relative motion of the extendable mechanism was confirmed by kineto-static analysis of a planar model. Through experimental study of extension, effectiveness of proposed elements was validated.

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Geared transmissions are used in various machines such as automobile transmissions but these mechanisms lose driving force during shifting. A novel ratio variation system was proposed to solve this problem. This transmission mechanism uses noncircular gears which can realize the reduction ratios of two gears. In order to transmit rotation constantly, this noncircular gear pair must always be in mesh. Therefore, this report discusses the contact ratio of noncircular gears and shows a calculation result regarding the contact ratio.

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A surgical energy device is an apparatus that converts energy into heat to incise or coagulate tissues and organs. Its usage can cause thermal damage in an unexpected area of biological tissue. It is necessary to investigate temperature rise near the dissection part when developing new energy devices. This study aims to develop a biological tissue-mimicking phantom that can visualize temperature rise around 60 °C. We used OEGMA-based hydrogel and evaluated its elastic modulus to emulate the properties of biological tissue. The elasticity increased with increasing crosslinker concentration, reaching a maximum of 71.7 kPa. We observed that the hydrophobic crosslinker EGDMA did not precipitate in the gelation process in EGDMA concentrations ranging up to 0.100 M using the two-step gelation approach.

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This paper describes the elemental technology of a system that discriminates whether or not sputum is accumulated (whether or not suction is necessary) based on auscultation sounds using edge devices such as microcomputers, in order to support endotracheal suctioning (a procedure to suction sputum accumulated in the trachea), which is one of nursing tasks. Since a typical FFT library for microcomputers is used, the lung sounds are FFTed not for an entire breath but for a short span, and the machine learning and discrimination of normal and abnormal by frequency spectrum are performed to experimentally verify the discrimination performance. On a high-performance microcomputer SPRESENSE, lung sound data read from a wav files is FFTed over a short span (approximately 0.26 seconds), and the frequency spectrum is used to discriminate normal from abnormal using a neural network model that has been machine learned on a computer in advance. The results showed that the discrimination accuracy is reasonably good, approaching 90%.

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This paper proposes the application of an elastically constrained underactuated parallel mechanism as a leg mechanism to achieve soft landing of its foot to adapt uneven or unknown terrain. A planar 6-bar one-loop mechanism with 3DOF and two rotary actuators which links are constrained with torsional coil springs is assumed as a simple example of a leg mechanism. Inverse and forward kinetostatics analyses in cases of free leg and ground contact of its foot are achieved by taking account of virtual torque or ground reaction force. Contour maps of elastic energy, reaction force and driving torque with respect input angles are obtained and used for landing control strategy. Simulation results shows that the mechanism can achieve complete landing on inclined ground.

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This paper presents the effect of dynamic loads on the gravity compensation design of serial robots. In this study, the torque reduction index (TRI), the power reduction index (PRI), and the energy reduction index (ERI) are established to evaluate the dynamic performance of the robot. The significance of this study is that it can provide a comprehensive understanding of adopting a gravity compensation design for a robot with consideration of the dynamic loads. A three-degree-of-freedom (3-DoF) serial robot is taken as an example. The gravity compensation design for this robot is realized with the gear-spring mechanism (GSM) without using a parallelogram linkage. A case study is given to illustrate the performance of the gravity-compensated robot. It was shown that the gravity compensation design could reduce the actuator torque, power, and energy consumption of the robot even when the dynamic loads are considered. The effectiveness of the gravity compensation is more significant for low-speed operations.

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The authors focus on the fly-fishing to realize a casting by a small and low-power manipulator. This paper proposes a parameter identification method for analyzing real fly-fishing based on a rod dynamic model. First, the static measurement identifies parameters of the rod’s elasticity and derives the relationship between the center of gravity and the mass of each link. Then, all parameters are identified through the measurements of rod vibrations by the steepest descent method using a few variables, from approximating each link as a truncated cone. The validity of the proposed method was confirmed by comparing measurements and simulation using identified parameters.

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This paper discusses a concept for novel 3D super multi DOF robot arms utilizing electrostatic layer jamming. For various purposes, such as operation in limited spaces and dexterous operations, super multi DOF robot arms have been studied. Typically, in those robot arms, joints are independently controlled by corresponding wires and motors, which complicates the while structure. A previous study showed that jamming actuation can simplify the structure. Among jamming mechanisms, electrostatic layer jamming has shown its simplicity and high flexibility and is promising to realize compact and light-weight multi-DOF arms. In this paper, a prototype 5-DOF robot arm, which can move in 3D space, based on electrostatic layer jamming is introduced. A series of orthogonal joints equipped with electrostatic layer jamming brakes are cascaded to realize 3D motion. The prototype robot was driven by two pairs of stepper motors to create 3D postures. Although some engineering problems in the development were found, the prototype verified the basic concept for the super multi-DOF robot arm.

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Robot-assisted rehabilitation has proven to be effective in clinical practice, not only because of its ability to perform repetitive and intensive rehabilitation therapy but also because its rehabilitation outcome is not limited by the lack of experienced therapists or their fatigue due to long and repetitive rehabilitation sessions. Several robotic solutions have been proposed over time, but rarely have these solutions been successful, in particular due to the excessive bulk, discomfort, and joints alignment of the robotic solution. This paper lays the foundation for a preliminary synthesis of a wearable cable-driven parallel robot for wrist joint rehabilitation. Specifically, the synthesis focuses on defining an ad hoc geometric efficiency index to maximise the effective force required to achieve flexion-extension, radial-ulnar deviation and pronation-supination movements with the lowest possible cable tension. To consider lightness and wearability, the results of the synthesis are weighted to obtain a light and compact system that will be developed.

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In the field of robotic rehabilitation, the cable-driven parallel robots (CDPRs) are becoming an ideal solution for their characteristics including large workspace, easy reconfigurability, low-cost. This paper proposes a specifically developed graphic user-interface for the operation of planar cable-driven parallel robots. Its features are not limited to motion programming, but also for assisting in all evaluation and rehabilitation phases. The interface integrates a simulator allowing to check and avoid any undesired motion or pose as well as avoid collisions. The paper includes preliminary experimental results demonstrating the feasibility and usefulness of the proposed interface.

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This paper describes details of the development of skill evaluation system for laparoscopic surgical procedure. The measurement experiment was conducted for 70 surgeons, and the participants perform 2 tasks: tissue dissection around the aorta and renal parenchymal suturing/knotting using porcine cadaver. In the experiments, the movement of surgical instruments were recorded by motion capture (MoCap) system, and the motion indices were calculated. The participants grouped into three classes (novices, intermediates, and experts) according to their level of experience. Three classification algorithms: support vector machine (SVM), principal component based SVM (PCA-SVM), gradient boosting decision tree (GBDT) were utilized for developing the model of classifier. The accuracy of each model was assessed by nested and repeated k-fold cross validation. Regarding 3-class classification, the GBDT method resulted highest accuracy (the median of the accuracy is A_med = 68.6 %) in the dissection tasks. In the suturing/knotting tasks, PCA-SVM resulted highest accuracy (A_med = 58.4 %). Regarding 2-class classification (experts vs. intermediates/novices), the GBDT method resulted A_med = 72.9 % in the dissection task, and the PCA-SVM method resulted A_med = 69.2 % in the suturing task. This result shows the MoCap based skill evaluation system in wet-lab training could be a practical way to objectively assess trainees' surgical competence.

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Respiration is a complex biomechanical act involving different organs such as lungs and ribcage which is a complex system of bones and muscles. Respiratory monitoring is aimed for diagnostic purposes to assess respiratory efficiency with coordinated organs and thoracic structure movements. This paper presents a new device and a procedure for monitoring the movement of the rib cage of a person by analyzing the motion of a rib in order to determine the main characteristics of the thoracic movement that are related to the respiratory act in determining the expansion of the pulmonary organs. In particular, the design of an innovative device is presented for long-term monitoring following previous experiences with a non-invasive and easy-to-apply small device. Using a prototype of the Respirholter device, an experimentation campaign was carried out to characterize the use of the device and its efficiency as well as for a validation in diagnostic aspects on good-health volunteers. Illustrative results are reported that demonstrate the convenience of the designed device and the usefulness of the acquired data for a diagnostic characterization of respiration.

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The use of robotic technologies for caregiving and assistance has become a very interesting research topic in the field of robotics. For this reason, the researchers at Politecnico di Torino are developing robotic solutions for indoor assistance. This paper presents the DOT PAQUITOP project, which aims at developing a mobile robotic assistant for hospital environment. The mobile robot is composed of an omnidirectional platform, named PAQUITOP, a commercial 6 dof robotic arm, sensors for the vital sign patient monitoring and a tablet to interact with the user.

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The increased offshore construction rate has raised the problem of accuracy and safety of lifting operations carried out by crane ships more acutely. In this regard, researchers turn their attention to the problems of analyzing the hydrodynamic response of crane vessels during the equipment installation and construction of structures. For these studies, multibody dynamics mathematical modeling tools are used, as well as specialized CFD solvers, allowing to determine the impact of the sea environment on the floating bodies. Among a variety of such software, there are both commercial and free programs with their own calculation algorithms and capabilities. In this paper, attention is paid to the approach of modeling a floating crane ship in the time domain using open-source software WEC-Sim and Capytaine, which, in our opinion, have significant advantages over other similar codes. The description of the approach is followed by an example of calculation on an arbitrary configuration of a crane vessel.

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In this article, the results of nonlinear model predictive controllers that are used to generate optimized trajectories of omnidirectional robots equipped with spraying units for the perimeter of hazardous areas inside warehouses are presented, using a nonlinear model predictive controller. Results are provided for various trajectories along with consideration of controller performance.

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In this paper, the vibrational behavior of a gas microturbine was analyzed for several fuels. The study was carried out through discriminant analysis using statistical indices computed starting from accelerometer signals. Two rotation speeds were tested on the microturbine fueled with three different fuels. Such approach is able to classify turbine vibrational behavior as a function of fuel type. In particular, the classification is enhanced for one of the two tested speeds allowing good differentiation between the different types of fuels.

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