New Trends in Mechanism and Machine Science

According to the topology design method of parallel mechanism based on position and orientation characteristic equations, a new type of three-translation parallel mechanism with symbolic forward position solution and partial motion decoupling is designed. Firstly, its topological characteristics such as position and orientation characteristic, degree of freedom and coupling degree, are analyzed and obtained. Secondly, using the kinematics modeling principle based on topological characteristics proposed by the author, the symbolic forward position solutions of the parallel mechanism are derived.

The damping mechanism of damping system using granules—applied to reduce vibration in structures with high natural frequency and small vibration displacement—was investigated. A computational model of a single-degree-of-freedom vibration system with a granular-material damper was constructed and used to study the mechanism of the granular-material damping system. On the basis of the fundamental idea that the damping effect of the granular-material damper is governed by the motion of the granules, the granules were classified as the following mass components: “relative-motion mass” and “equivalent added mass” in the translational motion and “rotational-motion mass” and “non-rotational-motion mass” in the rotational motion. The relationships of these mass components with the damping characteristics of the damper were then considered. Moreover, as for structures with high natural frequency and small vibration displacement, the relationships between the motion of the granules, “relative-motion mass” and “rotational-motion mass”, and damping ratio were investigated by experiments and calculations.

Four link twist angles are the design parameters for spherical 4R linkages: changing the magnitudes of the twist angles changes the motion characteristics of the linkage. A new quartic algebraic input-output equation for spherical four-bar linkages, obtained in another paper, contains four terms which each factor into pairs of distinct cubics in the link twist parameters. These eight cubic factors possess a symmetry that suggest they combine to form a shape that, at least locally, bears a remarkable resemblance to a pair of dual tetrahedra in the design parameter space of the link twists. In this paper we show that the location of points relative to the eight distinct cubic surfaces implies a complete classification scheme for all possible spherical 4R linkages. Moreover, we show that the design parameter spaces of both the spherical and planar 4R linkages, with suitable scaling, intersect in 12 lines which form the 12 edges of a pair of dual tetrahedra.

Two well known graphical methods based on Bobillier’s construction of the inflection pole and Bereis’ construction of Ball’s point on the inflection circle are used for many decades. In this paper a new general-purpose method of step-by-step vectorization of constructions like these is introduced. It is based on symplectic geometry in its simplest possible 2D case and is making use of loop closure equations exclusively. The vectorization process is coordinate and trigonometry free. The formulas found by this method are new and their correctness is easily verified by comparison with results of the corresponding graphical methods.

This paper has an interesting observation, i.e., the selection of the loop virtual variable position has an important effect on the direct kinematics analysis of PMs. The correct selection of the virtual variable position will directly affect the effectiveness of solving the direct kinematics of a PM and even affect the form of the direct kinematics. If the virtual variable position is properly selected, the symbolic solutions can be obtained. Otherwise, only closed-form solutions or numerical solutions can be obtained. A one-translation and one-rotation PM as an example is used to derive its symbolic direct kinematics for verification.

Function generation for finitely many positions and dead-center design problems are generally separately handled in the literature. This paper presents a mixed formulation for planar slider-crank linkages where three precision points and a folded or extended dead-center position are to be satisfied. The formulation results in an 8th degree univariate. Examples show that generally there are four real solutions, only two of which result in distinct solutions.

In this paper, using the vector and tensor calculus and the multidual algebra, a new computing method for studying the higher-order acceleration field properties in the case of the general rigid body motion is proposed. The results are coordinate-free and in a closed-form. Higher-order kinematics analysis of lower-pair serial chains with multidual algebra will be done. In particular cases, the properties for velocity, acceleration, jerk and jounce fields are given. This approach uses the morphism between the Lie group of the rigid displacements and the Lie group of the orthogonal multidual tensors.

It is known that parallel manipulators suffer from singular configurations. Evaluating the distance between a given configuration to the closest singular one is of interest for industrial applications (e.g. singularity-free path planning). For parallel manipulators of Stewart-Gough type, geometric meaningful distance measures are known, which are used for the computation of the singularity distance as the global minimizer of an optimization problem. In the case of hexapods and linear pentapods the critical points of the corresponding polynomial Lagrange function cannot be found by the Gröbner basis method due to the degree and number of unknowns. But this polynomial system of equations can be solved by software tools of numerical algebraic geometry relying on homotopy continuation. To gain experiences for the treatment of the mentioned spatial manipulators, this paper attempts to find minimal multi-homogeneous Bézout numbers for the homotopy continuation based singularity distance computation with respect to various algebraic motion representations of planar Euclidean/equiform kinematics. The homogenous and non-homogenous representations under study are compared and discussed based on the 3-RPR manipulator.

Haptic devices become widespread in education and training. Learning to handwrite for visually impaired people is a difficult task. Using assistive haptic device during handwriting learning for people having a visual impairment is the objective of this work. They don’t need anyone to help them in this process. By giving speech command, they can make the mechanism draw the number between any 0–9. Convolutional Neural Network (CNN) is used for speech recognition. Speech recognition for this study is limited only in numbers (0–9)and “unknown” which may occur due to network’s inability or given speech command except for a trained number. This paper focuses on dynamic analysis and control of 5R mechanism by using deep learning for speech recognition.

This paper presents a complete mechatronic approach in design and development of a mobile robot equipped with perception systems for autonomous navigation. The mechanical design, system and control architecture are presented in detail, followed by a description of the locomotion mechanism and the sensory system of the mobile robot. The developed robot has two degrees of freedom (DOF), eight revolute joints (8R) with parallel leg structure using 3D printed parts, commercially available embedded microcontrollers and sensors. The autonomous robotic system was controlled and managed by ROS packages. The experimental results are presented to validate robot functionalities.

Flatness-based feedforward trajectory control is experimentally validated for a crane manipulator that suspends a flexible metal sheet by four chain hoists each positioned by an overhead crane gear. For a desired spatial trajectory of the sheet the control inputs of the individual drives are calculated by an inverse dynamics model that takes the load sway dynamics, an approximated dynamic transfer behaviour of the controlled drive axes and the stiffness of the payload into account. A forward kinematics measurement model enables an estimation of the actual pose of the platform from measured drive positions and chain inclinations. Experimental results show the effect of the control concept.

The aim of the paper is to provide information about a simulated model creation of the shedding mechanism of an air-jet weaving machine. The loom is meant for production of leno weave fabrics. The loom is characterized with the system of the adaptive change of beating-up and shed mechanisms function with picking angle maximization, direct drive of mechanisms and energy recuperation. The possibilities of modern commercial software systems are used to create a computational model of the mentioned mechanism. The main subject of the computations is the estimation of the dynamic properties and behavior of the shedding mechanism, including its drive and control structure.

This work focuses on the dynamic modelling and motion control scheme of a parallel manipulator which has three legs of prismatic-revolute-revolute-revolute joint setup. In each of the legs, the prismatic (P)-joint is active and the rotary (R)-joints are passive. The three legs further join into an end-effector in a right-angled triangle shape. The Euler-Lagrangian approach is followed to achieve the dynamics of the manipulator. The formulations are detailed and simulated. This paper also presents an augmented proportional-derivative (PD) controller along with gravity compensation for the motion control. This control method transforms the closed-loop dynamics of the manipulator into decoupled, and thus it becomes easier to quantify the motion performance. The trajectory tracking performance and its accompanying errors are also discussed.

This paper addresses the numerical and experimental validation of a finger exoskeleton exercising device. The exoskeleton device is analyzed from a kinematic and dynamic viewpoint. Experimental tests are carried out with different users to demonstrate the adaptability and effectiveness of the proposed device in finger exercising and motor rehabilitation tasks.

This paper presents a system developed by the authors that makes use of a new trend in rehabilitation, serious gaming. Short introduction and state of the art is presented in the first part of the paper, after which the main design steps are given and explained. Finally, the testing of the prototype as well as the lesson learnt from building it are discussed in the last part of the paper. The aim of the research was to create an equipment that might be further developed into a fully-fledged rehabilitation device that uses the serious gaming paradigm.

The paper presents a Virtual Reality application (VR) related to a robotic assisted lower limb rehabilitation system. The considered robotic system is dedicated to the patient by performing rehabilitation exercises, that vary in terms of amplitude and duration. The patient performance is measured and the progress registered. The patient received instructions are via a VR headset. The robotic system assists a set of pre-defined exercises in parallel with a real-time control of the motion parameters. The VR exercises are reproduced within in Unity environment. The robotic structure is also represented in the VR together with the patient avatar, in order to suggest the type of exercises that must be practiced.

The article describes the structure of the lower limb rehabilitation system based on serial RRRR mechanism as a passive orthosis and an active parallel 3-PRRR mechanism. A mathematical model of the kinematics of the RRRR mechanism is presented. A description of a numerical method for determining the workspace of the RRRR mechanism based on the approximation of solutions of nonlinear inequalities systems to provide the required rotation angles in joints for rehabilitation is considered. A calculation algorithm, a software, and a visualization system for export the three-dimensional workspaces in STL format are synthesized. The results of mathematical modeling and analysis of the results are presented.

The first objective of this paper is to study the influence of a prosthesis on the maximum values of contact stresses developed in the components of the virtual model of a prosthetic knee assembly, using Finite element analysis (FEA). The second objective is to estimate Lyapunov exponents (LEs) in order to quantify the local dynamic stability of the human knee joint during walking overground for healthy subjects and for patients suffering of osteoarthritic knee (OAK), before and after total knee replacement (TKR), using tools of dynamics stability analysis. The values of the LEs are obtained based on the experimental time series of the flexion-extension movements in sagittal plane and the rotational movements in frontal plane for both knees, collected from a sample of healthy subjects and a sample of patients suffering by OAK before and after TKR. The influence of prosthesis mounted in OAK is positive, the values of LEs obtained for OAK four month after TKR are associated with increased stability, being smaller than those computed for OAK before TKR, and closer than those obtained for healthy knees.

Stroke is a serious disabling affecting care problem worldwide. Unfortunately, the incidence of stroke is increasing which causes a growing demand for alternatives, mainly robotic assisted solutions. The major benefit of using robotic technologies in post stroke rehabilitation process is the ability to deliver high intensity customized training which improves motor and locomotor function. This paper focuses on lower limb rehabilitation and presents a parallel kinematic robot used for the hip, knee and ankle joints rehabilitation. For the developed robotic system, a dimensional analysis and synthesis of the robotic key components with the increase adaptability to different anthropometric characteristics as well as the mirroring of the system’s workspace with the lower limb operational space is presented.

We study a model for a multiple-needle robot based on the Fibonacci sequence scaling. The paper determines the collision-free trajectories of the robot who is carrying drugs into a tumoral target. The purpose of the paper is to predict the insertion trajectories for all needles so as the trajectories should avoid the collisions to ribs, blood vessels and tissues in the abdominal area, the interference between trajectories and finally, to reach the target. Comparison with genetic algorithm and the particle swarm optimization algorithm are performed.

This paper deals with the joint space and workspace analysis of a two degree of freedom spherical parallel mechanism designed to be used to handle an endoscope. This mechanism is composed of the three legs (2USP-U) to connect the base to a moving platform. As the manipulator can get up to six solutions to the direct kinematic problem (DKP) in four aspects, non-singular assembly modes changing trajectories may exist. The aim of the paper is to check whether a regular workspace centred on home pose can be defined in such a way that no such trajectory exists in this workspace.

The paper presents the kinematic analysis of two medical instruments to be used in a robotic system designed for the minimally invasive treatment of non-resectable liver tumors. The instruments will be attached to a parallel robotic system having two modules, one for guiding each instrument. The first one targets the multiple needle insertion for brachytherapy procedures, while the other one is used for guiding a intra-operatory ultrasound probe used for the visual control of the trajectory of the brachytherapy needles. The paper analyses the constraint equations of the two robotic instruments and their integration into the robotic system, using an algebraic method based on the Study parameters of the special Euclidean transformation Lie group SE(3).

Using different imaging techniques (primarily, magnetic resonance imaging or MRI) as guidance in robotic-assisted brain surgery becomes more and more wide-spread. One of important issues in this area is using these imaging technologies in online mode. For that, robotic devices that are compatible with MRI systems are required. In particular, conventional electric drives are not suitable; some alternatives should be used, such as piezoelectric drives (PED). In this paper, a robotic system is described intended to deliver a needle (cannula) to a given point by means of a PED. Dependence of the driving force generated by PED upon the needle speed is studied. In order to describe the contact interaction between the cannula and the soft tissue, a mathematical model of their interaction is developed based on modified Kelvin-Voigt approach. A phantom of porcine brain is manufactured. Experiments are carried out where the cannula was indented into the phantom. Based on the obtained experimental data, parameters of the mathematical model are identified. Numerical simulation of the insertion of the cannula into the soft tissue is performed, and the effect of parameters of the feedback control loop upon the cannula dynamics is analysed.

Introduction: Robot-assisted liver tumor ablation has emerged as a new minimally invasive therapeutic strategy for hepatocellular carcinoma, as well as colorectal metastases with higher accuracy, in a smaller time span and with a lower radiation dose than in the manual approach. Several ablation methods count, mostly used are radiofrequency ablation, microwave ablation and cryoablation. Materials and methods: The specialty literature was surveyed in order to retrieve manuscripts reporting “robot-assisted”, “liver tumor”, “ablation”. The search strategy was applied in three different databases, Scopus, Web of Science and Embase. Fifteen original articles were selected and seven were excluded from the study, in order to compare results of robotic ablation for liver tumors both on patient series or on experimental models. Results: Out of a total of fifteen articles included in the study, six articles focused on the clinical aspect of robotic liver tumor aspect, providing patients description and characteristics on a total of 172 subjects. There were nine studies, which focused on the technical assessment of the robot during ablation on experimental model. The indications for percutaneous ablation usually include malignant tumors, hepatocellular carcinoma (55 tumors) or colorectal liver metastases (92 tumors) for lesions smaller than 3 cm in diameter, which cannot benefit from liver resection. The most commonly reported type of ablation was microwave technique (43%), followed by radiofrequency (40%). Only one article evaluated laser ablation effects and another one reported irreversible electroporation. The number of needles used for ablation according to the tumor volume varied from 1 in 50% of cases to 5 and the number of needle readjustments reached 1 to 14. The type of robot used was different in the fifteen studies. Conclusions: Development of more versatile robots and intuitive software that will reduce the total time of the procedures is highly expected, thus transforming imaging guided robotic ablation into the golden standard procedure for inoperable primary hepatic tumors or liver metastases.

Hepatocellular Carcinoma (HCC) is the most frequent form of liver cancer, being the fourth leading cause of cancer-related death worldwide. The curative treatment in most cases is the tumor removal from the body (surgery), but more than 70% of HCC patients have advanced tumors and cannot be treated with such procedures. Alternative laparoscopic surgical treatments, such as high dosage radiation-brachytherapy (HDR-BT) or inside-tumor drug release (IDR), are currently researching for tumor size reduction. Our target is to develop computerized methods for assisting the medical robot used in such treatments, to make them safer and more efficient. We build an accurate 3D model of the HCC anatomical context, based on Computed Tomography (CT) images acquired before surgery, putting into evidence the HCC tumor, its position within the liver and the most important blood vessels connected to it. We also highlight, in real time, during surgery, the 2D slice corresponding to the transducer position. In this article, we describe the corresponding software system, focusing on the segmentation and 3D reconstruction techniques, assessed through specific experiments.

A simple, analytical model for load sharing and quasi-static transmission error of spur gears with non-standard tooth height is presented. It is based on the minimum elastic potential energy principium and considers the influence of profile modifications and tooth deflections. In addition, is suitable for different tooth height on pinion and wheel, as well as for standard and high-contact-ratio spur pairs.

This paper proposes a quasi-static model with 12 degree-of-freedom (DOF) for the transmission error (TE) analysis of a single-pair of herringbone gear drive. In this model, the manufacturing errors of the gear set are considered, such as the asymmetric error of the double helical line in the pitch cylinder, tooth profile error and circular pitch accumulated error at the transverse plane, which is converted to the common normal direction of the gear pair. To calculate the clearance between the gear pair, the piecewise discrete method is adopted, the meshing of the herringbone gear set, then, can be regarded as that of a series of slice-units. The kinematic relationship between each of the slices and the gear pair is established by equilibrium equations and complimentary equations. Thus, the TE of a herringbone gear drive can be simulated. The influences of various errors on the TE of a herringbone gear set are analysed, to show the proposed method feasible and effective.

Based on the theory regarding algebraic equation of higher degree, a method to compute the meshing limit line for a conical worm drive is brought forward. No iteration is needed to perform this method so the corresponding computer program can be simpler. By employing this method, it is mathematically proved that the meshing limit line does not exist on the internal flank of a conical worm tooth and two meshing limit lines exist on the external flank of the tooth. The numerical results illustrate that the two meshing limit lines on the external flank generally are all outside of the practical tooth surface of the worm and the practical tooth surface is on the useful side of the meshing limit line. This signifies that the working length of a conical worm may fully cover its whole thread length at least theoretically. At the toe of a conical worm, the meshing limit line is nearest to the tooth surface of the worm, and the risk that the meshing limit line enters into the worm tooth surface is the most at that position.

Each different sensor technology has advantages and disadvantages in pursuit of detection and diagnostic before a catastrophic failure in condition monitoring. Acoustic emission (AE) records the high frequency waves generated by diverse physical sources, employing a piezoelectric sensor. These AE perturbations are produced in the interaction of the gears and other components such as bearings. The asperity contact between surfaces is a fundamental source of AE waves. The good sensitivity of such sensor to any behavior variation of the contacts leads AE to its application in the monitoring of surface damage. This paper investigates the surface damage progression in one gear of a planetary transmission by AE monitoring. One pinion is subjected to a natural but accelerated wearing, thanks to the lack of teeth surface treatment. The evolution of this gear and its influence in the acquired AE signals, centered on the AE event width, are used to analyze the response and potential benefits of this technique in the condition monitoring of planetary gearboxes.

This work focuses on the impact of different kind of errors into planetary transmissions performance. These errors involve position errors, both tangential and radial, and tooth thickness errors. From a quasi-static point of view, the incidence of those errors is analysed and how they affect the load sharing of the transmission. At the same time, the load sharing is affected by the geometrical configuration of the transmission, so a study of the influence of the mentioned errors given those geometrical differences is performed. Besides, the interaction between errors is analysed for planetary transmissions given the torque and the rotating sense for every geometrical configuration considered.

The paper gives a new method for obtaining the specific sliding coefficients for involute spur gears. While sliding coefficients are determined in the technical literature using differential geometry, this paper if using a kinematical method to achieve the same result. Based on the equalization conditions of the specific sliding coefficients at the points where the meshing begins (A) and ends (E) the profile shifting coefficients can be computed in order to design gears with their geometrical dimensions optimised for a longer lifetime.

This paper studies the effect of wear that occurs in the contact between pin and bushing in revolute joints with clearances due to manufacturing tolerances, and the evolution of the size and shape of the free spaces with the work cycles. The objective is to propose an efficient method to estimate, during the design procedures of a machine or mechanism, the variation of the clearance and its shape. Ease of analysis and efficiency is prioritized over accuracy, which anyway must be kept within admissible levels. In order to streamline the application of the method to any multibody system, SolidWorks has been used for design and multibody simulations, and Excel for calculation of the wear suffered by the joints.

The modeling of parallel kinematic machines (PKM) has been a topic of ongoing research since PKM started to gain popularity more than twenty years ago. Due to the modular setup of most PKM, research has been conducted towards modular modeling paradigms. This applies in particular to so-called fully parallel PKM. Recently, a general modeling approach was introduced for such PKM, which rests on a Lie group formulation of the kinematics and dynamics. Therein, the PKM kinematics is described by means of screw coordinates, which makes this a user-friendly approach free from restrictive modeling conventions. In this paper, application of the method is demonstrated for a simple planar 3RPR PKM.

The paper illustrates the occurrence of chaos phenomenon when dynamic modelling of a mechanical system is performed. The equations of motion of a 2DOF physical planar pendulum are obtained and subsequently they are numerically integrated. The same system is also modelled using dedicated software. The numerical results and the ones given by the software coincide only for a short duration after launching. The paper highlights the strong dependence of the evolution of the system upon the initial conditions, confirming the existence of the chaos phenomenon. It is also revealed the connection between the accuracy of the initial conditions and the dimension of the corresponding interval.

The subject of this paper is the elastodynamics of a novel three-limb, full-mobility parallel-kinematics machine (PKM) with flexible links, intended for high-frequency, small-amplitude operations. By modeling the light-weight limb-rods as identical linearly elastic beams, the flexibility of the in-house developed SDelta robot is taken into account. The PKM is modeled as a six-dof Cartesian mass-spring undamped system. The Cartesian stiffness and mass matrices are derived based on the virtual-joint model. The elastodynamics performance of the SDelta prototype at the desktop scale is numerically evaluated. The calculation results shows that the prototype has the ability to operate at a frequency below 30 Hz with a 5-kg payload.

In the design process of a mechanism, the dynamic behavior plays an important role. It could be the cause of unexpected high dynamic forces in later stages when it is not considered in the early stage of the design process. High forces could produce high stresses and high vibration levels. Several studies have been carried out in this area; however, only a few consider structural criteria and the eigenfrequencies in the early stage of the process. Low forces and an adequate structure should lead to good dynamic behavior. In this work, we present a method to synthesize function generator four-bar linkages that takes into account structural criteria in a joint-forces minimization-maximization problem. Its objective function is the reaction force on the mechanism joints. The problem’s constraints are the maximum stress on the links, the first eigenfrequency of the mechanism and the deflection of the crank and the rocker. With this method, the links’ lengths and cross-sectional areas of the mechanism are obtained for a given task. As condition, we assumed that the crank rotates with constant angular speed and its shaft works as a torsional spring. Moreover, the rocker moves a body with constant inertia. The resultant mechanisms are compared with those obtained with a traditional crank-rocker synthesis method, according to VDI 2130. To compare both methods, the maximum force, maximum stress, deviation of the rocker angle at its dead-center positions and RMS vibration of the crank and rocker of each mechanism are calculated using MSC ADAMS™. The results show that the mechanisms obtained with our method have better stress and vibratory levels than those obtained with a traditional approach.

Hydraulic steering systems are used in construction and agricultural vehicles with high steering loads. Integration of advanced functionalities like driver-assistance systems and increased safety regulations requires the development of new steering system concepts like steer-by-wire systems. Hardware-in-the-loop (HiL) testing of physical steering systems in bidirectional interaction with a numerical vehicle model enables reproducible, safe and cost-efficient experimental analyses under various nominal and failure operating conditions in a laboratory environment. The present contribution describes the parametrization of a multibody vehicle model of an agricultural tractor based on measurements from driving tests and its integration into a HiL test bench for hydraulic steering systems. First results show the functionality of the HiL concept.

This article presents a graphical analysis method for the verification of the gravity force balance and shaking force and shaking moment balance of a 1-DoF pantographic linkage. First the joint velocities of the linkage are graphically found of which the procedure is well known. To obtain the linear and angular momentum graphically, the mass and inertia of each element are modeled with two equivalent masses about the center of mass of the element, resulting in a mass and inertia equivalent model with solely point masses. The velocities of these point masses are obtained and each velocity vector is multiplied with the respective mass value to obtain vectors that represent the linear momentum. For force balance it is shown that the sum of all linear momentum vectors form a polygon. Subsequently the linear momentum vectors with their moment arms are transferred into an angular momentum diagram which for moment balance shows to sum up to zero.

The paper presents the inverse dynamics of a medical parallel robot used for shoulder rehabilitation, namely ASPIRE robot. Using the robot inverse kinematics, the inverse dynamic model of ASPIRE is obtained in a closed form using the principle of virtual work associated with the equivalent dynamic lump masses of the experimental model. In addition, Siemens NX is used to perform the kinematic and dynamic simulation for the parallel robot. The simulation results are compared to those derived from the theoretic inverse dynamic model and the comparison shows the validity of the mathematical model.

Human walking has been intensely studied, but it is difficult to reproduce on humanoid robots that maintain awkward movements. Three main difficulties exist. (i) Different joint kinematics and size between humans and robots. (ii) A rolling motion of the foot which is often impossible to execute with humanoid robots that walk with their feet flat. (iii) A difference in the dynamic model of a robot compared to a human that makes a copy of a human movement lead to unstable walking. In order to take into account the first two difficulties, the specifications for reproducing human movements are adjusted. To ensure stability, a previously developed dynamic model called Essential Model is used. The zero moment point (ZMP) is imposed, and the horizontal evolution of the centre of mass (CoM) is computed to satisfy the ZMP.

Engine start quality and seamless engine start/stop are key elements of drive quality and customer acceptance in today’s electrified propulsion architectures. Two novel mechatronic devices have been created for premium engine start/stop. One concept uses a motor/generator in place of the traditional alternator, coupled to a mechatronic switching device for selectable geared or belted operation of the motor/generator. The second starter concept uses a two-speed gear scheme inserted between the starter motor and crankshaft flywheel for smooth engine starts. In the present work, the use of these starter devices in vehicles with sailing/coasting mode as well as in mild hybrid propulsion systems is described. Sailing/coasting mode of operation is enabled by the quick engine re-start capability of these starters allowing seamless switching between fuelled and unfuelled engine operation. This could reduce fuel consumption by about 3–6% on the NEDC driving cycle, without regenerative braking. One may further hybridize the propulsion system by adding a battery for storing regenerative braking energy. Using such an architecture, a 6–8% fuel economy improvement on the WLTP certification driving cycle may be achieved, depending on voltage and power levels implemented, as well as energy storage systems included.

Robot Operating System (ROS) is widespreading framework allowing researchers to create functional control environments for robotic systems. But one of the main problems connected with ROS installation is its distribution actually snapped almost explicitly to Debian/Ubuntu Linux and their package bases for x86 and ARM architectures. If the embedded proprietary platform is required to be used for creation of the robot (e.a. to work with non-standard hardware interfaces), ROS installation becomes non-trivial task. In this case it requires to build all ROS modules from sources and to integrate the obtained binaries into control system manually. This paper discusses the case of ROS installed and integrated into high-reliable general purpose industrial control platform based on proprietary hardware equipped with Elbrus VLIW (VLIW (Very Long Instruction Word)—CPU architecture that allows to embed set of operations into single machine instruction for assembly-level parallelization) CPU. The advantages of embedded ROS installation, peculiarities of its integration into a robot and licensing issues are also described.

Variable stiffness actuators (VSAs) have been used in many applications of physical human-robot interfaces (pHRI). A commonly employed design is the spring-based VSA allowing the user to regulate the output force mechanically. The main design criteria of these actuation systems are the adjustment of output force independent from the output motion, and shock absorbing. In our recent work, we implemented certain modifications on the two-cone friction drive continuously variable transmission system (CVT) so that the CVT can be employed in pHRI systems. Subsequently, the optimized prototype is developed. In this study, we introduce the prototype of this new CVT systems, and its force calibration tests. The results indicate that the manufactured CVT is capable of displaying the desired output force throughout its transmission ratio range within a tolerance.

This paper compares possibility for the spacecraft equipped with liquid-fuelled rocket engine to change orbital plane for purposes of space debris collection. The simple method of orbital plane rotation angle calculation is described. Also recommendations for fuel components selection made using possible orbital plane rotation angle as the main factor.

Innovative steering systems require extensive testing procedures before they are ready for on-road use. Safety, durability and comfort aspects have to be proven before mass production even starts. This processes can take high amounts of test drives on specially equipped prototype vehicles, which is expensive, difficult to reproduce and sometimes even dangerous. To enhance all aspects of the testing process, a hardware-in-the-loop (HiL) test bench for hydraulic steering systems is developed at the University of Rostock, which will be used to emulate several vehicle parameters, driving maneuvers and system failures of the steering system.As an answer to component modularity of steering systems, this HiL test bench is designed to keep up with fast test environment modification without any effort. Therefore, the interfaces between the steering system and the vehicle reactions are determined in the hydraulic system, instead of the steering mechanics. This makes it possible to reduce the amount of mechanical steering components, such as the respective steering axle, on the test bench and emulate their characteristics in the vehicle model, to start testing even in the development state.

This work presents a general formulation to identify the contact points for the interaction between wheels and rails in the context of railway dynamics simulations. This formulation treats the wheel and rail as parametric surfaces and searches the contact between each wheel strip and the rail independently to avoid the numerical difficulties due to the wheel concave zone. This methodology assumes the rail as locally straight and takes advantage that its potential contacting surface is always convex. For the evaluation of contact forces, two Hertzian-based models are employed for normal and creep forces. A trailer vehicle running on a curved track is used to demonstrate the effectiveness of this methodology.

The mathematical model of a small-scale counter-rotating Savonius wind turbine is constructed and studied. Rotors are located one above the other. Their shafts are coaxial. The shaft of one Savonius rotor carries the rotor of an electric generator, and the shaft of the other carries the stator of the same generator. Savonius rotors are supposed to rotate in opposite directions. Thus, the relative angular speed of the generator rotor with respect to the stator is increased. The generator is connected to the local electrical circuit. Operation modes corresponding to autorotations of Savonius rotors in the wind flow are discussed. The trapped power in such regimes is estimated. It is shown that the chosen design of the wind turbine is characterized by the same maximum power coefficient as a classical single Savonius rotor, but with double increase of the relative angular speed of the generator rotor with respect to the stator. Parameters of the system that provide maximum trapped power coefficient are found.

A key advantage of cable-driven parallel robots, compared to other robot types, is their large workspace. Despite this fact, experiments in previous works have shown that cable-driven parallel robots often cannot fully realize their theoretically estimated workspace in practice.To remedy this shortcoming, a new inverse kinematic code is developed which considers the previously neglected effects of both cable sagging and pulleys. For a realistic exemplary robot, the new kinematic code yields a $$19.5\%$$ larger wrench-feasible workspace volume for the catenary-pulley model than previous codes. This result shows that the effects of cable sagging and pulleys should be considered in the kinematic codes, especially for large cable-driven parallel robots.

Stroke is a high incidence disease which affects over 1 million people per year only in Europe. In the last years the post-stroke survival rate has increased a lot but still more than 70% of the survivors experience a certain level of motion impairment. This paper focuses on the necessity and advantages of introducing technologies in the field of post-stroke rehabilitation, and more specifically on introducing a cable-driven solution into the field, emphasizing their control system, design, motion particularities and experimental tests demonstrating the effect that cable structures have on maintaining a predefined trajectory despite deviations that may occur due to the patient’s lack of control.

Cable-Driven Parallel Robots (CDPRs) have been little used so far for collaborative tasks with humans. One reason is the lack of solutions to guarantee the safety of the operators in case of failure. Therefore, this paper aims to determine the possible failures of CDPRs when they are used for collaborative work with humans and to provide technical solutions to ensure the safety of the operators. A translational three degrees-of-freedom CDPR composed of four cables connected to a point-mass end-effector is considered as an illustrative example. The cables are supposed to be ideal, namely, they are not elastic and do not exhibit sagging.

The selection and design of the kinematic diagram of the mechanism is the first stage in the creation of a technical device. In the design process, an optimization task inevitably arises, during the solution of which it is necessary to choose the best one from the proposed options according to certain criteria. This article proposes a software solution to automate this process. On the example of the synthesis of a planar mechanism by a given function of the output joint, the advantages of this automated approach are shown. When solving, the two methods are used: enumerating various geometric parameters for a given structural diagram of the mechanism and solving the forward kinematic problem, followed by finding the minimum of the target function, as well as solving the inverse kinematic problem for a given structural diagram of the mechanism.

This paper compares the static performances of two types of antagonistically actuated joints: a revolute (R) joint and an antiparallelogram (X) joint. Both joints are equipped with lateral springs and actuated with two opposite cables running through the springs. The comparative study is conducted on the basis of their wrench-feasible workspace and stiffness. A methodology is proposed for the optimal design of each joint. Eventually, an R-joint and an X-joint, optimized for the same prescribed wrench-feasible workspace, are compared on the basis of their maximal actuation forces.

In this paper compliant multistable tensegrity structures with discrete variable stiffness are investigated. The different stiffness states result from the different prestress states of these structures corresponding to the equilibrium configurations. Three planar tensegrity mechanisms with two stable equilibrium configurations are considered exemplarily. The overall stiffness of these structures is characterized by investigations with regard to their geometric nonlinear static behavior. Dynamical analyses show the possibility of the change between the equilibrium configurations and enable the derivation of suitable actuation strategies.

The paper analyzes the experimental analysis of a multibody system (MBS) having 2 DOF. The mechanism belongs to a water turbine pump, commonly used in small farms. The accelerations of different points of the mechanism are optically measured so that they can be used within the dynamic model with finite elements and, finally, the eigenpulsations of the system are determined. The obtained results are tested using an experimental bench.

In soft robotics, the successful development of soft robots involves careful designing that can benefit from current technologies. The use of Finite Element Method (FEM) software and additive manufacturing is essential to optimize the design before fabrication and to facilitate the process. Therefore, we present the design of a 3D printed low-pressure soft pneumatic actuator (SPA) with 3 DoF and a material characterization method to simulate the behaviour of the system. In attempt to define a suitable material modelling method and its reliability to simulate actuator behaviours, we introduce a characterization method and corroborate its efficiency through the evaluation of the performance using the FEM and preliminary tests of the actuator performance. The purpose of this article is to help future projects to effectively simulate the behaviour of 3D printed soft pneumatic actuators to improve the design before fabrication. Throughout the description of the process to effectively fabricate a functional SPA.

The paper deals with a second version of kinematic chain of the geared linkages with linear actuator using a slider crank base mechanism. This structure is recommended because geared linkage with linear actuation allows a large rotation angle with approximately linear transmission function in a large range and proper transmission angle. These characteristics and the direct actuation of the closest element to the mobile platform ensure the avoiding of the first order singularities.

Changes carried out by the European Higher Education Area have allowed to design and develop new learning methodologies that focus on students as an active part of the education process. This allows to develop not only technical skills, but also the so-called soft skills. In addition, sustainability has become a key issue in recent years, being Education an important part of it. In this context, a novel educational project, Formula Student Bizkaia, has been proposed as an innovative way to address education in engineering that combines both student-centred learning and sustainability. In this work, the project structure, its motivation and foundations, and its alignment with the UN 2030 Sustainable Development agenda is detailed.

The aim of this study is to use within the teaching methodologies the ADAMS software for determining the mobility of the overconstrained mechanisms. Computer-assisted learning helps students to understand and calculate the parameters needed to apply the general structural formula for determining the mobility of overconstrained mechanisms. The paper presents a computerized procedure for determining mobility for mechanisms with one or more independent cycles, with the independent/dependent movements of the end-effector of the kinematic chain associated to a loop.

This paper presents an analysis of the mechanism found in the clock tower of the Petrovaradin Fortress in Novi Sad. The clock mechanism dates back to the beginning of the XVIII century and thus has great historical value. It consists of three interconnected mechanisms – the timing mechanism that keeps time and powers the clock hands, the quarter striking mechanism that sounds the quarter-hours and the full hour striking mechanism that sounds the full hours.