New Advances in Mechanisms, Mechanical Transmissions and Robotics

The paper shows the optimal synthesis of grasping device design based on the Chebyshev spacing method. The original grasping device uses two symmetrical four-bar linkages with opposite motion of the jaws fixed on the coupler. The goal of the study is the development of a grasping device with minimal error of the axial centering, which reduces the synthesis to a four-pose one for the four-bar linkage. In order to minimize the centering error of the grasping device an equivalent Chebyshev spacing method for establishing the synthesis poses is used. A simplified pose synthesis method for the grasping four-bar linkage is developed. The both deviations of the axial centering errors (without spacing and with spacing) for the obtained linkage are indicated and analyzed.

The aim of the paper is presentation of the modified method of utilization of the contour graphs for an analysis of kinematics of the closed crane mechanisms. An introductory phase of calculations is necessary for performance of further dynamical analysis of the mechanisms because—in the considered duty cycle—the linkages of the mechanisms are subjected to a non-stationary motion. The non-stationary motion mode is characteristic for a startup and a braking as well as during an unstable motion of the system. The results of calculations: velocities and accelerations for particular linkages of the mechanism are shown in various figures mainly as a function of the rotational angle of the drive linkage.

Extending Assur’s kinematic chain (AKC) principle of the planar mechanisms to space parallel mechanisms, this paper studies the composition principle based on the space Assur’s kinematic chain (SAKC) as well as the type synthesis method based on SAKCs for the parallel mechanisms (PM). First of all, a new expression for the PM composition based on SAKC is proposed, which has clearer physical meaning; Secondly, according to the principle of composition and the formula for calculating the value of the coupling degree k, 53 types of SAKCs with coupling degree k = 0–3 and the basic loop v = 1–5, as well as their analytical expressions, are presented. Also it is found that these SAKCs can express 40 types of SAKC structures which are the basic unit of PMs. Finally, a general and practical method for type design of PM is presented regarding SAKCs as the composition units and meeting the position and orientation characteristics (POC) set as the design goal. One example is illustrated.

An alternative faster method for cam mechanism displacement parameters analysis based on image processing and Artificial Neural Network (ANN) is proposed. The method is developed in Matlab and consists of a Graphical User Interface that displays the cam-follower position, velocity, acceleration and jerk diagrams (svaj) versus the angle of rotation of the cam. These diagrams are generated for four types of cams based on a preliminary elevation curves of the cam-follower obtained with help of GL 112 cam analysis apparatus. The method reduces the time for calculating the parameters and the results can be compared with the ones from analytical method. The image processing algorithm considered is based on a set of images taken with a HD camera of the investigated cams. These images are further processed in order to train an ANN which it finally conducts to automatically identifying the cams.

The paper deals with the kinematic analysis of a particular case of a “multiple-bar mechanism” from Artobolevsky’s mechanisms collection. The structural analysis of this eight-link mechanism shows that it is a six class third order mechanism according to Assur-Artobolevsky classification. The kinematic analysis of such a mechanism is very difficult through the direct method. Usually, the kinematic analysis is performed by means of reducing the mechanism’s class through the swapping of the input and output links. The paper proposes another method to reduce the class of a mechanism, namely by choosing a certain moving link as referential and studying the relative movements of the remaining links/elements. Thus, the transmission function can be found, as a function of the original input and output links. Such a mechanism is useful for manufacturing of compound light structures.

The static balancing of the weight forces is necessary to any mechanical system which is not working in horizontal plane. The effect is the decreasing of the acting power. From practical point of view two main passive ways of static balancing could be taken into consideration: by mass redistribution of components or/and by adding counterweights, and by elastic forces of the springs or of the gases. The first solution is not always possible due to the dimensions of mechanical systems and due to increasing of the dynamic stresses of components. Second solution is more and more used to various mechanical systems. The complexity of balancing systems with springs comes from the need of using zero-free-length springs. Instead of using complex balancing systems with real springs, some zero-free-length elastic systems are proposed. Present paper is continuing former papers of authors and is presenting some new constructive solutions of zero-free-length elastic systems. Finally an example is solved.

Because spline joints transmit torque from shafts to rotors by multiple contact surfaces, the joint’s mechanical system is undetermined, thus, the actual load distribution is greatly influenced by the joint’s elements elastic properties. In previous works, an analytical method using differential equations of 2nd order to determine load distribution on joints’ length was proposed. In this paper, a comparison between analytical and experimental study results for the load distribution on the length of joints under pure torque is presented.

The behaviour of the kinematic chain R(RPRGR)RR using geared linkages with linear actuation recommends to be used as connection kinematic chain (RPRGR) for the parallel manipulators. The paper proposes a dimensional synthesis method for the planar parallel manipulator using geared linkages with linear actuation. It computes the minimum link lengths of the connection chain by considering the condition to avoid the desired trajectory intersection with the singularities loci in the achieved workspace. The synthesis results were analysed by means of inverse kinematic analysis.

In pick and place operations a mechanism moves an object from an initial to a final pose and repeats, with frequencies of operation that can achieve 150 picks per minute. The paper presents the concept of natural motion for this kind of operations, where the basic idea is to add elastic elements to the mechanism and try to match the desired motion with the natural motion of the system. This concept was implemented in a multibody simulation of a five-bar linkage by using numerical optimization to find the required spring constants as well as the trajectory that minimize the torque on the motors. The required energy of the system using the concept of natural motion was compared with that of a typical trajectory, finding that the use of springs and natural motion reduces the energy consumption by 68 % per cycle.

Geared linkage structure is defined in literature considering the type of linkage, usually four-bar or five-bar, and different versions are obtained by changing the input/output, the fixed link and the gears connections with linkage links. The paper proposes the structural synthesis of the planar geared linkage mechanisms with one pair of gears, as multibody systems with four bodies. The algorithm derived from the structural synthesis of the linkages as multibody systems with four bodies lead to eight distinct general kinematic chains, from which two contain a rigid sub-chain and, from the other six, only four contain the sub-chain formed by three bodies with five kinematic constraints. Replacing these sub-chains by the gearing sub-chain, seven variants of distinct kinematic chains with 1 DOF for geared linkages are identified (four general and three particular). Based on these, 27 distinct geared linkage mechanisms were obtained. This approach allowed to identify already known mechanisms but also new ones.

This study proposes to use the non-linear properties of the support bearing viscoelastic material for damping of resonance oscillations of a vertical unbalanced gyroscopic rotor. To this end, it analyzes in detail the impact of non-linear damping and non-linear elastic characteristics of the support bearing material on the resonance curve and vibration stability. The options of nonlinear quadratic and cubic stiffness of the material are considered. If a cubic nonlinear stiffness influences the transmissibility to much higher resonance regions, on the contrary a quadratic nonlinear stiffness influences the transmissibility to much lesser resonance regions. Under the influence of the nonlinear damping and nonlinear elastic characteristics of support bearing not only the resonance amplitude of oscillations greatly decreases, but also the boundaries of the instability region are moved down, and its width reduces significantly. The results are of significant importance in the analysis and design of nonlinear passive vibration isolators.

For a Hindley worm, the addendum thickness of its edge tooth intensely affects its working performance and the manufacturability of its mating worm gear, whose computation is thus taken into consideration. The analytical solution to the addendum thickness is obtained for the edge tooth. The numerical results declare that the TA worm has a stronger resisting ability to the pointing of its edge tooth. Even though the number of worm thread is more or the velocity ratio is less, the edge tooth is also able to be kept thick enough. The further related research should focus on the influence of the modification on the pointing of the edge tooth.

The subject of research is a planetary train with two planetary rows and two carriers. The plot of linear speeds of the mechanism with two carriers shows an unexpected phenomenon: each carrier has direct kinematic constraint with satellite of opposite row. The interacting point of satellite with the carrier can be presented in the form of an engagement of the additional wheels connected to the satellite and to the carrier. Additional constraint creates brand new phenomena in the theory of mechanisms and machines. Paper presents the analysis of a phenomenon of additional constraint in the planetary train.

This paper presents an approach for modelling and simulating of harvester head mechanism in the harvesting process of hardwood stands. This type of trees is characterized by flexuous trunks and big branches. Hence, the current harvester heads are not enough efficient to process such trees. In order to predict the process performances associated with several novel architectures of harvester heads, in preliminary design stage, a modelling of the process has been developed. It is based on parameterized tree models with realistic geometry by adapting an existing method. Dynamic modelling of the delimbing process proposed in this paper uses original cutting and feeding models which have been validated experimentally. The modelling and simulation of harvester head mechanisms have been implemented in a numerical multibody environment. Simulation results of the global model are in a good agreement with the observed behaviour of the real system.

The speed increasers are typical components of a large diversity of renewable energy systems (RES), like wind turbines or hydropower plants, used to harmonize the low input speed of wind rotor/hydro turbine with the higher speed requirement of the electric generator. The counter-rotating turbines are able to generate more electricity in comparison with the classical systems with one input due to the summation of the two independent input speeds and implicitly of two power flows, but they have a relatively complex control for matching the generator requirements. This drawback can be mitigated by using 1 degree of freedom (DOF) speed increasers with more inputs and one output. The paper deals with the kinematic and static analysis of a novel 1DOF planetary transmission, with two inputs and one output, used as speed increaser in wind/hydro RES. Starting from its property of summing two external torques and the speed amplification ratio imposed on the main power flow, the transmitting functions of speeds and torques, considering gear friction, as well as the mechanism efficiency are established in the paper. A dimensionless parameter k, defined as ratio of the input torques, is introduced and, based on numerical simulations, the transmission behaviour is highlighted. The results allow the formulation of useful recommendations for optimal design of planetary transmissions implemented in RES.

In this paper, Melnikov method is employed to detecting the edge of chaos for a micro-cantilever. The difficulties arising from the integrals in Melnikov method are refrained through using MATLAB/Simulink. The edge of chaos plotted on a two parameter plane indicate that the condition of chaos occurrence derived from Melnikov method is compact for some system parameters, but is conservative for the others. Therefore, applying Melnikov method to detecting edge of chaos is far from perfect method.

As part of this paper, a hydraulic excavator analyzed by Hall et al. [7] is studied on both kinematic and kinetostatic points of view by means of a modern approach: the structomatic method. The main steps of this method are explained and highlight its potential for the study of complex mechanisms by decomposing the hydraulic excavator into unique groupings called structomats. These ones allow to solve the closed-loop vectorial equations separately and can be found in any mechanisms, which facilitate the computer-aided implementation of this method due to the fact that the subroutines related to the structomats can be employed to study other mechanisms. The structomatic method is used to compute the kinematic parameters of the bucket’s centroid along with the active force of each of the three actuators depending on their predetermined sequence of motion. The structomatic method is straightforward and systematic for the study of a large amount of mechanisms and acts as an alternative to existing methods.

The paper shows the conception of a cam workbench for educational purposes. The cam workbench aims at sustaining the learned design process and visualizing learned effects. Therefore different cams with typical transfer functions are selectable for both follower types, translating and oscillating. The properties of these cams can be analyzed by students. Besides, kinematical length of the mechanism like eccentricity and the central distance can be varied. So the students can experience the influence of the pressure angle on the complete mechanisms. In addition, the students can calculate and design their own cam. Therefore, they can practice the learned theory in exercises. The designed cams can be manufactured by 3D-printing and plugged on to the different cam shafts.

This paper presents a kinematic characterization of the Origami Spring, which can change its shape from a flat, contracted state to a solid, extended state. Through observation using a real model, the Origami Spring was modelled as a spherical 6R linkage with 3 degrees of freedom (DOF). To obtain a kinematic model, which enables kinematic design of the Origami Spring for real applications, mobility analysis and displacement analysis have been performed. To reveal the actual behavior of the Origami Spring: it behaves like a single DOF, displacement analysis has been formulated as an optimization problem with a single input using objective functions taking into consideration collision between links. Numerical examples were presented to discuss the kinematic characteristics of the Origami Spring.

The paper presents a design concept for a scaled-down test stand that allows studying of various possible anti-lock brake system algorithms, by considering a quarter car model traveling over an uneven road surface (a bumpy road, or a road with continuous variable friction coefficient), represented by a rolling inertial tambour track, in contact with an articulated braking wheel. The concept is transposed in a CAD model simulation where motion analysis can be conducted. Also a software application is designed for generating a road surface profile (for the CAD model) and verifying it against the real motion of a smart servo motor. The combined simulation results prove the viability of the concept and encourage the authors to further develop this scaled test stand.

Participation of scientists from CIS and former USSR countries in development of terminology for Mechanism and Machine Science (MMS) is considered. Identification of notions in the field of MMS as well as in the frame of IFToMM Permanent Commission “Standardization of Terminology for MMS” activity at execution of other programs is analyzed. Analysis is provided for IFToMM Terminology in general, and specifically for the following sections: Gearing, Quality Factors of Machines and their Components. Problems of gear drive types classification and gear failure modes are discussed too.

Separate sections of MMS Terminology are considered. Separate sections from Special Issue “Terminology for the Mechanism and Machine Science” and Electronic Dictionary elaborated on the base of abovementioned Issue analyzed. Some proposals for the next step forward of MMS Terminology made.

For increasing the performances and for a proper working of a robotized flexible manufacturing system (FMS), it is necessary to calibrate the components’ parameters of the relative positions. Also the robotized FMS must be implemented into a complex control system program related to a specific application. The calibration method can be simplified by using design solutions with a common base plate. The uncoupling of the robots’ movements is proposed as simplified method for the calibration of FMS.

The mobility analysis of a 2-URU parallel mechanism (PM) using the screw theory and its novel application for constructing reconfigurable mobile robot are the main focus of this paper. By taking advantage of the singularity positions, the PM can reconfigure into different mobility configurations, which enable the robot to multi-mode collaborative locomotion and cooperative serial-parallel hybrid manipulation. Integrating these properties, a novel reconfigurable rescue robot called Reconbot composed of a track platform, a reconfigurable 2-URU PM with an equal offset in its two universal joints and two 7-DoF serial arms is proposed. The PM consisted of two offset URU branch chains and two platforms serves as dexterous upper body with base platform mounted on the track platform and two arms attached to the moving platform. The Reconbot can deform into folding compact state, serial two-leg state, parallelogram five-bar linkage state, etc.

This paper presents a formulation of the kinematics model of wheeled mobile robot with articulated limbs. In order to describe the contact motion between robot wheels and ground, a differential kinematics model is used. Following the already mentioned, nonholonomic constraints of the wheel no-slip movement are introduced in a form of Pfaffian constraints. Further section of this article describes the kinematics control system preventing wheel slip. To ensure the no-slip motion conditions, null space of a Pffafian constraints matrix is taken into consideration. Finally, numerical simulation is presented as proof of validity for the previously developed and proposed control system.

This paper presents an experimental platform developed for hexapod locomotion analysis and experiments over common types of obstacles. The platform contains two elements: a model of a six legged mobile robot used for real tests on different obstacle categories and a software simulator interface which allows study of the robot stability in gravitational field, assuring in the same time the control of the mobile robot during real experiments. For the hexapod robot this paper presents our design for the leg, its kinematical model and workspace analysis. The control part is a combination between Matlab, a micro-controller based development board and dedicated servomotor controller board. The trajectory generator for the leg tip was implemented using piecewise cubic spline interpolation method. Finally, this paper presents some experiments on spiral stairs for which the locomotion sequences strategies were designed in order to overcome them using the following constrains: maintain the robot’s body parallel with respect to the ground and maintain the maximum height of the robot during locomotion.

In quadcopter design process, usually the selection of rotor and propeller are treated carefully because they will determine the maneuver abilities as well as the speed and maximum carry load. Among various methods used to choose the best combination of rotor and propeller, this research used Solidworks software computational method. The final result was compared with data-sheets of three commercial rotor specification for quadcopters in order to ascertain its validity. The designed propeller’s size is 16 × 5 inch with two blades, and connected to a rotor having angular velocity between 1000 and 9000 rpm. In order to analyze the air pressure around propeller, Solidworks flow simulation was conducted. Information achieved from analyzed data show that the maximum thrust was 4144 g-force (gf), with propeller’s coefficient thrust of 0.04. These data can be used to analyze the power efficiency in rotor propeller which is then useful in choosing the right size of propeller, according to the desired thrust.

This paper deals with the design of cooperative mobile manipulators, that are not simply considered as the union of an existing mobile platform with an arm, leading to a highly redundant system, but as a system redesigned from scratch with an original minimal kinematics suitable for robot-robot collaboration. In order to design cooperative mobile manipulators adequate with the environment and the considered task, functional specifications are first expressed and partially translated into constraints on the structural parameters, both for single robotic units (m-bots) and the poly-robot resulting of the cooperation (p-bot). This method allows to obtain a set of robotic architectures that also verify other functional specifications.

Building a robot requires knowledge from very different fields. In order to achieve even a very simple task, it requires complicate systems. Robots must, generally, feel to be able to get information about the environment. A robot must “understand” what happens, build plans or assess situations. Domains where robots are being used more and more are: transport and agriculture, various industries, in services, in scientific research, the knowledge of the ocean and outer space. The robots are equipped with various devices: systems for voice recognition, gyroscopes systems, wireless communication systems, global positioning systems (GPS) and various types of sensors (for detecting heat, force, ultrasound, chemicals and radiation etc.). This paper presents the opportunity for using a mobile robot for testing an inaccessible environment for humans and, eventually, the detection of a hostile area.

For handling tasks requiring high accuracy and high dynamics, good stiffness properties of the manipulator are crucial and need to be taken into account in the design phase. Known methods to calculate the stiffness properties of a mechanical structure are the Finite Element Analysis, the Virtual Joint Method and the Matrix Structure Analysis. These methods trade off the complexity and computational costs against the accuracy of the results. This paper presents an extended procedure to model and analyze the stiffness properties of mechanical structures based on the Matrix Structure Analysis. The stiffness matrix of the structure is assembled automatically, following the described algorithm. The deformation of the structure under external load can then be calculated directly. In this procedure, complex links and joints with force dependent (non-linear) stiffness properties can be taken into account. This extended procedure is validated by measurements on a robotic arm.

The kinematic pair Pa2 is composed of two interlinked parallelograms. It has two degrees of freedom that generate a translational plane variable with position. It has a structure different from the PaPa pair, which is composed also by two parallelograms but generates a constant translational plane. Currently, the Pa2 pair is used at conceptual level but it is not used in almost any practical application. There are advantages and drawbacks in using it. The main drawback is the high number of redundant constraints that this pair possesses. However, substituting carefully the revolute joints by spherical joints can eliminate these redundant constraints. Also, this pair constitutes a more rigid structure that replaces adequately the problematic passive prismatic joints. In this paper, will be presented a preliminary study of a translational parallel manipulator (PM) based on the use of the Pa2 pair: the 3-PPa2 that contains redundant constraints in its global structure. To study the potentiality of the PM presented in this paper, the following analyses will be done: position and velocity (direct and inverse kinematics), workspace and singularity analysis. Also the potentiality to be optimised will be studied.

Spatial object manipulation is subject to various parameters, which can be optimized by means of suitable motion strategies. In addition, corresponding strategies can be adapted to specified handling devices enabling efficient motion design with respect to kinematic and dynamic characteristics of particular manipulators. Further optimization is provided by the application of robot redundancy, whose resolution can be adapted to efficient motion planning. In this context, parallel kinematic systems featuring kinematic redundancy or a redundant actuator concept can be operated with an optimal set of actuator parameters allowing a resource-efficient object manipulation. This contribution is devoted to the conception and modeling of redundantly actuated parallel kinematic manipulators (RA-PKM) in order to realize optimal configuration strategies and motion design. Accordingly, the structure selection and the dimensional synthesis of a translational RA-PKM are presented based on parametric kinematic and dynamic modeling. Corresponding models provide an application-oriented transformation from intuitive CAD design software to technical computing and simulation software. The developed manipulator is suitable for the comparison of different redundant and non-redundant actuator configurations as well as optimal trajectories. Concluding analyses exemplarily refer to a non-redundant 3-arm and a redundant n-arm PRPaR system.

The 6-Prismatic-Spherical-Spherical (6-PSS) joint kinematic chain based parallel mechanism is discussed. The stationary active axes in 6-PSS mechanisms in reference to base serve many design concepts and the varied applications of this are detailed. The design concept of 6-axis stiff wrench sensor is presented; the prototype based on 6-PSS chain is demonstrated. The mechanical master-slave manipulator design is shown and a three dimensional model and simulation is presented. The cam and the follower for a joint space prismatic displacement are proposed and the design is presented. Single actuator, tunable, specific spatial path following manipulator design concept is presented. The design and implementation of a single actuator shaker to operate in a six dimensional space based on a PSS joint configuration is demonstrated. The kinematic design analysis for generating an infinite signature set is given. The specific path based single actuator concept is extended to an array of 6-PSS manipulator based on the cam and the leg follower connected to a common drive shaft.

This paper presents a compliant rotary actuator composed of a monolithic plastic structure and a shape-memory-alloy (SMA) wire. The plastic structure features a helical shape. The SMA wire can be permanently deformed at ambient temperature. It is first pre-strained in tension, then wrapped on the helical structure and fixed at its two ends. The SMA wire is finally heated by Joule effect, leading to a continuous rotation between the two ends of the plastic structure. The rotation angle is driven by varying the intensity of the electric current. A preliminary prototype has been built and first results are presented.

A large group of mechatronic systems currently consists of parallel robots, which are largely used in various applications due to their advantages over conventional serial mechanisms: high rigidity, high load capacity, high velocity and high precision. The synthesis of a mechatronic system, hereby represented by the parallel robots, envisages a balance between modelling and simulation and experiment. The structural modelling of the parallel mechanism within these robots is an essential stage of the synthesis and uses the concept of the kinematic connections. The paper outlines how a linear actuator materializes the KB(−1) and KC connections. The modelling, the simulation and the experimental analysis of a linear actuator are developed. The authors explain that using the theory of kinematic connections has the advantage of a fast and simple implementation.

The paper deals with the control problem of a class of hyper-redundant robots constituted by a chain of continuum segments. The main parameter, the system state, is determined by the position and velocity generalised variables. The dynamic model is studied and the constraints of the state variables and nonlinear components are proved. The observability problems are solved by an approach derived from the Luenberger observer type extended for this class of non-linear distributed models. The inequality constraints on the gravitational components allow to introduce a decoupled control system. A PD boundary control algorithm is used in order to achieve a desired shape of the arm. The stability analysis and the resulting controllers are obtained using Liapunov techniques. The exponential stability of the (error-observer) system was proved. The constraints on the observer and controller gains are analysed. Experimental tests verify the effectiveness of the presented techniques.

In this paper we illustrate the feasibility of using control moment gyroscopes (CMGs) for the stabilization of free swinging robots hanging from single tendons. Such systems may provide robotic workspaces of unprecedented size, especially in the vertical. Taking typical base reaction forces of industrial robots we show that control moment gyroscopes may provide means for compensation. From the basic principles of CMGs we derive design criteria for a free swinging robot platform. These criteria are illustrated in the design of a scissored pair CMG for a single DoF demonstrator.

Machining with anthropomorphic robotic manipulators is used to increase the flexibility and reduce the costs of production. The productivity in robotic machining process is limited by low rigidity of robot structure and vibration instability in machining (chatter). Chatter analysis in robotic machining process is a challenging issue due to the variability of the dynamic behavior of the serial robot in its workspace. Hence, a dynamic model which correctly takes into account these variations is important to define adequate cutting parameters and adequate robot configurations to be adapted along the machining path. In this paper, a multi-body dynamic model of a machining robot is elaborated using beam elements which can be easily simulated for machining trajectory planning. The beam elements geometry, elasticity and damping parameters are adjusted by experimental identifications. A stability diagram based on regenerative chatter in milling operations is established. Due to variations in the robot’s dynamic behavior along a machining trajectory each posture of the robot has its own stable cutting conditions. Therefore, this paper proposes a three-dimensional representation of a stability lobes diagram for the prediction of chatter vibrations in robotic machining. Stability prediction established through the proposed numeric model is validated by experimental machining tests with the ABB IRB 6660 industrial robot.

This paper addresses the dynamic control of a 2PRP-2PPR vertical planar parallel manipulator. This proposed manipulator can be used for the purpose of lower limb rehabilitation applications (in specific sitting/lying type of lower limb rehabilitation applications). The kinematic and dynamic model of the proposed manipulator are derived and discussed. An augmented PID control along with an uncertainty estimator is proposed for the motion control of the manipulator. The proposed system performance along with the motion controller is demonstrated numerically for the application of lower limb rehabilitation therapies using a clinically recorded gait data. The robustness of the controller and its parameter sensitivity are analysed through different operating conditions and their results are presented. Note: P—stands for Prismatic/translation joint and R—stands for Rotary/revolute joint.

In this paper the developed wireless IMU (inertial measurement unit) system for human motion characterisation has been described. The experimental layout, test modes and protocols were defined. The experiments for the knee joint characterisation during walking on an inclined treadmill were presented. The human knee joint’s characterisation with the usage of IMU sensors communicating with an Arduino board connected to a computer, was presented by plots and numerical data from experiments.

Starting from a previous research regarding Jansen type leg mechanism that was implemented in the structure of a walking robot, few problems were identified. One of these problems was related to the reduced number of DOFs that it possesses and the step height described by the end point of the leg during walking. After conducting a series of simulations regarding the path curves described by the end point of Jansen’s leg configuration, a limited number of paths are analysed. In spite of the numerous possibilities for varying the link lengths, it has been observed that for a slight variation of the distance between the fixed joints along horizontal axis, the step height can be increased. The shapes of the path curves described by these modified configurations are analysed and compared with the original one based on the length and the height of the step values. Based on the observations made upon the new path curves obtained a practical solution is proposed. This consists in adding a second DOF to the leg mechanism that will allow adjusting the distance between the fixed joints.

To assist standing-up motion from the deep flexion state, an assisting instrument using driving springs on the hip and knee joints has been developed. This instrument consists of an assisting mechanism for the hip joint which has an oscillating follower type cam with a spring drive, and an assisting mechanism for the knee joint which has a non-circular gear, two grooved cams and a loading flat spiral spring. Especially, to apply it to the deep flexion and extension motions of the hip and knee joints, a motion of standing-up from a flat floor is analysed. As a result, it is clear that the assisting force on the hip joint are needed in case of an extension from the deep flexion state, and that force on the knee joint are needed during all extension motion state. Furthermore, the prototype instrument has been tested, and it is confirmed that the instrument is useful for the standing-up motion.

Brachytherapy (BT) is a procedure used to treat cancer by inserting needles directly into the patient’s tumour tissue in order to deliver radioactive seeds. The efficiency of this procedure is obtained by minimizing the number of inserted needles and generating safe trajectories that avoid critical areas. To increase the accuracy of needle insertion, the physician is replaced by a robot. The paper presents an evolutionary algorithm used to generate trajectories for needles inserted by an innovative BT parallel robot. Given the locations of the points representing the seeds and the 3D virtual model of the treatment area, the proposed solver allows the minimization of the number of inserted needles and the planning of needles trajectories that avoid high risk areas. The solver was validated for a complex BT liver treatment scenario.

In this paper, an overconstrained manipulator is selected for the purpose of rehabilitation of the upper extremity. The geometry of the selected manipulator fits the exact motion of the upper extremity and acts as an exoskeleton. Inverse kinematics calculations are shown for describing the motion of actuators for a desired arm motion. Lagrange Formulation is used for the inverse dynamic model of the system. Due to the geometry of the manipulator, kinematic and dynamic calculations are applied to the two spherical subspaces of the manipulator using imaginary joints.

The widely accepted performance criteria of haptic devices, which are transparency and z-width, are affected by the stiffness characteristics of the haptic device’s mechanism. In addition indirect measurement of the handle pose of a haptic device is also affected by the stiffness characteristic. In this study, image processing techniques are used in the experimental setup to develop a stiffness map of a haptic device. The experimentally developed stiffness map is presented and the results are discussed by addressing future works.

In the field of parallel kinematics few designs use highly deformable elements to obtain the end effector movement. Most compliant mechanisms rely on notches or shape changes to simulate a standard kinematic joint. In this work a kinematic model of a simple parallel continuum mechanism that combines a deformable element and cable is presented. The kinematic model is used to study the workspace of the manipulator and is validated by experimental measurements of a prototype.

Developing a gripper that can realize different shapes of its grasping surface and thus grasp different shaped objects, represents a challenging task. Compliant monolithic structures known as compliant mechanisms represent one way to obtain the gripper that can adapt its grasping surface to different shaped objects. This paper introduce a new concept of an adaptive compliant gripper finger with embedded actuators. By using embedded actuators gripper finger can change the shape of its grasping surface and achieve multiple grasping patterns. Synthesis approach for the gripper finger is also presented. It will be shown that gripper finger can realize complex grasping patterns via embedded actuators (in this paper via combination of contracting and extending actuators).

The paper deals with the dynamic behaviour of a 4DOF parallel robot with decoupled motions, three orthogonal translations and one rotation, in a comparative approach of flexible versus rigid links, and also the influence of friction in the four active prismatic joints. The ADAMS software and its AUTOFLEX module were used to model the parallel robot and further to identify the end-effector motion errors on a representative trajectory, due to the natural flexibility of the robot links, and the variation of the actuating forces needed in the input joints with both links flexibility and active joints friction. The obtained numerical results show significant resultant errors of the end-effector from the planned trajectory, generated by link elastic deformations, and important errors of actuating forces (up to 300 %) in the assumption of both link flexibility and active joint friction. The results are useful for robot designers to optimally select the actuators and appropriate design the control system to ensure trajectory high accuracy on the robot workspace.

The handling of dry, pre-impregnated semi-finished textiles in the production of fibre-rein-forced structures with complex geometries is still performed mainly manually resulting in long processing times, low reproducibility and high manufacturing costs. In this context, the scope of the project AutoHD is to fully automate the draping and handling process of complex, three-dimensional fibre composite structures with high degrees of deformation and multiaxial curvature. Based on the involved subsystems, this contribution presents challenges and progresses of ongoing research and future investigations.