In this thesis, the dynamic responses of harmonic drive (H.D.) systems under different operating conditions are investigated. The numerical simulation and the experimental measurements of harmonic drive systems are included in this thesis. The effects of flexspline of harmonic drive, i.e., the torsional stiffness and the damping ratio on the response of corresponding system are studied .Lagrange¡¦s equation is employed to derive the equation of motion of the system. The system equation with a nonlinear torsional stiffness is solved by using the 6th order Runge-Kutta method. Comparison between numerical simulation results and experimental measured data indicate that the proposed harmonic drive model is accurate and feasible for simulating the dynamic response of a harmonic drive system.

The task of constructing a transmission has been provided to us by Digital Engineering, which is a company located in Hovmantorp. After meeting with Digital Engineering we started immediately with the brainstorming to find different ideas with pen and paper. After having presented a number of concepts for the company, we had finally chosen a winner. For the gearbox to be able to work in a good way the tension must never exceed the strain limit of the material. A prototype of the gearbox was produced by TKB Modell. Standard components that are available have been purchased from Sverull AB in Växjö.

In my research, I have performed an extensive experimental investigation of harmonic-drive properties such as stiffness, friction, and kinematic error. From my experimental results, I have found that these properties can be sharply non-linear and highly dependent on operating conditions. Due to the complex interaction of these poorly behaved transmission properties, dynamic response measurements showed surprisingly agitated behavior, especially around system resonance. Theoretical models developed to mimic the observed response illustrated that non-linear frictional effects cannot be ignored in any accurate harmonic-drive representation. Additionally, if behavior around system resonance must be replicated, kinematic error and transmission compliance as well as frictional dissipation from gear-tooth rubbing must all be incorporated into the model.

Wheelchair-bound individuals who have limited or no upper-limb usage have difficulty with picking and placing of objects, opening doors, and other activities of daily living (ADLs), such as turning on a light switch or drinking from a cup. A wheelchair-mounted robot arm (WMRA) would aid individuals with completing ADLs and increase their independence, therefore an improved WMRA has been designed. Building upon previous WMRA research and incorporating research from industrial robot arms, carbon fiber tubing is the main component for the structure of the arm, a novel development for WMRAs. Factors that go into WMRA design include weight, speed, safety, robustness, cost, and the anticipated tasks. Many of these factors, such as weight, speed, and cost, can be improved upon compared to previous WMRAs by using carbon fiber materials. The use of carbon fiber enables the arm to be strong, but also lighter weight than other WMRAs. Testing was conducted on the pultruded carbon fiber tubing to ensure that the structure of the arm could withstand the necessary bending and tensile forces for the arm to hold up to 3.85kg, the standard weight of a gallon of milk, at the end effector. The arm's carbon fiber frame also allows the motor and sensor wiring to run internally, which improves the arm's safety and aesthetics, while protecting it from the arm's external environment. Lightweight high-torque motors, harmonic drives, newly designed carbon fiber frame, and a stand-alone 8-axis motion-control board, allow the arm to weigh less, have a longer overall length, be more robust, and be safer electronically than the previous University of South Florida WMRA, which was shown through prototype testing.

In this study, the use of modified genetic algorithms (MGA) in the parameterization of the Transmission Mechanisms is facilitated. The new algorithm is proposed from the genetic algorithm with some additional strategies, and yields a faster convergence and a more accurate search. Firstly, this near-optimum search technique, MGA-based ID method, is used to identify the parameters of a system described by an ARMAX model in the presence of white noise and to compare with the LMS (Least mean-squares) method and GA method. Then, this proposed algorithm is applied to the identification of the Transmission Mechanisms of DC motor. The parameters of the friction force and DC motor are estimated in a single identification experiment. It is also shown that this technique is capable of identifying the whole transmission system. Finally, the Minimum Variance Controller (MVC) is taken to track the desired speed trajectory and then a comparison to the conventional digital PID controller is shown. Experiment results are included to demonstrate the excellent performance of the MVC.

This diploma thesis deals with design of positioning unit for laser spectroscopy and its realization to shape of prototype. The design of positioning unit is based on the analysis of the current state of knowledge in the field of remote laser spectroscopy systems. Precise harmonic drive and worm drive with stepper motors are used to drive. The main parts of positioning unit are designed primarily from duraluminium. The positioning unit will be used for experimental measurements at the Institute of Physical Engineering Faculty of Mechanical Engineering Brno University of Technology. 3D digital prototype and technical drawings were created in Autodesk Inventor 2010.

No description available.

Dans la continuité des travaux de recherches sur les systèmes de transmission mécanique embarqués, l’objectif de cette thèse est double : approfondir les modèles d’estimations des pièces d’un Actionneur Electromécanique (EMA) et étendre la vision transversale de la conception préliminaire aux aspects dynamiques. En effet, cette recherche permet, lors de la conception préliminaire basée sur les modèles, d’adapter les choix d’architectures et de technologies vis-à-vis des performances statiques et dynamiques à atteindre. Les modèles développés à partir des lois d’échelles sont étendus et exploités afin de modéliser les pièces élémentaires de l’EMA et de faire ressortir les règles de « bonnes pratiques » en conception préliminaire. On s’intéresse en particulier au dimensionnement des EMAs dans le domaine aéronautique. Dans un premier temps, nous avons donc créé des modèles d’estimation et des métamodèles des pièces de l’EMA. A cet effet, il est décomposé en carter et pièces élémentaires qu’il intègre.Dans un second temps, nous avons établis des règles de bonne conception et des pistes de dimensionnement de l’actionneur asservi en position. Contrairement aux recherches antérieures, qui se centraient sur le dimensionnement en puissance, nous avons pris en compte la synthèse de la commande pour établir ces règles. A partir de modèles de simulations, nous qualifions et quantifions l’influence des défauts (inertie et saturations, élasticité/jeu, frottement) sur les performances limites de l’EMA. En effet, les structures de commande usuelles et le choix des éléments de contrôle-commande sont intimement liés aux performances dynamiques et à ces défauts. Enfin, afin de se doter de moyens d’essais pour identifier finement un modèle de frottement dans des conditions aéronautiques de température, un banc d'essai sur le réducteur Harmonic Drive a été conçu et mis en œuvre. Il permet également d’amorcer la validation des règles de bonne conception / In the continuity of work of research on embedded systems of mechanical transmission, this these has two objectives: to improve estimation models of Electromechanical Actuator (EMA) pieces and to extend the cross-cutting vision of preliminary design to the dynamic aspects. Indeed, in the preliminary design based on models, this research should allow to adapt the choice of architectures and technologies to static and dynamic performance to achieve. The models developed from the scaling laws will be extended and exploited to modelize elementary pieces of the EMA and to highlight rules of "good practices" in preliminary design. We focus in particular on the design of EMA in aeronautic field. In the first time, we developed estimations models and métamodèles of elementary components of EMA which was decomposed in housing and elementary pieces.In a second time, we established rules of good practices for actuator sizing in control position loop. Contrary to older researches, we take into account control synthesis to create these rules. From simulations models, we quantified the influence of technological defects of components (inertia and saturations, elasticity (backlash), friction) on EMA performances. Indeed, the usual command structures and the choice of the elements of control are intimately linked to the dynamic performance and these defects.Finally, to give test way to identify with accuracy a friction model in aeronautical conditions of temperature, a test bench of Harmonic Drive was create, integrated and implemented. It allows booting the validation of rules of good practices in preliminary design.

Els robots caminadors presenten alguns avantatges respecte als tradicionals robots mòbils amb rodes, que es resumeixen en major mobilitat i capacitat de superació d'obstacles. Un dels principals problemes actuals en el desenvolupament de robots caminadors és l'elevat consum energètic i la poca autonomia, com a conseqüència de l'elevada massa dels accionaments i del seu rendiment limitat.Un primer objectiu d'aquesta tesi és desenvolupar i caracteritzar energèticament un accionament rotatiu per a les articulacions de la pota d'un robot caminador. Un cop desenvolupat aquest accionament s'analitza el comportament energètic global de la pota.La pota dissenyada és de tipus insecte i l'aplicació considerada és un robot hexàpode. L'accionament rotatiu consta de tres elements: un motor de corrent continu, una transmissió per corretja dentada i un reductor Harmonic Drive. El conjunt d'aquest reductor s'ha dissenyat específicament per a aquesta aplicació, i materialitza també l'enllaç de cada articulació de la pota.Per tal de determinar els requeriments mecànics a les articulacions, s'ha portat a terme una simulació dinàmica del moviment de la pota. Aquesta simulació s'ha realitzat considerant que les articulacions del mecanisme són ideals. Les resistències passives d'aquestes es tracten posteriorment al analitzar el comportament del reductor. Els resultats obtinguts són els parells requerits a les diferents articulacions al llarg d'un cicle.Amb l'objectiu de determinar el comportament real dels components de l'accionament, per a diferents condicions de funcionament, s'han plantejat i realitzat diverses sèries d'experiments. Per portar a terme els experiments ha estat necessària la construcció d'un prototipus de l'accionament. A partir de les dades experimentals s'han definit uns models matemàtics que representen les resistències passives a cada component de l'accionament per a diferents condicions de funcionament. S'ha realitzat un ajust per mínims quadràtics per tal determinar els paràmetres dels models que millor ajusten els resultats a les dades experimentals.Com que cada motor treballa com tal o com fre, segons la fase del moviment, s'ha analitzat en detall el funcionament d'una màquina elèctrica de corrent continu d'imants permanents, des del punt de vista de la conversió de potència elèctrica en mecànica i viceversa, en els 4 quadrants i tenint en compte els diferents modes de funcionament: com a motor, com a fre-generador i com a fre.Posteriorment s'han definit uns models globals del comportament mecànic dels elements de transmissió de l'accionament: la corretja dentada i el reductor HD, que integren la modelització de les resistències passives i també inclouen la inèrcia de les parts mòbils de cada element.Finalment s'ha realitzat la simulació dels tres accionaments d'una pota al llarg d'un cicle de l'anadura del robot, a partir dels requeriments de parell i velocitat angular a cada articulació i utilitzant els models dels elements definits anteriorment. L'objectiu és estimar l'energia intercanviada a cada element de l'accionament, avaluant per separat l'energia transmesa en sentit directe, des de l'alimentació del motor a la sortida del reductor, i en sentit invers. El resultat més important és l'estimació de l'energia elèctrica que cal subministrar a cada motor per cada cicle de moviment de la pota.Dels diversos casos analitzats se'n treu la conclusió que l'energia elèctrica que cal subministrar als motors és sempre molt superior, de l'ordre de 30 vegades, a l'energia mecànica que l'accionament transmet a l'articulació. La despesa energètica dels motors depèn poc de les condicions de càrrega a les que està sotmesa la pota, en canvi el moviment que descriuen les articulacions al llarg del cicle hi té una influència important. Reduint el recorregut angular del moviment de les articulacions s'aconsegueix un considerable estalvi energètic, doncs disminueix l'energia dissipada per les resistències passives. / Walking robots have some advantages respect to the traditional mobile wheeled robots. These can be summarised in superior mobility and the capacity to overcome obstacles. One of the main problems in the development of walking robots is the high energy consumption and the low autonomy of operation, due to the high mass of the actuators and their limited efficiency.A first objective of this thesis is to develop a rotary actuator, for the leg pin joints of a walking robot, and to characterize it energetically. Once the actuator is developed, leg global energetic performance is analysed.The leg design is according to an insect type leg and the considered application is a hexapod robot. The rotary actuator consists of three elements: a DC electric motor, a synchronous belt transmission and a Harmonic Drive gear reducer. Gear assembly has been particularly designed for this application, and integrates pin joint implementation.In order to determine the mechanical specifications at the joints, a dynamic simulation of the leg movement has been carried out. For this simulation pin joints in the mechanism have been considered as ideal joints. Resistance to motion at the joints are taken into account later, when gear operation is analysed. Results from the simulation are the required torques at the different joints along a walking cycle.Several series of experiments have been planned and carried out in order to work out the real behaviour of the actuator components under different working conditions. The construction of an actuator prototype has been necessary for the experimentation.Then derived from the experimental data, mathematical models that estimate resistance to motion at every actuator component as a function of the working conditions, have been defined. Parameters in the models to best fit the experimental data have been identified by least square approximations.Every DC motor works as a motor or as a brake depending on the movement stage. Therefore the operation of a permanent magnet DC electric machine has been analysed, from the point of view of the conversion of electrical power into mechanical and vice versa. This was performed taking into account the different operation modes: as a motor, as a brake-generator and as a brake.Global models that represent the mechanical behaviour of the transmission components in the actuator have been defined: the synchronous belt and the HD gear. These models integrate resistance to motion estimation and also the inertia of the mobile parts of every element. Finally, starting from the torque and angular velocity requirements at every joint and using the models of the elements described above, the simulation of the three actuators of a leg along a gait cycle of the robot has been carried out. The objective was to estimate the exchanged energy at every element of the actuator, separately calculating the transmitted energy in both directions: from the motor power supply to the output of the gear reducer and in reverse. The main result was the estimation of the electrical energy that must be supplied to every motor per leg movement cycle. From the several cases that have been analysed, it can be concluded that the electrical energy that has to be supplied to the motors is always much higher, around 30 times higher, than the mechanical energy that the actuator transmits to the joint. Motor energetic consumption has low dependence on leg load condition, but pin joint movement along a cycle has a great influence on it. Reducing the angular run of pin joint movements is a way to obtain substantial energy savings, since it decreases the resistance to motion energy dissipation.

This thesis deals with the design of a dynamic model of a harmonic drive. It includes a theoretical study aimed at the analysis of the harmonic drive gearing principle and its nonlinear properties. The first part of the practical section deals with the analytical calculation of the nondeformed geometry of the Flexspline. Based on these results, several simulations in ANSYS are created to identify torsional characteristics of a harmonic drive. These simulation models are further enhanced by the analysis of clearance, backlash and inaccuracies and their impact on torsional properties. By using MATLAB /Simulink, several dynamic submodels are created representing the individual characteristics of nonlinearities in harmonic drives. Furthermore, a comprehensive dynamic model is created of the mechatronic system which is describing all nonlinearities and kinematic error of the transmission. The dynamic model is also experimentally verified based on its damping properties.