In this paper a new method for achieving isotropic compliance at the contact point is applied to a manipulator for packaging operation. Two different manipulators are considered, namely, PR and PPR. The paper discloses some different strategies for stiffness control, with the purpose of contact force optimization. The control system acts on the controlled joint stiffness in such a way that the contact force, in the Cartesian Space, will be parallel to the displacement of the contact point. Such feature minimizes friction and wear during packaging operations and minimize tangential reactions.

In this paper, a new methodology for the development of the dynamic formulation for a hybrid parallel robot is introduced. The robot includes a tripod that is serially connected on top of a hexapod in order to increase its overall workspace, while maintaining sufficient accuracy and stiffness in motion. The robot will have applications involving gripping and manipulation of large aerospace components such as a wingbox structures and panels. The dynamic formulation of the system, based on Newton-Euler and inverse kinematic equations, is presented by identifying the position vector of the actuators during motion when the system follows certain point and orientation in space. Based on the velocity and acceleration, calculated by taking derivative of the motion equation, the force on the actuator is identified. Since the position vectors of all tripod joints can change through motion, the above methodology offers less complex calculations compared with the existing methods such as using forward dynamics. A MATLAB software was developed to create a set of comprehensive dynamic equations for the overall control system design. An experimental physical hybrid robot was built in order to verify the theoretical formulations. Force sensors, connected at each actuator joint, were used to obtain the applied force on each actuator through a number of given motions. The applied forces subsequently assist to calculate the acceleration of the moving platform. The experimental actuators’ force results compare well with the proposed theoretical formulation.

A new personal device to assist the upper limb capable to be mounted on a wheelchair is being tested. The robot is equipped with three brushless motors powered by four electronic boards appositely designed and communicating via I 2 C protocol; one board works as master for the other three, which have simpler tasks. Most of the driving software has been developed with Matlab and mainly translated into C++ for memory space and boards’ efficiency matters. The system’s end-effector is connected to the subject’s forearm and can cooperate to the arm motion in several different ways. In order to avoid the overstress of the natural joints no further connections are made to the upper limb. The working volume of the limb connected to the device allows the execution of the trajectories required for most of daily living activities. It is addressed to post stroke rehabilitation and to the self-treatment of other patients with serious deficiency of arm forces, like individuals affected by muscular dystrophy. Some working modes exploit the mechanical impedance control to gently interfere with the residual natural motion capability of the subjects. The very preliminary tests of the prototype fitted on a power wheelchair are encouraging: it is light, not too noisy and easy to move for the subject. The first working mode, with full arm gravity compensation, and the second working mode, with partial compensation, have been implemented and are currently being tested with patients, as well as the mode in which the subject is helped to repeat a stereotyped exercise for self-physiotherapy. Beside the fact the control system must be calibrated on patient characteristics, for these initial tasks the system reveals to be user-friendly. Other working modes require to interpret the patient intention to move the upper limb. For a natural approach it is sufficient to decode the movement intention of the patient and the final position he wants the hand to reach, whilst the rest of the limb can be automatically positioned by the system. Different approaches to solve the problem have been experimentally tested, including the use of a headgear with a brain interface. To present knowledge the best results have been obtained by monitoring the movement of another body segment such as the head. The device designed for the functional recovery of upper limb can furthermore be used to monitor and easily certify the evolution of the patient conditions.

The present paper deals with the development of a bench for testing different types of lower limb prostheses. Aim of the bench is to test the prosthetic devices considering working conditions as much as possible similar to the real ones with respect to methodologies provided by International Standards. These standards merely identify structural tests whose purpose is just to verify that the prosthesis, or their individual components, are able to ensure adequate strength properties during their use. The only functional test concern just the ankle-foot units. Test methods for the assessment of the functional performances of the whole prostheses are missing. There are no criterions for such tests and no benches. From this the need to build new test machines that, simulating both the stance and the swing phase according to sought gait standards, allow to assess the functional properties of different lower limb prostheses and to make comparison between them. According to this, the purpose of the present work is to assess the feasibility of such a bench, evaluating, by mean of a co-simulation executed considering a Multi-Body model of the bench developed using MSC ADAMS and a model of the control system developed using MATLAB/Simulink, its capability in guaranteeing the sequential replication of movements and loads that distinguish a leg during the execution of the stride. The obtained results demonstrate the feasibility of the machine, encouraging therefore the development of more refined models, considering technological solutions closer to reality.

The paper presents the motion simulation of a Wing in Ground craft with a Lippisch configuration which is stable in terms of static stability. The influence of wind and wave perturbations on the dynamic stability of the flight are investigated. The analysis of safety and stability used two different approaches. Based on frequency domain simulation, the first approach derived from the classical stability theory utilizes the aerodynamic coefficients and their linearized derivatives. The second approach based on time domain simulation uses the coefficients with full respect to the nonlinear character of aerodynamics in ground effect. The trajectory is used to evaluate the dynamic stability and flight safety of the craft. From the results for typical perturbations, the limitations of the classical stability theory for the flight safety of Wing in Ground craft are shown. The results show the necessity of the automatic control system even for a satisfying stable craft predicted by the linear theory. The demand of high performance together with the hard constraints for states and control inputs are challenging for the controller design. A proportional-integral-derivative controller is studied to secure the flight safety of small craft under different perturbation and a methodology for designing a control system for operation under various weather conditions is illustrated.

In the design of linear control systems, it is desired to assign the closed loop spectrum in sub-regions (as opposed to locations) of the complex plane. The present paper establishes a matrix root-clustering criterion for an important class of regions, and develops a linear feedback control that assigns the closed loop spectrum in the desired region. This is done for both nominal and uncertain systems.

Bearing faults detection at the earliest stages is vital in avoiding future catastrophic failures. Many traditional techniques have been established and utilized in detecting bearing faults, though, these diagnostic techniques are not always successful when the bearing faults take place in gearboxes where the vibration signal is complex; under such circumstances it may be necessary to separate the bearing signal from the complex signal. The objective of this paper is to assess the effectiveness of an adaptive filter algorithms compared to a Spectral Kurtosis (SK) algorithm in diagnosing a bearing defects in a gearbox. Two adaptive filters have been used for the purpose of bearing signal separation, these algorithms were Least Mean Square (LMS) and Fast Block LMS (FBLMS) algorithms. These algorithms were applied to identify a bearing defects in a gearbox employed for an aircraft control system for which endurance tests were performed. The results show that the LMS algorithm is capable of detecting the bearing fault earlier in comparison to the other algorithms.

Micromachining processes deal with the production of parts characterized by features in the micro range (i.e., with dimension lower than 1 mm). Several works are present in literature analyzing the tool behaviors, the material influence on the process, and the machine design. In fact, the downsize of the process up to the microscale needs a full review of all the knowledge coming from the meso and macro scale. As a consequence, machines suitable for micromachining processes were recently introduced in the market. Usually, these machines are classified by the classical gantry layout structure supported by a granite frame and, in order to guarantee the needed requirements of precision and accuracy in the micro scale, they are based on fluid-supported axes and active and/or passive vibration control systems. This paper proposes a new concept design: a high precision machine (HPM) based on an innovative layout exploiting a differential mechanism with three motors for two degrees of freedom using pulleys and metal belts. This new layout exhibits relevant advantages. The most significant is that all the worktable servo drives, that moves along x and y axes, are ground-fixed. This allows to isolate the working area of the machine from the servo drives. The system of pulleys and belts holding the working table slides on air bearings in order to minimize the micro vibrations induced by all the drives. A further peculiarity of the machine consists of the double z-axis each of them is motorized by a micrometer slide with linear absolute encoder. The first z-axis is equipped with a spindle for performing micro machining processes (drilling and milling). The second z-axis is equipped with a laser head for micro ablation. The servo drives of the two z-axes are controlled by the same control system of the worktable. Another important feature of the proposed layout is that the differential configuration of the xy mechanism admits the use of a constant speed signal to each control reference with no output displacements. This allows to guarantee non-inversion of motion of the servo-drives and so the avoidance of problems due to backlash and/or static friction. Drives are controlled by position and speed control loops with PID architecture, anti-windup and feed forward strategies. Controllers have been tuned by the use of a genetic algorithm applied to a dynamic model of the system. As a general consideration, the quality of the investigated micro machining processes can be improved with the designed machine structure.

All over the world, several dozen million people suffer from the effects of post-polio, multiple sclerosis, spinal cord injury, cerebral palsy, etc. and could benefit from the advances in robotic devices for rehabilitation. Thus, for modern society, an important and vital problem of designing systems for rehabilitation of human physical working ability appears. The temporary or permanent loss of human motor functions can be compensated by means of various rehabilitation devices. They can be simple mechanical systems for orthoses, which duplicate the functions of human extremities supplying with rigidity and bearing capacity or more complex mechatronic rehabilitation devices with higher level of control. We attempt to cover all of the major developments in these areas, focusing particularly on the development of the different concepts and their functional characteristics. The robotic devices with several structures are classified, taking into account the actuation systems, the neuromuscular stimulations, and the structural schemes. It is showed that the problems concerning the design of rehabilitation devices are complex and involve many questions in the sphere of biomedicine, mechanics, robot technology, electromechanics and optimal control. This paper provides a design overview of hardware, actuation, sensory, and control systems for most of the devices that have been described in the literature, and it ends with a discussion of the major advances that have been made and should be yet overcome.

An original method for the real-time estimation of the roll angle using low-cost sensors in two-wheeled vehicles is proposed. The roll angle greatly affects the dynamics of single-track vehicles and its estimation is essential in control systems such as ABS, Traction Control, as well as Curve and Collision Warning, or even active suspensions. The proposed method uses a non-linear Kalman filter, its performances are assessed by using both a set of simulated data from a multibody model and a set of real data collected on an instrumented test vehicle.

The paper deals with exact null-controllability problem for a linear control system governed by smooth controls. Applications to the exact null-controllability for partial parabolic equations are considered.

In haptics applications actuators with compact volume and high force output are desired for stable and stiff interfaces. Magnetorheological (MR) brakes are viable options since they have large force-to-volume ratios. However, linear MR-brakes available on the market have limited stroke due to the piston-cylinder design and show viscous damping behavior where the force output highly depends on the velocity of the actuator resulting in a high off-state friction force. Another problem is the inherent magnetic hysteresis, which requires complex control systems. In this research, we focused on the development and control of a linear MR-brake with infinite stroke and minimal off-state friction. The common piston-cylinder arrangement was removed from the design to address the limited stroke and high off-state-friction issues. The serpentine flux path methodology was followed to achieve compact geometry. Three control strategies namely, open-loop control, force feedback control, and current feedback with Preisach model, were implemented on the developed prototype. The results using Preisach model showed that the hysteresis could be reduced significantly without the need for an expensive force sensor in the control loop. Our new device has a 3% ratio of the off-state friction force to the maximum force output in comparison to more than 10% for most MR-damper devices in the literature. At the same time, our prototype is about half the size of a commercially available product.

This paper presents a fluid-dynamic analysis of the hydraulic circuit of a shaking table for seismic tests; the model was developed adopting a commercial code. The aim of the study is to provide useful indications for the design of a new optimized control system. The model was developed taking into account all the components of the hydraulic circuit that is made of by the following main items: the axial piston pump, the pressure relief valve, the main control valve, the accumulators, the hydraulic cylinder with variable displacement and all the connecting pipes. Particular attention was given to the modelling of internal resistance of the hydraulic system, that can greatly affect the performance of the shaking table. It has also been accurately modelled the main valve dead zone to highlight its influence on the system dynamics. The results of numerical simulations obtained for different operational conditions are reported and compared with experimental data to show the validation and the performances of the developed model.

In this paper is described the main ideas of national project “KEGA 3/7131/09 – Laboratory of production system program control”. This project is focused to build of virtual laboratory and supplemental e-learning documents for several studying subject at our institute. This project being solved in the Institute of Production Systems and Applied Mechanics, Faculty of Materials Science and Technology – STU in years 2009–2011 includes an opportunity to acquire and improve abilities and skills the employers expect technical university graduates to have. The project target is to create a virtual laboratory of programmable control systems and a suitable teaching system supporting creation and improvement of key and occupational competences, abilities and skills of students in technical fields of study promoting at the same time their preparation for practice and lifelong education.

Optimal revenue of oil and gas fields is of interest due to high price and limited amount of these sources of energy. In this way, smart well technology provides a numerous range of benefits and for these great advantageous is widely used in oil/gas industry. This technology involves down-hole measurement and control of well bore and reservoir flow. One of the most important down-hole control subsystems in a smart well is pressure and temperature sensing system which can help the reservoir being modeled accurately. The purpose of this paper is to design and analysis a new sensory package for a desired oil well. A brief review of the advantages of fiber optic sensing technology in smart well control system is performed. Having studied several possibilities of installation systems for sensors, a new arrangement and casing for temperature/pressure sensor is developed here. Effect of pressure and temperature on stress distribution in the casing has been investigated and a suitable casing is obtained.

A novel semi-active control system for suspension systems of passenger car using Magnetorheological (MR) damper is introduced. The suspension system is considered as a massspring model with an eight-degrees-of-freedom, a passive damper and an active damper. The semi-active vibration control is designed to reduce the amplitude of automotive vibration caused by the alteration of road profile. The control mechanism is designed based on the optimal control algorithm, Linear Quadratic Regulator (LQR). In this system, the damping coefficient of the shock absorber changes actively trough inducing magnetic field. It is observed that utilizing the present control algorithm may significantly reduce the vibration response of the passenger car, thus, providing comfortable drive. The new developed suspension system may lead to design and manufacturing of passenger car in which the passenger may not feel the changes in road profile from highly bumpy to smooth profile.

Active and semi-active suspension systems are widely diffused into the automotive industry and several control strategies have been proposed in the literature both concerning ride comfort and handling. The capability of several suspension active control systems in enhancing the vehicle handling performances are compared in this paper. In particular, a low-bandwidth active suspension (actuator in series with the suspension spring), an active antiroll bar, an active camber suspension and a semi-active high-bandwidth suspension (closed loop damper control) are considered. The benchmark is represented by an ideal vehicle which does not present any load transfer and has no yaw moment of inertia. The possibility of combining more than one active/semi-active suspension system is also discussed.

A turbo generator unit at Al-Khobar power and desalination plant (7 years old) was unable to start due to high vibration. Vibration trend increasing was noticed in the beginning of 2006 and inflated in 2007 due to unbalance which came to acceptable limits after rotor low speed balancing. Fortunately, this inspection prevented a complete damage of turbine due to detached of casing’s top pressure sensor’s sleeve which was digging into nozzle box body and created a big hole and was few millimeters from the rotor. Site repair was done for the nozzle box as per OEM procedure and sensor was omitted since it is not related to control system. In addition, both journal bearings were getting discoloration and pitting in left side due to selected operation mode of steam admission (partial arc mode) which shifting axis of rotation to left side by 30 μm and increases vibration reading compare to full arc mode. Also, another unit found with similar problems which seems to be a design issue. So an assessment study was done to evaluate the design.

The piezoelectric smart structure is a force-electric coupling structure, and piezoelectric patches can not be patched ideally, so it is difficult to build the accurate mathematical model of piezoelectric smart structure. The traditional vibration control methods depend on the structural mathematical model, and the control result is unsatisfactory. Considering this problem, this paper introduces the nonlinear generalized predictive control algorithm based on neural network predictive model into piezoelectric smart structure. Because of the difficulties of building the mathematical model and extracting dynamic data from experiment, the finite element software (ANSYS) is employed to analyze and obtain the dynamic response data of piezoelectric smart structure through modal analysis and transient analysis. Neural network predictive model of structure is built through off-line training on the basis of the data. The nonlinear generalized predictive control based on neural network has a better ability to solve complex nonlinear problem. Then the author introduces the Neural Network Based System Identification Toolbox (NNSYSID) and Neural Network Based Control System Design Toolkit (NNCTRL), which are two special toolboxes for designing neural network control system and can save lots of time for designers who can commit themselves to sixty-four-dollar question. At last, the author shows the method through a case. A cantilever beam which surface is boned piezoelectric patches used for sensor and actuator respectively is analyzed by ANSYS and controled by the neural network predictive control algorithm on the platform of NNSYSID and NNCTRL. This is a simple and effective method for designers to solve the vibration control problem of piezoelectric smart structure.

Vehicle Stability Control systems (VSC) for four-wheeled vehicles like the electronic stability program (ESP) helped to decrease the number of traffic deaths in Germany to an all-time low over the last ten years. However, the number of people killed in powered two-wheeler accidents has been almost constant over the same period of time. Vehicle Stability Control systems for powered two-wheelers (especially motorcycles) so far include only anti-lock brakes and traction control systems, both systems are not designed to work in cornering. Further stability control systems are not known up to now. The objective of this paper is to assess the technical possibilities for future Vehicle Stability Control systems and the amount of accidents that could be prevented by those systems. From an accident analysis, all accidents not avoidable by today’s VSC Systems have been analyzed. Only accidents while cornering without braking have been determined as potentially avoidable by future technical systems (braked accidents have been counted as preventable by improved today’s systems). The accidents can be caused by insufficient friction (e.g. slippery road surface, sand, oil or to high curve speed). About 4 to 8 percent of all motorcycle accidents are of this type. The data source for accident descriptions were interviews of motorcycle experts who were able to describe their own accidents and detailed accident descriptions from an accident database. The accident types have been investigated with driving experiments and computer simulation. With a vehicle model different ways to influence the critical driving situations could be analyzed and evaluated. Experiments and simulations showed an instable roll and side-slip angular acceleration of the motorcycle during critical driving situations. The sideslip rate proved to be a robust criterion for recognizing whether a driving situation is critical. The roll movement of the vehicle cannot be influenced with reasonable means, because neither the lateral tire forces can be increased nor stabilizing gyros can be used since the necessary angular momentum is to large for a feasible package. The vehicle sideslip rate can be influenced by braking the front or the rear wheel, thus generating a yaw moment to avoid the dangerous high-side type accidents when friction changes back from low to high. The motorcycle accidents influenced by this system are only a small portion of the mentioned accidents, so as a result of this study, the potential for future vehicle dynamic control systems that help prevent non-braking cornering accidents is estimated quite low.