Selected aspects of robin heart robot control

The issues of medical robots have been approached for 12 years in the Institute of Machine Tools and Production Engineering of the Technical University of Lodz. In the last two years, the scope of research related to the miniaturization of surgical tools, automated changing of these tools with the use of a tool depot designed for this purpose, equipping the robot in the sense of touch and developing the software which provides ergonomic and intuitive robot control with the use of all its functions. In the telemanipulator control, strong emphasis is placed on the intuitiveness of control, which is hard to be ensured due to the fact that the robot tool is observed by a laparoscopic camera, whose orientation and position may vary. That is the reason for developing a new algorithm. It copies the increments of the position and orientation measured in relation to the monitor coordinate system onto the robot tool movement and orientation, which are measured in relation to the camera coordinates system. In this algorithm it is necessary to solve inverse kinematics, which has a discontinuity. Avoiding the discontinuity is achieved by mapping the solution with the cosine function. It causes smooth pass through the area of discontinuity in this way avoiding the singularity

Experimental verification of numerical simulation of projectile impact on ballistic shields

In this work, the author presents experimental verification of numerical simulation of projectile impact on constructional shields. The experimental tests were performed at a unified test stand to investigate ballistic resistance of materials in field conditions. The stand was developed at the Polish Naval Academy in Gdynia, and then patented. The design of this test stand was based on construction of a ballistic pendulum, fitted to measure: impact force, turn angle of the ballistic pendulum x, impact velocity and residual velocity of the projectile. All the measurement data were transmitted to a digital oscilloscope and a personal computer. The ballistic velocity of the shield of VBL(R) - defined according to Recht’s and Ipson’s method, was compared with V BL(Z) and VBL(Z1) - determined according to the author’s method. Verification of numerically simulated ballistic velocity VRO versus the before-mentioned velocity was carried out at the 10GHMBA-E620T steel shields impacted by 12.7 mm type B- 32 projectiles. The introduced method can be used for determining ballistic thickness hBL and ballistic velocity VBL for both homogeneous plates as well as multi-layered constructional shields

Improvements in the turbo-engine by replacement of conventional combustion chamber by a pulse combustion chamber

This paper comprises description of the turbo engine and evaluation of its analytical model. The analytical model was created to establish a benchmark for further evaluation of a wave rotor combustor (at constant volume). The wave rotor combustor concept was presented and discussed. Advantages of combustion at constant volume were described as well as the basic turbo engine updates required to reflect pulse combustor application. The calculation results for analytical model of a basic engine, and that equipped with pulse combustor are included in this paper. The paper describes the required changes in the engine structure and construction and the estimated thermodynamic improvements. Axial-type pulse multi-chamber combustion unit increasing the pressure and temperature of gases requires a special additional turbine utilizing additional energy and forming the interface between the standard compressor-turbine unit. Performance calculations done for an existing GTD-350 engine showed that constant-volume combustion process is valuable

Simulation of fluid structure interaction in a novel design of high pressure axial piston hydraulic pump

A novel type of an axial, piston-driven high pressure hydraulic pump with variable capacity marks a significant improvement in the area of the hydraulic machinery design. Total discharge from hydrostatic forces eliminates a need for a servomechanism, thus simplifying operation, reducing weight and introducing the possibility of the pump displacement control by computer. PWK-type pumps, invented in the Gdansk University of Technology, offer high efficiency for pressure levels up to 55 MPa, ability to work self sucking even at high speed. However, the heart of the new invention, the commutation unit, creates harmful pressure peaks. Those peaks can be mitigated by the introduction of a compensation chamber with elastic walls. Owing to the dynamic character of events taking place in the pump, a need for computer simulation arouse in order to understand phenomena leading to the occurrence of pressure peaks and choose compensation chamber parameters accordingly. A CFD package alone would not be sufficient to reliably represent the interaction between the compensation chamber wall and the working fluid. This paper presents Fluid Structure Interaction approach comparing 3 different models: 2 simplified models of the pump and a full pump model.

Mechanical and hardware architecture of the semi-exoskeleton arm rehabilitation robot

This paper deals with mechanical and hardware design of a robot, used for the rehabilitation of upper extremities. It has been called ARR-1 (Arm Rehabilitation Robot). The robot has a semi-exoskeleton structure. This means that some parts of the robot fit closely to the human arm (an orthosis), but the weight of the construction does not load patient’s body. The device is used for the whole arm rehabilitation, but active joints are only situated in glenohumeral and elbow joints. The robot is electrically actuated

A one-dimensional model for the heat conduction in ring-like body

A one-dimensional model based on the Fourier’s theory of heat conduction is developed for ring-like bodies. The ring-like body is an incomplete or complete torus with arbitrary cross section. The thermal properties of considered rings are independent of the polar angle. Examples illustrate the application of model presented

Modelling of vertical shaft of mixed-flow pump

The aim of the work was modelling of shaft and calculation of natural vibration frequencies and critical rotations of a large-size, vertical mixed flow pump of total length l=4866 mm. Equations of motion were determined analytically, and then calculation results were verified by numerical modelling. The difficulty of the problem consisted in the shaft bearing, in which four hydrodynamic bearings of unknown parameters were applied. A four-mass beam supported on flexible supports of rigidity k and damping c was assumed as the discrete model of the shaft. Equations of motion for the system were derived with the method of forces. In order to verify correctness of the derived equations, one considered three models of the beam with different support configuration: the beam supported on rigid supports, the beam supported on elastic supports, and the beam supported on flexible supports of rigidity k and damping c. Calculation results are presented in tables and graphs

Hybrid Reduced Model of Rotor

In the paper, the authors describe the method of reduction of a model of rotor system. The proposed approach makes it possible to obtain a low order model including e.g. non-proportional damping or the gyroscopic effect. This method is illustrated using an example of a rotor system. First, a model of the system is built without gyroscopic and damping effects by using the rigid finite element method. Next, this model is reduced. Finally, two identical, low order, reduced models in two perpendicular planes are coupled together by means of gyroscopic and damping interaction to form one model of the system. Thus a hybrid model is obtained. The advantage of the presented method is that the number of gyroscopic and damping interactions does not affect the model range

A Surveillance Of Dynamic Processes on Selected Mechatronic Systems

The paper concerns development of original method of optimal control at energy performance index and its application to dynamic processes surveillance of some mechatronic systems. The latter concerns chatter vibration surveillance during highspeed slender milling of rigid details, as well as motion control of two-wheeled mobile platform. Results of on-line computer simulations and real performance on the target objects reflect a great efficiency of the processes surveillance