Papers by Keyword: Kinematics

Abstract: In this paper an experimental research was performed in case of a human rehabilitation exoskeleton. The research aim was to evaluate the joint trajectories and the influence of the ground-foot contact by using two distinctive shapes of the exoskeleton foot. Thus an experimental motion analysis was used, called CONTEMPLAS and an exoskeleton prototype with 1DOF placed on a treadmill. The experimental activity was developed when the exoskeleton was used on walking activity. There were studied two types of foot shapes and also the generated impact of their form on the hip, knee and ankle joints trajectories during walking. The obtained results will be useful for the improvement of the exoskeleton orientation in space.

Abstract: The counter-rotating wind turbine is a relatively new concept of wind converter that contains two rotors placed on the same side or on both sides of the nacelle with the aim of increasing the wind energy conversion efficiency. As the rotors are rotating at a lower speed than the generator requires, the wind turbine usually contains a speed increaser to harmonize their running regimes. Similar counter-rotating systems are approached for hydro applications but they are still in the research phase.The paper proposes a novel concept of a 2 DOF speed increaser to be used in counter-rotating systems (wind or hydro). The structural and kinematic features of the 1 DOF and 2 DOF transmission running cases are presented in the paper. The differential transmission is further analyzed and the transmission functions and efficiency are established. Finally, conclusions regarding the use of 2 DOF transmissions in the renewable energy systems are formulated.

Abstract: The paper presents the functional analysis of a parallel robotic system used for transperineal prostate biopsy. A simulation system to study the robot functional analysis was developed using the integrated MATLAB software. Given the fact that the robotic system is used in a medical environment, it has to meet certain safety requirements indicated by the medical doctors. In order to fulfill these needs an appeal to complex simulation software has to be made to help choosing the best kinematic solution for the robotic system. The designed simulation software offers a correlation between the structure of the robot and the surrounding medical environment, pointing out its workspace and possible configurations that might harm the human patient during the biopsy.

Abstract: Abstract: The paper presents the possibility of generating a complex kinematic model that can be used to simulate various types of semi-independent rear axle used in the design of new cars. This model allows quick check for such axles of the interference that may occur in their functioning on the car. For application it was used the CATIA V5 software.

Abstract: The paper presents a possible practical application based on two 6R overconstrained mechanism, more precisely 6R Wohlhart overconstrained mechanism. Two of these mechanisms are put in a mirror position, in order to obtain a car jack. The mechanisms are disposed in other position than the original one, three non-adjacent joints being constrained to remain in a fixed plane.

Abstract: This paper presents the mathematical and structural model as well as the verificationof a designed and built underwater crawler robot. The underwater crawler robot is designed to inspect elements of the water supply infrastructure, including pools, reservoirs and pipelines with round or square cross-sections. The virtual prototyping process is described as well as the various possible uses (design adaptability) depending on the optional accessories added to the vehicle. A mathematical model is presented to show the kinematics and dynamics of the underwater crawler robot, essential for the design stage. The mathematical model was used for a number of simulations and subjected to verification on a real object in two test environments.

Abstract: The ankle joint injuries are very common and their recuperation to fully operational capabilities involves rehabilitation. The existent ankle rehabilitation equipment is simple (like elastic bands, foam rollers) and they allow only simple rehabilitation exercises, which cannot be use safe without the aid of a therapist [1]. Actuated devices are advantageous because they allow many types of exercises on same device, and also they accurate measure forces and angular motions. Thus, the field of rehabilitation robotics is constantly evolving, with novel mechanisms that improve the recovery of the ankle joint. The aim of this paper is to propose a new platform, which can realize a large range of ankle related foot movements. This device can perform plantar flexion/dorsiflexion movements as well as the inversion/eversion movements. A 3D design is presented, as well as input angle variation function of output angle.

Abstract: Planetary speed reducers are used as the actuating module of the revolute joints for the industrial robots as a result of their specific advantages given by high transmission ratios, efficiencies and reliability. However, planetary speed reducers are currently used with variable high speed electric motors, which leads to increased peripheral speeds for the gears and planet carrier, leading in turn to increased noise during operation. Therefore it becomes necessary to manufacture the gears and planet carrier in an upper precision class, leading to significantly increased costs for the entire planetary transmission. Throughout this paper, novel solutions for planetary speed reducers are proposed, characterized by reduced peripheral speeds of the moving elements. For all the structural variants proposed, the summation method (Svamp’s rule) was applied in order to establish mathematical expressions for the transmission ratios. Subsequently, expressions for the peripheral speeds, corresponding to each moving element were derived, and expressed as a function of the number of revolutions of the input shaft. The method described in this paper was applied for each structural variant proposed, the results obtained being compared and analysed, leading to the optimal variant, characterized by a reduced level of noise and vibrations. Based on the mathematical expressions previously derived, a series of graphical representations of peripheral speeds as a function of the number of revolutions for the input shafts were elaborated for each structural variant proposed. At the same time, some recommendations useful for both designers and manufacturers of planetary speed reducers were made, based on the obtained results.

Abstract: In this paper, we describe the development and validation of the kinematic analysis of a low low-cost 4-link robot the first of its kind in Nigeria. This study comprises the following key tasks which describe the methodology for the robot development: design and kinematic analysis of the robot mechanism, construction/fabrication and assembly of the robot, system development (computer interface with the robot) and experimental validation of the robot control. The goal of this robot is to pick an object and drop the object in a specified position. The algorithm to control the robot on the computer was coded in Java and simulated in MATLAB/Simulink platform. The robot was experimentally verified and the results are presented in this paper. The experimental results show that robot development is feasible in Nigeria. The contribution of this study will enhance and promote robot control and development in Nigeria and developing third world countries.

Abstract: The article considers kinematic parameters of the 6R Bricard linkage characteristic point obtained analytically. Computer simulation of this mechanism resulted in diagrams of changes in the special orientation of the coordinate system of the characteristic point and a projection of its velocities to the basic coordinates system. In addition, we developed a prototype model for experimental studies. The difference between data obtained using the experimental model and the data obtained by computer analysis is less than 5%. This article describes the components of the experimental model. Using a stepper motor requires solving additional tasks: resonance, peaks at the first and the last steps, step dividing, ensuring the smooth acceleration of the motor shaft, smooth increasing of the shaft load, etc.