Sorin Dumitru

Dynamic Analysis of a Mobile Mechanical System with Deformable Elements

The paper presents a method for studying mechanisms with deformable elements, based on overlapping the solid rigid motion over the elastic solid one, in order to identify the dynamic response of the system. Modeling was based on finite element method, so the cinematic elements were meshed in bar type finite elements and the degrees of freedom per node were settled according to the motion character (planar or spatial). A Lagrange formulation of the finite element was adopted for the deformable elements connected in multibody systems. In order to define the joints constraints, the conditions for compatibility between elements were defined using a Boolean constant matrix. Computer processed results were verified by an experimental model.

Vehicle Steering Mechanism Elastodynamic Analysis

In this paper is performed an elasto-dynamic study of a steering mechanism from a road vehicle. Kinematical studies of the steering mechanism have been made especially on robots, their results being presented in scientific literature. The main purpose of this study is to reduce tires wear by optimizing the components of the steering mechanism.

3D Control for a Tronconic Tentacle

This paper deals with the control problem, simulation and implementation, for a class of hyper redundant manipulators – a tronconic tentacle arms. A tentacle robot produces changes of configuration using a continuous backbone made of sections which bend. A tentacle arm has a variable length and theoretically it can achieve any position and orientation in 3D space. A tentacle arm prototype was designed and the practical realization is now running. A solution for kinematics of this arm is presented.

Numerical Simulation of a Leg Exoskeleton for Human Motion Assistance

The objective of this paper is to validate the design of a leg exoskeleton used to aid persons with neuromotor disorders rehabilitation. The proposed design of the leg exoskeleton was performed in two stages. The first stage comprises the motion capture of 30 test subjects under normal walking conditions. An equipment for motion capture was used for this task, namely VICON. By using the obtained experimental data, a numerical simulation was computed in second stage for validating the leg exoskeleton proposed design. Finally, the results obtained from leg exoskeleton proposed design will allow improving rehabilitation therapies by reproducing different normal walking trajectories. The proposed solution shows a new mechanism design that combines capture motion data for synthesizing sprocket-mechanisms. The research also presents a new methodology to evaluate the design of a low-cost leg exoskeleton.

Dynamic Models for Analyzing a Self-propelled Vehicle for People with Locomotor Disabilities

In this paper there was made a virtual prototyping of a vehicle for servicing people with locomotor disabilities. This vehicle has as special components two differential transmissions that allow relatively easy optimization of the vehicle’s dynamic behavior. In addition to kinematic performance, this vehicle has a high degree of maneuverability as an important feature. Mathematical models for dynamic vehicle analysis are developed. Virtual prototyping involved designing the component parts that compose the component subassemblies. The main subassemblies are bevel gear differential transmissions, spur gear transmissions, worm gear drives from the traction and steering systems, including the shafts and housings of these subassemblies, the frame, as well as the propulsion train, all of those components are then assembled. The virtual prototype made in Solid Works is used to dynamically simulate in ADAMS of the assembly when running on a required trajectory. This vehicle is completed as an experimental model, being in the conception and implementation phase of the propulsion and steering control system.

Modelling and Control of a Mobile Robot, Equipped with an Arm in Cylindrical Coordinates with Uncoupled Tentacular Terminal

In this paper a robotic system which consists in a mobile platform with wheels and a robotic arm that operates in cylindrical coordinates which are located on, having a tentacular end-effector that executes specific grasping operations is presented. The robotic system executes: the displacement in the operation field, towards a target point that has been priori established, positioning the arm in order to perform the specified task, and the end-effector task according to a tentacular model. Kinematic models are made by Denavit – Hartenberg method and dynamic models by Lagrange method. Finally, is proposed a control system with uncoupled components.Keywords: mobile platform, tentacular structure, observer.

Evaluation and Improvement of Performance Parameters for a Mechanical System Used in Minirobotics

The concept, design and construction of mechanical systems performance is limited by the ranges prescribed for different performance parameters (size, accuracy, repeatability, quality, safety, and cost). The aim of the research is to evaluate and improve the performance parameters for a mechanical system with multiple vertebrae drive by wire, to perform functions of exploration, inspection and intervention in limited space environments (anatomical). New mechanical structure contains modules that allow changing the work parameter and the algorithms to control the location (position, orientation) of the end effector. Sensory system can be configured depending on the product and the program chosen, embracing suitable position, bending and strength sensors. Error compensation by a feedback process has become the most economical solution and easier to apply. Rigidity functions and bending forces resolution are presented along with a simulation of robotic arm positions for all vertebrae. The results demonstrate the capability of this system to perform precise movements to an imposed target.

Control by position sensors for a hyper-redundant robot

The paper treats the control problem for a class of hyper-redundant robots characterized by elastic backbone. The dynamic model of this system is analyzed. A measuring system based on curvature film sensors is proposed and an optical placement technique of sensors is discussed. A control algorithm is introduced by using the concept of boundary geometric control and a weighted state control method. Numerical simulations and experimental results illustrate the presented methods.

ARX Development for SQL Connection with Mechanical Desktop

Abstract The paper explores one of the most useful and interesting facilities for a CAD system: the bilateral relation with a database. This connection allows the development of a new tire in data management, establishing a permanent relation between graphic information (handled by a CAD system), and non graphic information (handled by a database manager). The novelty of the paper consists in exposing the internal mechanisms of data management, which are the basis of handling foreign data in Mechanical Desktop environment. All the considerations are done for version 6 of Mechanical Desktop, in connection with the version 15 of ARX library.

3D Control for a Truncated Cone Tentacle Kinematics

This paper presents the architecture, simulation, implementation and control problem for a class of continuum manipulators – the truncated cone tentacle arm. Desired shape for a tentacle robot is obtained by bending each of the three serial connected sections of a continuous backbone. Such tentacle arm has a fixed length but it can achieve any position and orientation in 3D space. A tentacle arm prototype was designed and the practical realization is now running. For this prototype we present a finite element model, for simulation purposes, we propose a kinematic model to be used in the control structure, and we conducted a series of tests regarding the structure behavior, using both sensor and artificial vision analysis. In this paper we present the results of our work.