Mircea Ivanescu

A variable structure controller for a tentacle manipulator

The paper presents a class of tentacle arms based on the use of flexible composite materials in conjunction with active-controllable electrorheological (ER) fluids. The model consists of a finite number of segments, each segment having a specific structure and control. The dynamic behaviour of the arm is obtained using Lagranges principle developed for infinite-dimensional systems. This model is represented by a set of integral-differential equations. An approximate model is then derived as a set of differential equations with variable coefficients. Two cases are discussed: the sliding mode with the bang-bang control; and the direct mode in which the controller is based on the use of the direct evolution of the system on the switching line by switching the fluid viscosity. The numerical simulations are presented. A nonlinear observer is introduced to estimate the inaccessible state variable distributed on the length of the arm. The conditions which assure the convergence to zero of the errors are proved.

Position dynamic control for a tentacle manipulator

The control problem of the spatial tentacle manipulator is presented. The difficulties determined by the complexity of the nonlinear integral-differential equations are avoided by using a very basic energy relationship of this system. Energy-based control laws are introduced by using only the relations that determine the energy stored in the system. A PD controller and a fuzzy controller are discussed. Numerical simulations for spatial and planar tentacle models are presented in order to prove the efficiency of the method.

A Variable Length Tentacle Manipulator Control System

The control problem of a class of tentacle arm, with variable length, that can achieve any position and orientation in 3D space and can increase the length in order to get a better control in the constraint operator space is presented. First, the dynamic model of the system is inferred. In order to avoid the difficulties generated by the complexity of the nonlinear integral - differential model, the control problem is based on the artificial potential method. Then, the method is used for constrained motion in an environment with obstacles. Numerical simulations for spatial and planar tentacle models are presented in order to illustrate the efficiency of the method.

Dynamic control for a tentacle manipulator with SMA actuators

The control problem of the spatial tentacle manipulator with SMA control is presented. The difficulties determined by the complexity of the nonlinear integral-differential equations are avoided by using a very basic energy relationship of this system. A PD controller is discussed and a control coefficient selection procedure is introduced. Numerical simulations for planar and spatial tentacle models are presented and an experimental model is discussed.

Frequency criteria for the grasping control of a hyper-redundant robot

The paper focuses on hyper-redundant arms with continuum elements that perform the grasping function by coiling. First, there is concern with the dynamic model of the continuum arm for the position control during non-contact operations with the environment. A frequency stability criterion based on the Kahman - Yakubovich - Popov Lemma and P and PD control algorithms is proposed. Then, the grasping control of the arm in contact with a load is analyzed. The dynamics of the system are discussed and an extension of the Popov criterion is endorsed. The control algorithms based on SMA actuators are introduced. Numerical simulations and experimental results of the arm motion toward an imposed target are presented.

A sequential distributed variable structure controller for a tentacle arm

The paper presents a new controller for a tentacle arm based on the viscosity control of the ER-fluids by an electrical field. The dynamic model of the arm is determined and an approximate model is proposed. The motion control is determined as a conventional control of the fluid pressure and as a viscosity control on the switching manifolds. The stability of the motion is proved and the conditions of the trajectory control on the switching manifolds are determined. Two viscosity control procedures are used: a lumped control and a sequential distributed control which allows the decomposition of the system in a finite number of a lower dimension problems. The numerical simulations are presented.

Position and force control of the grasping function for a hyperredundant arm

The grasping control problem for a hyperredundant manipulator is presented. The dynamic model is derived by using Lagrange equations developed for infinite dimensional systems. The algorithms for the position and force control are proposed. The arm fluid pressure control is inferred and the conditions that ensure the stability of the motion are discussed. Numerical simulations are presented.

Force observer-based control for a rehabilitation hand exoskeleton system

This paper is a component of a research project regarding the design and development of an Intelligent Haptic Robot-Glove for the rehabilitation of the patients that have a diagnosis of a cerebrovascular accident. In this paper, the control system for a rehabilitation hand exoskeleton is discussed. In order to avoid the complex problems given by a distributed sensor network, this paper treats the problem of the compliance force control by using observers: a velocity observer, a force observer and a disturbance observer. Two control solutions are discussed. First, the disturbance effects are eliminated by a cascade closed loop control with velocity and force observers. Then, a disturbance observer is used to compensate the compliance effects. The performance of the control systems is demonstrated by the simulation.

Using Artificial Potential Field Methods and Fuzzy Logic for Mobile Robot Control

This paper presents a new control method for mobile robots moving in its work field which is based on fuzzy logic and artificial potential field. First, the artificial potential field method is presented. The paper treats unconstrained movement based on attractive artificial potential field and after that discuss the constrained movement based on attractive and repulsive artificial potential field. A fuzzy controller is designed. Finally, some applications are presented.

A decoupled sliding mode control for a continuum arm

The paper treats the control problem of a class of robots constituted by a chain of continuum segments. The technological model basis is a central, long and thin, highly flexible and elastic backbone. The segment control system is a decoupled one. The main parameters of the arm control are determined by the curvature and curvature gradient. The dynamic model is inferred. The primary benefit of the proposed method is that the dynamic equations are represented by a set of ODE’s in time instead of PDE’s in time and space, and the new curvature gradient lumped parameter model is used. A sliding mode control system is used in order to achieve the desired shape of the arm. The stability of the closed-loop control system is proven. Numerical simulations and an experimental platform are also provided to verify the effectiveness of the presented approach.