Mihaela Florescu

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.

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.

Role Selection Mechanism for the Soccer Robot System using Petri Net

Robot soccer is a challenging platform for multi-agent research, involving topics such as real-time image processing and control, robot path planning, obstacle avoidance and machine learning. The system consists of a supervisory controller, and controllers for defending and goalkeeping robots. These controllers are designed using Petri net. The robot soccer game presents an uncertain and dynamic environment for cooperating agents. Dynamic role switching and formation control are crucial for a successful game. A soccer robot has to take an appropriate decision based on environment situation. With the role of a robot fixed as goalkeeper, the supervisor, according to the game situation, assigns the role of attacking or defending to the other robots and then respective controllers control the robots. The Petri net model is implemented in Petri net toolbox under MATLAB environment.

Coil function control problem for a hyperredundant robot

The paper focuses on the control problem of a hyperredundant robot that performs the coil function of grasping. First, the dynamic model of a hyperredundant arm with continuum elements produced by flexible composite materials in conjunction with active-controllable electro-rheological fluids is analyzed. Secondly, both problems, i.e. the position control and the force control are approached. The difficulties determined by the complexity of the non-linear integral-differential equations are avoided by using a basic energy relationship of this system. Energy-based control laws are introduced for the position control problem. A force control method is proposed, namely the DSMC method in which the evolution of the system on the switching line by the ER fluid viscosity is controlled. Numerical simulations are also presented.

Control System for a Hyper-Redundant Robot

Abstract Command and control system of a hyper-redundant robot is presented in this paper. Hyper-redundant robots are a new class of robots designed with a large number of joints with high degree of mobility, in order to operate in areas with restrictions. The robot presented in this paper is a hyper-redundant robot elephant trunk type with truncated cone structure. Flexible structure is made of two independent modules that drive, bending robot is made by nature. Drive block for each module consists of two stepper motors that allow bending toward the axes X and Y. The transmission and engine to convert the movement of flexible modules are achieved through a reduction gear assembly and sheaves. Each module consists of 4(5) flexible items. Each element is driven by four cables (one pair for each axis). Separate drive of each element of flexible module provides a very good control of the distribution of forces, and curvature. The control system is built on a 32-bit PIC microcontroller. Control algorithm allows the motor control by microsteps using integrated PWM voltage generator. The law of motion is given by a fuzzy algorithm which optimizes the parameters of movement. For kinematic simulation, the model of the robot was made in Solidworks CAD environment, achieving a parametric animation.

A Distributed Force and Position Control for Tentacle Manipulator

Abstract The grasping control problem for a hyperredundant arm is studied. Frist, dynamic model of the arm is analyzed. The control problems are divided in the subproblems: the position control in a desired reaching area, the control of the arm around the object-load and the force control of grasping. The difficulties determined by the complexity of the non-linear integral-differential equations are avoided by using a very basic energy relationship of this system. First, the dynamic control of the arm for a desired reaching area is inferred. Then, the position controland the force control for grasping are discussed. Numerical simulation are presented.

Force control of grasping operation for a tentacle robot

The paper treats a class of hyper-redundant robots with continuous elements, which performs the function of grasping by coil. First, the dynamic model of the system is deduced. Laws of control are introduced based on the systems energy for force control problem. It is proposed a method of controlling the force using the DSMC method, showing the evolution of the system on the switching line by controlling the electro-rheological fluids viscosity.

Control of Snake Type Biomimetic Structure

Robotic cooperative tasks impose, in many cases, a grasping action. Grasping by coiling it is one of the most versatile action. The present article propose a frequency stability criterion based on the Kahman – Yakubovich – Popov Lemma for the hyper-redundant arms with continuum element that performs the grasping function by coiling. Dynamics of the biomimetical robot during non-contact and contact operations, for the position control, is studied. An extension of the Popov criterion is developed. The P control algorithms based on SMA snake-type robot actuators are introduced. Numerical simulations and experimental results of the snake type robot motion toward an imposed target are presented.

Hybrid Control Strategies for Jumping Robots

The paper treats the control problem of the locomotion phases in a jumping cycle of a robot. The mechanical architecture of the leg with elastic lower segment (ATHLETE MODEL) is discussed. The dynamic model of the motion in stance phase is determined. The touch-down sequence, when the elastic foot hits the ground, is discussed and the control system is analyzed for two cases: actuator as passive damper system and actuator as semi-active damper system with ground-hook damper model. The transmissibility characteristics are analyzed. An active damper with ER fluids actuator and a skyhook viscosity controller is proposed to avoid the vibrations in the mechanical structure that can disturb the evolution of the robot. The control parameters are determined by using the circle criterion. The take-off sequence conditions in the stance phase are inferred by using the energy concept.

Dynamic Control for a Class of Continuum Robotic Arms

The paper deals with the control problem of a class of hyper-redundant robots constituted by a chain of continuum segments. The main parameter, the system state, is determined by the position and velocity generalised variables. The dynamic model is studied and the constraints of the state variables and nonlinear components are proved. The observability problems are solved by an approach derived from the Luenberger observer type extended for this class of non-linear distributed models. The inequality constraints on the gravitational components allow to introduce a decoupled control system. A PD boundary control algorithm is used in order to achieve a desired shape of the arm. The stability analysis and the resulting controllers are obtained using Liapunov techniques. The exponential stability of the (error-observer) system was proved. The constraints on the observer and controller gains are analysed. Experimental tests verify the effectiveness of the presented techniques.