Ahmed A. Ramadan

Developmental Process of a Chopstick-Like Hybrid-Structure Two-Fingered Micromanipulator Hand for 3-D Manipulation of Microscopic Objects

The development of a chopstick-like two-fingered micromanipulator based on a hybrid mechanism is presented. The microhand consists of two 3-prismatic-revolute-spherical (PRS) parallel modules connected serially in a mirror image style. Each module has a long glass pipette as an end effector. The development process consists of three phases. In the first phase, analysis and mathematical modeling, a novel solution of the inverse kinematics problem (IKP) of a 3-revolute-prismatic-spherical (RPS) parallel module, is derived and applied with proper modification to the case of 3-PRS of the proposed mechanism. The solution is extended to the two-fingered hybrid mechanism of the microhand. In the optimization and design phase, the optimization of the chosen design parameters of a theoretical 3-PRS parallel module is carried out using two approaches: discretization method and genetic algorithms. Based on the optimal design parameters, a CAD model of the 3-PRS finger module is built, and a complementary optimization step using the ANSYS Workbench program is carried out to determine suitable characteristics of the pin flexure hinge. Finally, the total CAD model of the two-fingered hand is built. In the realization and implementation phase, the description of the hardware system of the two-fingered microhand prototype is presented. The program description, calibration method, practical Jacobian matrices, practical workspace, and error analysis of the prototype are discussed.

Modeling and control of a new quadrotor manipulation system

This paper introduces a new quadrotor manipulation system that consists of a 2-link manipulator attached to the bottom of a quadrotor. This new system presents a solution for the drawbacks found in the current quadrotor manipulation system which uses a gripper fixed to a quadrotor. Unlike the current system, the proposed system enables the end-effector to achieve any arbitrary orientation and thus increases its degrees of freedom from 4 to 6. Also, it provides enough distance between the quadrotor and the object to be manipulated. This is useful in some applications such as demining applications. System kinematics and dynamics are derived which are highly nonlinear. Controller is designed based on feedback linearization to track desired trajectories. Controlling the movements in the horizontal directions is simplified by utilizing the derived nonholonmic constraints. Finally, the proposed system is simulated using MATLAB/SIMULINK program. The simulation results show the effectiveness of the proposed controller.

New Architecture of a Hybrid Two-Fingered Micro–Nano Manipulator Hand: Optimization and Design

This paper presents the synthesis and design optimization of a compact and yet economical hybrid two-fingered micro–nano manipulator hand. The proposed manipulator hand consists of two series modules, i.e., an upper and lower modules. Each of them consists of a parallel kinematics chain with a glass pipette (1 mm diameter and 3–10 cm length) tapered to a very sharp end as an end-effector. It is driven by three piezo-electric actuated prismatic joints in each of the three legs of the parallel kinematics chain. Each leg of the kinematics chain has the prismatic–revolute–spherical joint structure. As the length of the glass pipette end-effector is decreased, the resolution and accuracy of the micro–nano manipulator hand is increased. For long lengths of the glass pipette end-effector, this manipulator works as a micro manipulator and for short lengths it works as a nano manipulator. A novel closed-form solution for the problem of inverse kinematics is obtained. Based on this solution, a simulation program has been developed to optimally choose the design parameters of each module so that the manipulator will have a maximum workspace volume. A computer-aided design model based on optimal parameters is built and investigated to check its workspace volume. Experimental work has been carried out for the purpose of calibration. Also, the system hardware setup of the hybrid two-fingered micro–nano manipulator hand and its practical Jacobian inverse matrices are presented.

Methodology for identifying quadrotor parameters, attitude estimation and control

This paper describes a methodology to identify all the parameters of a quadrotor system including the structure parameters and rotor assembly parameters. A CAD model is developed using SOLIDWORKS to calculate the mass moment of inertia and all the missing geometrical parameters. A three simple test rigs are built and used to identify the relationship between the motor input Pulse Width Modulation (PWM) signal and the angular velocity, the thrust force, and drag moment of the rotors. A simple algorithm is implemented to an inertial measurement unit (IMU) for estimating the attitude and altitude of the quadrotor. Experimental set up is built to verify and test the accuracy of these proposed techniques. A controller is designed based on the feedback linearization method such that the quadrotor attitude can be stabilized. Finally, the experimental results show the effectiveness of the proposed techniques and the controller design.

Design Optimization of a Compact 3-DOF Parallel Micro/Nano Finger Manipulator

A compact and yet economical 3-DOF micro/nano finger manipulator based on micro parallel kinematics structure is presented in this paper. It uses three piezo-electric actuators and two types of flexure joints, one is a revolute joint and the other is a ball joint, as its main mechanism. The problem of inverse kinematics between end effector position and actuator displacements along with the Jacobian matrix for this design is derived. A glass needle of 3 to 10 cm length is used as the end effector to increase the workspace of the micro/nano manipulator. As the length of the glass needle end effector is decreased, the resolution and accuracy of the manipulator is increased while the workspace volume is decreased. The design parameters are optimally chosen so that the manipulator will obtain maximum workspace volume. The simulation results illustrate that the proposed model has a large workspace and in the same time it will be small in size using the proposed architecture

New Design of a Compact Parallel Micro-Nano Two-Fingered Manipulator Hand

This paper presents the analysis and design optimization of a new compact and yet economical micro-nano two-fingered manipulator hand. The proposed manipulator hand consists of two series modules; upper and lower module. Each module consists of a parallel kinematics chain with a glass pipette of 3 to 10 cm length as an end effector. It is driven by three piezoelectric actuated prismatic joints in each of the three legs of the kinematics chain. Each leg of the kinematics chain has the structure of prismatic-revolute-socket ball (PRS) joints structure. As the length of the glass pipette end effector is decreased, the resolution and accuracy of the micro-nano manipulator hand is increased. A new solution for the problem of inverse kinematics is obtained. Based on this solution, a simulation program has been developed to optimally choose the design parameters of each module so that the manipulator have a maximum workspace volume. Also the manipulator hand is small in size due to the proposed architecture.

Development of parallel manipulator sit to stand assistive device for elderly people

This paper describes a novel mobility assistive device under development in the Egypt-Japan University of Science and Technology (E-JUST). The proposed system can help patients who do not have enough physical strength on the lower limbs during sit to stand due to aging, diseases such as polymyositis and myopathy, and joint replacement surgery complications. It can follow the natural pattern of human motion during sit to stand providing assistance force under the shoulder. The overall device is compact and employees a parallel mechanism which provide more stiffness. Several experiments were carried out in a VICON room to calculate the human motion posture while sit to stand motion in addition estimate the trajectory of the end effector during assisting. Computer simulation was built to verify the performance of the proposed system with the reference trajectory.

New Hybrid Two-Fingered Micro-Nano Manipulator Hand: Optimization and Design

In this paper, the structure of a new compact and yet economical two-fingered micro-nano hybrid manipulator hand is presented. The hybrid manipulator hand consists of two series modules; upper and lower module. Each of them consists of a parallel kinematics chain with a glass pipette as an end effector. It is driven by three piezo-electric actuated prismatic joints in each of the three legs of the parallel kinematics chain. Each leg has the structure of prismatic-revolute-spherical (PRS) joint structure. As the length of the glass pipette end effector is decreased, the resolution and accuracy of the micro-nano manipulator hand is increased. For long lengths of glass pipette end effector, this manipulator works as micro-manipulator and it works as nano-manipulator for short lengths. A solution for the inverse kinematics problem of the complete mechanism is obtained. Based on this solution, a simulation program has been developed to optimally choose the design parameters so that the mechanism will have a maximum workspace volume. A proposed computer aided design (CAD) model based on optimal parameters is built and realized. Also the system hardware setup of the micro-nano hand and its practical Jacobian is presented.

Evaluation of a proposed workspace spanning technique for small haptic device based manipulator teleoperation

This paper presents an evaluation of a new proposed workspace spanning technique for master/slave system teleoperation which is still a challenging task. This new technique integrates position control and a modified rate control methods to solve the problem of workspace mapping of two kinematically dissimilar robots used in teleoperation system. The slave device is having a large workspace in most cases while the master device is usually having a physically limited workspace. The workspace mapping of a small haptic device based robot should be handled carefully without disturbing the user perception of continuous teleoperating the robot movement in a natural and precise way. The proposed technique referred to as Positioning with Modified Rate Control is simple and overcomes the drawbacks of other techniques like indexing, rate control, ballistic control, and drift control. It depends on switching between rate control with constant speed for coarse motion and position control for accurate movements. Experimental setup based on phantom premium haptic device as a master and RV-2AJ Mitsubishi robot arm as a slave is used to evaluate the feasibility of the proposed technique. Experimental results demonstrate that the operator can easily navigate through the whole workspace of an industrial robot using a small haptic device while achieving accurate positioning. Besides, the proposed technique is judged against the scaling technique in performing a prescribed task to evaluate its performance.

Fuzzy-based gain scheduling of Exact FeedForward Linearization control and sliding mode control for magnetic ball levitation system: A comparative study

This paper presents a comparative study between two control approaches; an Exact FeedForward Linearization controller developed by fuzzy-gain scheduling and sliding mode controller based on Ackermann and Utkin method. For the later one the sliding surface dynamics are determined explicitly without transforming to the sliding mode canonical form. The benefits of this study are demonstrated practically on a well known benchmark control problem, Magnetic ball levitation system (Maglev), and the performances of both controllers are compared. Important control issues such as tracking ability, control effort, steady state error and noise rejection are experimentally investigated.