Design process and simulation testing of a shape memory alloy actuated robotic microgripper

Microgrippers are commonly used for micromanipulation of micro-objects with dimensions from 1 to 100 µm and attain features of reliable accuracy, low cost, wide jaw aperture and variable applied force. This paper studies the design process, simulation, and testing of a microgripper which can manipulate and assemble a platinum resistance temperature probe, made from a 25 µm diameter platinum wire, a 20 mm diameter tinned copper wire, and a printed circuit board type connector. Various microgripper structures and actuator types were researched and reviewed to determine the most suitable design for the required micromanipulation task. Operation tests using SolidWorks and ANSYS software were conducted to test a parallelogram structure with flexible single-notch hinges. The best suited material was found to be Aluminium alloy 7075-T6 as it was capable of producing a large jaw tip displacement of 0.7 mm without exceeding its tensile yield strength limit. A shape memory alloy was chosen as a choice of actuator to close the microgripper jaws. To ensure a repeatably accurate datum point, the final microgripper consisted of a fixed arm and a flexible arm. An optimisation process using ANSYS studied the hinge thickness and radius dimensions of the microgripper which improved its deflection whilst reducing the experienced stress

High-Fidelity Hardware-in-Loop Simulation of Tethered-Wings Based on Discrete-Time Mechanics

MATLAB files for recreation of a HIL setup in a simulation environment. Use Matlab 2017b or later to run the simulation. Execute Simulation.m to start simulation.THIS DATASET IS ARCHIVED AT DANS/EASY, BUT NOT ACCESSIBLE HERE. TO VIEW A LIST OF FILES AND ACCESS THE FILES IN THIS DATASET CLICK ON THE DOI-LINK ABOV

Optimal balancing of robot manipulators in point-to-point motion

SUMMARYIn this paper, a new balancing approach called “optimal balancing” is presented for open-chain robot manipulators based on open-loop optimal control. In fact, an optimal trajectory planning problem is outlined in which states, controls and the values of counterweights must be determined simultaneously in order to minimize the given performance index for a predefined point-to-point task. Optimal balancing method can be propounded beside the other methods such as unbalancing, static balancing and adaptive balancing, with this superiority that the objective criterion value obtained of proposed method is very lower than the objective criterion value obtained of other methods. For this purpose, the optimal control problem is extended to the case where the performance index, the differential constraints and the prescribed final conditions contain parameters. Using the fundamental theorem of calculus of variations, the necessary conditions for optimality are derived which lead to the optimality conditions associated with the Pontryagin's minimum principle and an additional condition associated with the constant parameters. By developing the obtained optimality conditions for the two-link manipulator, a two-point boundary value problem is achieved which can be solved with bvp4c command in MATLAB®. The obtained results show that optimal balancing in comparison with the previous methods can reduce the performance index significantly. This method can be easily applied to the more complicated manipulator such as a three degrees of freedom articulated manipulator.</jats:p

Deriving and analyzing the effective parameters in microgrippers performance

AbstractThe microgripper is a Micro-Electro-Mechanical System (MEMS) with the ability to handle and manipulate micron or sub micron objects precisely. They have many applications in micro assembly, biology, tissue engineering and so on. In this paper, the effective parameters on the performance and designing of the microgrippers are derived by reviewing and comparing their different types. These parameters are: material specification, displacement amplification factor, gripping range and stroke, jaw motion characteristic, normally open and normally closed gripper, ideal shape of tips, aspect ratio, number of degree of freedom and micro actuator specifications. These parameters are introduced and their influences on gripper performance are studied. Knowing all the effective parameters and analyzing the effect of each parameter on micro gripper performance is the first step towards design of new optimized microgrippers. Finally, an overall algorithm to design the microgripper is proposed

Optimal spring balancing of robot manipulators in point-to-point motion

SUMMARYThe balancing of robotic systems is an important issue, because it allows significant reduction of torques. However, the literature review shows that the balancing of robotic systems is performed without considering the traveling trajectory. Although in static balancing the gravity effects on the actuators are removed, and in complete balancing the Coriolis, centripetal, gravitational, and cross-inertia terms are eliminated, but it does not mean that the required torque to move the manipulator from one point to another point is minimum. In this paper, “optimal spring balancing” is presented for open-chain robotic system based on indirect solution of open-loop optimal control problem. Indeed, optimal spring balancing is an optimal trajectory planning problem in which states, controls, and all the unknown parameters associated with the springs must be determined simultaneously to minimize the given performance index for a predefined point-to-point task. For this purpose, on the basis of the fundamental theorem of calculus of variations, the necessary conditions for optimality are derived that lead to the optimality conditions associated with Pontryagin's minimum principle and an additional condition associated with the constant parameters. The obtained optimality conditions are developed for a two-link manipulator in detail. Finally, the efficiency of the suggested approach is illustrated by simulation for a two-link manipulator and a PUMA-like robot. The obtained results show that the proposed method has dominant superiority over the previous methods such as static balancing or complete balancing.</jats:p