Design and application of electromechanical actuators for deep space missions

During the period 8/16/92 through 2/15/93, work has been focused on three major topics: (1) screw modeling and testing; (2) motor selection; and (3) health monitoring and fault diagnosis. Detailed theoretical analysis has been performed to specify a full dynamic model for the roller screw. A test stand has been designed for model parameter estimation and screw testing. In addition, the test stand is expected to be used to perform a study on transverse screw loading

Ground Robotic Hand Applications for the Space Program study (GRASP)

This document reports on a NASA-STDP effort to address research interests of the NASA Kennedy Space Center (KSC) through a study entitled, Ground Robotic-Hand Applications for the Space Program (GRASP). The primary objective of the GRASP study was to identify beneficial applications of specialized end-effectors and robotic hand devices for automating any ground operations which are performed at the Kennedy Space Center. Thus, operations for expendable vehicles, the Space Shuttle and its components, and all payloads were included in the study. Typical benefits of automating operations, or augmenting human operators performing physical tasks, include: reduced costs; enhanced safety and reliability; and reduced processing turnaround time

DESIGN AND FABRICATION OF WIRELESS OPERATED PAINTBALL ROBOT FOR MIROC 2014 COMPETITION

The purpose of this project is to design and fabricate a wireless operated paintball robot for MIRoC 2014 competition. The previous paintball robot built has some technical issues, in which the driving mechanism applied are less maneuverable and it has bulky chassis design which increases the chance of being hit by another robot in the competition. In this project, the focus is to perform improvements on the paintball robot in terms of its driving mechanism and the chassis based on previous paintball robot. For the driving mechanism, Mecanum driving mechanism has been applied to the robot. The Mecanum driving mechanism mixer circuit is designed and simulated using Multisim and fabricated for application in the field. For the chassis improvement, the new designed chassis has lower height which reduces the chance of being hit. The design was made using SketchUp Pro. The performance of the robot is determined by its maneuverability and simplicity of the control in reference to its predecessors. The results show that the fabricated robot has achieved higher maneuverability rate and have smaller chassis size, which is advantageous in the competition later. In conclusion, the project is successful as it has achieved its main objectives stated earlier. In the future, the result of this project can be replicated to be used for other purpose in other fields

Implementation of an attitude control board for CubeSat on one axis with inertial wheel activated by brushless motor

The following work belongs to the PLATHON project (PLATform of integrated simulation of Hardwar in the loop for Optical communications in Nanosatellites), conducted by the research group led by Dr. Javier Gago and Dr. David González at the Polytechnic University of Catalonia in Terrassa, ESEIAAT (Superior School of Industrial, Audiovisual, and Aeronautical Engineering of Terrassa). The main objective of PLATHON is to replicate a network system composed of CubeSats, which collect data and establish communication with various satellites in orbit. The project heavily relies on the participation of final-year undergraduate and master's degree students from different departments, who contribute significantly to its development. Specifically, this project consists of developing a method to obtain attitude control of the CubeSat using reaction wheels, with performance similar to commercial solutions. In addition to cost reduction, certain aspects will also be improved or adapted for the final implementation in the CubeSat. The methodology followed by this project is based on the research and application of theoretical statements for the operation of BLDC motors. Moreover, having access to the UPC facilities in Terrassa has allowed us to experience each situation in the laboratory and make informed decisions. Finally, the achieved result is a closed-loop voltage control that allows a range of motor speeds and depends on the input voltage. Furthermore, a printed circuit board has been developed to apply a sensing method based on Hall effect sensors. On the other hand, there have been some limitations, all of which are due to the small size of the BLDC motor used, a characteristic that has influenced most of the project's decisions. Nevertheless, this project can be used as a research foundation or as a starting point for other projects

Energy-oriented Modeling And Control of Robotic Systems

This research focuses on the energy-oriented control of robotic systems using an ultracapacitor as the energy source. The primary objective is to simultaneously achieve the motion task objective and to increase energy efficiency through energy regeneration. To achieve this objective, three aims have been introduced and studied: brushless DC motors (BLDC) control by achieving optimum current in the motor, such that the motion task is achieved, and the energy consumption is minimized. A proof-ofconcept study to design a BLDC motor driver which has superiority compare to an off-the-shelf driver in terms of energy regeneration, and finally, the third aim is to develop a framework to study energy-oriented control in cooperative robots. The first aim is achieved by introducing an analytical solution which finds the optimal currents based on the desired torque generated by a virtual. Furthermore, it is shown that the well-known choice of a zero direct current component in the direct-quadrature frame is sub-optimal relative to our energy optimization objective. The second aim is achieved by introducing a novel BLDC motor driver, composed of three independent regenerative drives. To run the motor, the control law is obtained by specifying an outer-loop torque controller followed by minimization of power consumption via online constrained quadratic optimization. An experiment is conducted to assess the performance of the proposed concept against an off-the-shelf driver. It is shown that, in terms of energy regeneration and consumption, the developed driver has better performance, and a reduction of 15% energy consumption is achieved. v For the third aim, an impedance-based control scheme is introduced for cooperative manipulators grasping a rigid object. The position and orientation of the payload are to be maintained close to a desired trajectory, trading off tracking accuracy by low energy consumption and maintaining stability. To this end, an optimization problem is formulated using energy balance equations. The optimization finds the damping and stiffness gains of the impedance relation such that the energy consumption is minimized. Furthermore, L2 stability techniques are used to allow for time-varying damping and stiffness in the desired impedance. A numerical example is provided to demonstrate the results

Model-Based Fault Detection and Identification for Prognostics of Electromechanical Actuators Using Genetic Algorithms

Traditional hydraulic servomechanisms for aircraft control surfaces are being gradually replaced by newer technologies, such as Electro-Mechanical Actuators (EMAs). Since field data about reliability of EMAs are not available due to their recent adoption, their failure modes are not fully understood yet; therefore, an effective prognostic tool could help detect incipient failures of the flight control system, in order to properly schedule maintenance interventions and replacement of the actuators. A twofold benefit would be achieved: Safety would be improved by avoiding the aircraft to fly with damaged components, and replacement of still functional components would be prevented, reducing maintenance costs. However, EMA prognostic presents a challenge due to the complexity and to the multi-disciplinary nature of the monitored systems. We propose a model-based fault detection and isolation (FDI) method, employing a Genetic Algorithm (GA) to identify failure precursors before the performance of the system starts being compromised. Four different failure modes are considered: dry friction, backlash, partial coil short circuit, and controller gain drift. The method presented in this work is able to deal with the challenge leveraging the system design knowledge in a more effective way than data-driven strategies, and requires less experimental data. To test the proposed tool, a simulated test rig was developed. Two numerical models of the EMA were implemented with different level of detail: A high fidelity model provided the data of the faulty actuator to be analyzed, while a simpler one, computationally lighter but accurate enough to simulate the considered fault modes, was executed iteratively by the GA. The results showed good robustness and precision, allowing the early identification of a system malfunctioning with few false positives or missed failures.https://susy.mdpi

Multi-physics Model Of Key Components In High Efficiency Vehicle Drive

Hybrid Electric Vehicles (HEVs) and Electric Vehicles (EVs) are crucial technologies for the automotive industry to meet society’s demands for cleaner, more energy efficient transportation. Meeting the need to provide power which sustains HEVs and EVs is an immediate area of concern that research and development within the automotive community must address. Electric batteries and electrical motors are the key components in HEV and EV power generation and transmission, and their performance plays very important role in the overall performance of the modern high efficiency vehicles. Therefore, in this dissertation, we are motivated to study the electric batteries, interior permanent motor (IPM), in the context of modern hybrid electric/electric drive systems, from both multi-physics and system level perspectives. Electrical circuit theory, electromagnetic Finite Element Analysis (FEA), and Computational Fluid Dynamic (CFD) finite volume method will be used primarily in this work. The work has total of five parts, and they are introduced in the following. Firstly, Battery thermal management design is critical in HEV and EV development. Accurate temperature distribution of the battery cells during vehicle operation is required for achieving optimized design. We propose a novel electrical-thermal battery modeling technique that couples a temperature dependent battery circuit model and a physics-based CFD model to meet this need. The electrical circuit model serves as a heat generation mechanism for the CFD model, and the CFD model provides the temperature distribution of the battery cells, which can also impact the heat generation of the electrical battery model. In this part of work, simulation data has been derived from the model respective to electrical performance of the battery as well iv as the temperature distribution simultaneously in consideration of the physical dimensions, material properties, and cooling conditions. The proposed model is validated against a battery model that couples the same electrical model with a known equivalent thermal model. Secondly, we propose an accurate system level Foster network thermal model. The parameters of the model are extracted from step responses of the CFD battery thermal model. The Foster network model and the CFD model give the same results. The Foster network can couple with battery circuit model to form an electric-thermal battery model for system simulation. Thirdly, IPM electric machines are important in high performance drive systems. During normal operations, irreversible demagnetization can occur due to temperature rise and various loading conditions. We investigate the performance of an IPM using 3d time stepping electromagnetic FEA considering magnet’s temperature dependency. Torque, flux linkage, induced voltage, inductance and saliency of the IPM will be studied in details. Finally, we use CFD to predict the non-uniform temperature distribution of the IPM machine and the impact of this distribution on motor performance. Fourthly, we will switch gear to investigate the IPM motor on the system level. A reduced order IPM model is proposed to consider the effect of demagnetization of permanent magnet due to temperature effect. The proposed model is validated by comparing its results to the FEA results. Finally, a HEV is a vehicle that has both conventional mechanical (i.e. internal combustion engine) and electrical propulsion systems. The electrical powertrain is used to work with the conventional powertrain to achieve higher fuel economy and lower emissions. v Computer based modeling and simulation techniques are therefore essential to help reduce the design cost and optimize system performance. Due to the complexity of hybrid vehicles, multidomain modeling ability is preferred for both component modeling and system simulation. We present a HEV library developed using VHDL-AMS

Wear-Resistant Extrusion Auger for the Production of Charcoal Briquettes from Agricultural Waste

Ugandan social enterprise AEST makes and sells agricultural waste charcoal briquettes. The extrusion auger used wore down quickly, hampering production. The team worked to find a better material or heattreatment process to improve the auger\u27s lifetime. The team built a custom pin-on-disk testing apparatus and used it along with optical microscopy to analyze the wear mechanism. The team then heat-treated and tested additional samples to find the best treatment. The team suggested improving AEST’s current case hardening process by increasing the case depth to 0.04 in (0.1016 cm) and using oil quenching

Conceptual design study for a teleoperator visual system, phase 2

An analysis of the concept for the hybrid stereo-monoscopic television visual system is reported. The visual concept is described along with the following subsystems: illumination, deployment/articulation, telecommunications, visual displays, and the controls and display station