7,333 research outputs found
Design an intelligent controller for full vehicle nonlinear active suspension systems
The main objective of designed the controller for a vehicle suspension system is to reduce the discomfort sensed by passengers which arises from road roughness and to increase the ride handling associated with the pitching and rolling movements. This necessitates a very fast and accurate controller to meet as much control objectives, as possible. Therefore, this paper deals with an artificial intelligence Neuro-Fuzzy (NF) technique to design a robust controller to meet the control objectives. The advantage of this controller is that it can handle the nonlinearities faster than other conventional controllers. The approach of the proposed controller is to minimize the vibrations on each corner of vehicle by supplying control forces to suspension system when travelling on rough road. The other purpose for using the NF controller for vehicle model is to reduce the body inclinations that are made during intensive manoeuvres including braking and cornering. A full vehicle nonlinear active suspension system is introduced and tested. The robustness of the proposed controller is being assessed by comparing with an optimal Fractional Order (FOPID) controller. The results show that the intelligent NF controller has improved the dynamic response measured by decreasing the cost function
Skyhook surface sliding mode control on semi-active vehicle suspension systems for ride comfort enhancement
A skyhook surface sliding mode control method was proposed and applied to the control on the semi-active vehicle suspension system for its ride comfort enhancement. A two degree of freedom dynamic model of a vehicle semi-active suspension system was given, which focused on the passengerâs ride comfort perform-ance. A simulation with the given initial conditions has been devised in MATLAB/SIMULINK. The simula-tion results were showing that there was an enhanced level of ride comfort for the vehicle semi-active sus-pension system with the skyhook surface sliding mode controller
Materials science and the sensor revolution
For the past decade, we have been investigating strategies to develop
ways to provide chemical sensing platforms capable of long-term
deployment in remote locations1-3. This key objective has been driven by
the emergence of ubiquitous digital communications and the associated
potential for widely deployed wireless sensor networks (WSNs).
Understandably, in these early days of WSNs, deployments have been
based on very reliable sensors, such as thermistors, accelerometers, flow
meters, photodetectors, and digital cameras. Biosensors and chemical
sensors (bio/chemo-sensors) are largely missing from this rapidly
developing field, despite the obvious value offered by an ability to measure
molecular targets at multiple locations in real-time. Interestingly, while
this paper is focused on the issues with respect to wide area sensing of
the environment, the core challenge is essentially the same for long-term
implantable bio/chemo-sensors4, i.e.; how to maintain the integrity of the
analytical method at a remote, inaccessible location
Active vibration control of flexible bodied railway vehicles via smart structures
Future railway vehicles are going to be designed lighter in order to achieve higher speed. Suppressing the flexible modes becomes a crucial issue for
improving the ride quality of the light-weight high speed railway vehicles. The concept of smart structure brings structural damping to flexible structures by integrating smart actuators and sensors onto the structure. Smart structure eliminates the need for extensive heavy mechanical actuation systems and achieves higher performance levels through their functionality for suppressing the flexible modes. Active secondary suspension is the
effective conventional approach for vibration control of the railway vehicle to improve the ride quality. But its ability in suppressing the flexible
modes is limited. So it is motivated to combine active structural damping
for suppressing the flexible modes and the vibration control through active secondary suspension which has an effect on both rigid and flexible modes.
The side-view model of the
flexible-bodied railway vehicle integrated with piezoelectric actuators and sensors is derived. The procedure for selection
of placement configurations of the piezoelectric actuators and sensors using structural norms is presented. Initial control studies show that the flexibility
of the vehicle body will cause a considerable degradation in ride quality if it is neglected in the design model. Centralized and decentralized control strategies with various control approaches (e.g. modal control with skyhook damping, LQG/H2 control, H_infinity control and model predictive control (MPC))are applied for the combined control of active structural damping
and active suspension control. The active structural damping effectively suppresses the flexible modes as a complement to the work of the active suspension control
Parylene-based electret power generators
n electret power generator is developed using a new electret made of a charged parylene HTÂź thin-film polymer. Here, parylene HTÂź is a room-temperature chemical-vapor-deposited thin-film polymer that is MEMS and CMOS compatible. With corona charge implantation, the surface charge density of parylene HTÂź is measured as high as 3.69 mC m^â2. Moreover, it is found that, with annealing at 400 °C for 1 h before charge implantation, both the long-term stability and the high-temperature reliability of the electret are improved. For the generator, a new design of the stator/rotor is also developed. The new micro electret generator does not require any sophisticated gap-controlling structure such as tethers. With the conformal coating capability of parylene HTÂź, it is also feasible to have the electret on the rotors, which is made of either a piece of metal or an insulator. The maximum power output, 17.98 ”W, is obtained at 50 Hz with an external load of 80 MΩ. For low frequencies, the generator can harvest 7.7 ”W at 10 Hz and 8.23 ”W at 20 Hz
Freeform Fabrication of Ionomeric Polymer-Metal Composite Actuators
Ionomeric polymer-metal composite (IPMC) actuators are a type of soft electromechanically active material which offers
large displacement, rapid motion with only ~1V stimulus. IPMCâs are entering commercial applications in toys (Ashley
2003) and biomedical devices (Soltanpour 2001; Shahinpoor 2002; Shahinpoor, Shahinpoor et al. 2003; Soltanpour and
Shahinpoor 2003; Soltanpour and Shahinpoor 2004), but unfortunately they can only actuate by bending, limiting their
utility. Freeform fabrication offers a possible means of producing IPMC with novel geometry and/or tightly integrated with
mechanisms which can yield linear or more complex motion. We have developed materials and processes which allow us to
freeform fabricate complete IPMC actuators and their fabrication substrate which will allow integration within other
freeform fabricated devices. We have produced simple IPMCâs using our multiple material freeform fabrication system, and
have demonstrated operation in air for more than 40 minutes and 256 bidirectional actuation cycles. The output stress scaled
to input power is two orders of magnitude inferior to that of the best reported performance for devices produced in the
traditional manner, but only slightly inferior to devices produced in a more similar manner. Possible explanations and paths
to improvement are presented. Freeform fabrication of complete electroactive polymer actuators in unusual geometries,
with tailored actuation behavior, and integrated with other freeform fabricated active components, will enable advances in
biomedical device engineering, biologically inspired robotics, and other fields. This work constitutes the first
demonstration of complete, functional, IPMC actuators produced entirely by freeform fabrication.Mechanical Engineerin
An effective strategy of real-time vision-based control for a Stewart platform
© 2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other worksA Stewart platform is a kind of parallel robot which can be used for a wide variety of technological and industrial applications. In this paper, a Stewart platform designed and assembled at the Universitat Polit`ecnica de Catalunya (UPC) by our research group is presented. The main objective is to overcome the enormous difficulties that arise when a real-time vision-based control of a fast moving object placed on these mechanisms is required. In addition, a description of its
geometric characteristics, the calibration process, together with an illustrative experiment to demonstrate the good behavior of the platform is given.Postprint (author's final draft
Piezoelectric vibration energy harvesting from airflow in HVAC (Heating Ventilation and Air Conditioning) systems
This study focuses on the design and wind tunnel testing of a high efficiency Energy Harvesting device, based on piezoelectric materials, with possible applications for the sustainability of smart buildings, structures and infrastructures. The development of the device was supported by ESA (the European Space Agency) under a program for the space technology transfer in the period 2014-2016. The EH device harvests the airflow inside Heating, Ventilation and Air Conditioning (HVAC) systems, using a piezoelectric component and an appropriate customizable aerodynamic appendix or fin that takes advantage of specific airflow phenomena (vortex shedding and galloping), and can be implemented for optimizing the energy consumption inside buildings. Focus is given on several relevant aspects of wind tunnel testing: different configurations for the piezoelectric bender (rectangular, cylindrical and T-shaped) are tested and compared, and the effective energy harvesting potential of a working prototype device is assessed
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