Active Electromagnetic Damping for Lightweight Electric Vehicles.

Due to the low weight of most current electric vehicles, the effectiveness of commercial passive dampers is reduced when compared to current production automobiles. Active dampers allow for a significant reduction in the amount of road signal that affects the passenger body. However current active hydraulic dampers tend to be heavy and to have a power consumption that precludes their use in electric vehicles. By use of a linear electromagnetic element it is possible to create an active damper that has enough authority to provide active damping with a fraction of the weight and power consumption of a hydraulic system. A computer model of an active electromagnetic damper was constructed and the results were compared to a physical prototype. This verified the effectiveness of the damper and the low power consumption. This computer model was then scaled up for the simulation of a real world quarter car model. This simulation demonstrated that the use of the active linear electromagnetic damper was more effective at all frequencies when compared to an ideal passive damper. It was also demonstrated that the active electromagnetic damper had a similar mass to a passive damper and had a power consumption of more than an order of magnitude less than a comparable active hydraulic damper. Keywords-component; Electromagnetic; damping; active; suspension

Investigation into low power active electromagnetic damping for automotive applications

Automobile suspension systems carry out two important functions; road handling and passenger comfort. Hydraulic passive dampers are the most common system employed on vehicles, yet it is well known that passive suspension systems are less effective on lightweight vehicles. Modern damper technologies such as semi-active and active dampers, offer potential benefits when used in these vehicles. An active electromagnetic (e.m.) damper could offer these same benefits with lower power consumption and with less mechanical complexity than existing active suspension systems. This research investigates the effectiveness of e.m. passive and active damping on the performance of lightweight electric vehicles and develops a novel, fully integrated model of the e.m. damper in both passive and active modes. The proposed e.m. damper consisted of one or more cylindrical permanent magnets that travelled axially through one or more cylindrical solenoids. A magnet/solenoid damper system was modelled for both the passive and active modes. The magnets were modelled as a current carrying solenoid and from Maxwell's Laws the magnetic field was determined. For the passive damper, the magnetic field was used with Faraday's Law to determine the forces generated. In the case of the active damper the magnetic field and the current in the damper solenoid were used to calculate the magnetic force. Both a passive and active e.m. damper were modelled for a small, one degree of freedom experimental system. The active e.m. damper was modelled as a pure Skyhook damper. There was a good correlation between the modelled and experimental data for the magnet, the passive and the active Skyhook dampers. The passive damper model was scaled up as a two degree of freedom system using realistic values for a road legal lightweight electric vehicle and demonstrated that sufficient passive damping could be achieved for automotive uses, but at the price of excessive mass. For the scaled up active damper model, sufficient force could be achieved with a mass similar to a commercial hydraulic damper. The power consumption was less than 5 % of an equivalent active hydraulic suspension system. This demonstrated that the passive damper was currently impractical for lightweight electric vehicles, but the active electromagnetic damper was of sufficiently low weight and power consumption: had enough authority and offered sufficient passenger comfort benefits to include in future lightweight electric vehicle designs

Advanced spacecraft: What will they look like and why

The next century of spaceflight will witness an expansion in the physical scale of spacecraft, from the extreme of the microspacecraft to the very large megaspacecraft. This will respectively spawn advances in highly integrated and miniaturized components, and also advances in lightweight structures, space fabrication, and exotic control systems. Challenges are also presented by the advent of advanced propulsion systems, many of which require controlling and directing hot plasma, dissipating large amounts of waste heat, and handling very high radiation sources. Vehicle configuration studies for a number of theses types of advanced spacecraft were performed, and some of them are presented along with the rationale for their physical layouts

Civil space technology initiative

The Civil Space Technology Initiative (CSTI) is a major, focused, space technology program of the Office of Aeronautics, Exploration and Technology (OAET) of NASA. The program was initiated to advance technology beyond basic research in order to expand and enhance system and vehicle capabilities for near-term missions. CSTI takes critical technologies to the point at which a user can confidently incorporate the new or expanded capabilities into relatively near-term, high-priority NASA missions. In particular, the CSTI program emphasizes technologies necessary for reliable and efficient access to and operation in Earth orbit as well as for support of scientific missions from Earth orbit

Space Structures: Issues in Dynamics and Control

A selective technical overview is presented on the vibration and control of large space structures, the analysis, design, and construction of which will require major technical contributions from the civil/structural, mechanical, and extended engineering communities. The immediacy of the U.S. space station makes the particular emphasis placed on large space structures and their control appropriate. The space station is but one part of the space program, and includes the lunar base, which the space station is to service. This paper attempts to summarize some of the key technical issues and hence provide a starting point for further involvement. The first half of this paper provides an introduction and overview of large space structures and their dynamics; the latter half discusses structural control, including control‐system design and nonlinearities. A crucial aspect of the large space structures problem is that dynamics and control must be considered simultaneously; the problems cannot be addressed individually and coupled as an afterthought

Electromagnetic damper control strategies for light weight electric vehicles

An investigation is conducted into the performance of passive, semi-active and active electromagnetic dampers. Theoretical models are constructed of the dampers and these are included in two degree of freedom models of the suspension. The passive and semi-active electromagnetic dampers are significantly heavier than commercial hydraulic dampers. In the case of active electromagnetic damper, the reduction in passenger acceleration is 88 percent when compared to passive damper and 61 percent when compared to a semi-active damper. The power consumption is similar to a magnetorheological semi-active damper

Index to 1981 NASA Tech Briefs, volume 6, numbers 1-4

Short announcements of new technology derived from the R&D activities of NASA are presented. These briefs emphasize information considered likely to be transferrable across industrial, regional, or disciplinary lines and are issued to encourage commercial application. This index for 1981 Tech Briefs contains abstracts and four indexes: subject, personal author, originating center, and Tech Brief Number. The following areas are covered: electronic components and circuits, electronic systems, physical sciences, materials, life sciences, mechanics, machinery, fabrication technology, and mathematics and information sciences

An analytical and numerical study of magnetic spring suspension and energy recovery mechanism

As the automotive paradigm shifts towards electric, limited range remains a key challenge. Increasing the battery size adds weight, which yields diminishing returns in range per kilowatt-hour. Therefore, energy recovery systems, such as regenerative braking and photovoltaic cells, are desirable to recharge the onboard batteries in between hub charge cycles. While some reports of regenerative suspension do exist, they all harvest energy in a parasitic manner, and the predicted power output is extremely low, since the majority of the energy is still dissipated to the environment by the suspension. This paper proposes a fundamental suspension redesign using a magnetically-levitated spring mechanism and aims to increase the recoverable energy significantly by directly coupling an electromagnetic transducer as the main damper. Furthermore, the highly nonlinear magnetic restoring force can also potentially enhance rider comfort. Analytical and numerical models have been constructed. Road roughness data from an Australian road were used to numerically simulate a representative environment response. Simulation suggests that 10’s of kW to >100 kW can theoretically be generated by a medium-sized car travelling on a typical paved road (about 2–3 orders of magnitude higher than literature reports on parasitic regenerative suspension schemes), while still maintaining well below the discomfort threshold for passengers (<0.315 m/s 2 on average)

Technology for the Future: In-Space Technology Experiments Program, part 2

The purpose of the Office of Aeronautics and Space Technology (OAST) In-Space Technology Experiments Program In-STEP 1988 Workshop was to identify and prioritize technologies that are critical for future national space programs and require validation in the space environment, and review current NASA (In-Reach) and industry/ university (Out-Reach) experiments. A prioritized list of the critical technology needs was developed for the following eight disciplines: structures; environmental effects; power systems and thermal management; fluid management and propulsion systems; automation and robotics; sensors and information systems; in-space systems; and humans in space. This is part two of two parts and contains the critical technology presentations for the eight theme elements and a summary listing of critical space technology needs for each theme

Comparison of smart panels for tonal and broadband vibration and sound transmission active control

This paper presents a comprehensive overview of the principal features of smart panels equipped with feed-forward and feedback systems for the control of the flexural response and sound transmission due respectively to tonal and to stochastic broadband disturbances. The smart panels are equipped with two types of actuators: first, distributed piezoelectric actuators formed either by small piezoelectric patches or large piezoelectric films bonded on the panels and second, point actuators formed by proof-mass electromagnetic transducers. Also, the panels encompass three types of sensors: first, small capacitive microphone sensors placed in front of the panels; second, distributed piezoelectric sensors formed by large piezoelectric films bonded on the panels and third point sensors formed by miniaturized accelerometers. The proposed systems implement both single-channel and multi-channel feed-forward and feedback control architectures. The study shows that, the vibration and sound radiation control performance of both feed-forward and feedback systems critically depends on the sensor-actuator configurations