Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Motion Control Keeps Electric Car’s Four Wheels—and Four Motors—on the Road

24.01.2013
It weighs half as much as a sports car, and turns on a dime—so its no surprise that the electric car being developed at Ohio State University needs an exceptional traction and motion control system to keep it on the road.

With four wheels that turn independently, each with its own built-in electric motor and set of batteries, the experimental car is the only one of its kind outside of commercial carmakers’ laboratories.


An experimental electric car under development at Ohio State University. Photo by Junmin Wang, Courtesy of Ohio State University.

“It is considered one of the promising future vehicle architectures,” said Junmin Wang, assistant professor of mechanical engineering and Director of the Vehicle Systems and Control Laboratory at Ohio State. “It would make a good in-city car—efficient and maneuverable, with no emissions. Our task is to make a robust control system to keep it safe and reliable.”

In a paper in the January 2013 issue of the journal Control Engineering Practice, his team described the car’s ability to follow a specific trajectory.

In tests on good road conditions at the Transportation Research Center in East Liberty, Ohio, the car followed a driver’s desired path within four inches (10 cm). To test slippery road conditions, the researchers took the car to an empty west campus parking lot on a snowy day. There, the car maneuvered with an accuracy of up to eight inches (20 cm), and the vehicle traction and motion control system prevented “fishtailing” through independent control of the left and right sides of the car.

Wang characterized these results as more accurate than a conventional car, though the comparison is hard to make, given that conventional cars are much more limited in maneuverability by the transmission and differential systems that link the wheels together mechanically. The four independent wheels of the electric car give drivers greater control and more freedom of movement.

The experimental car also weighs half as much as a conventional car—only 800 kg, or a little over 1,750 pounds—because it contains no engine, no transmission, and no differential. The researchers took a commercially available sport utility vehicle chassis and removed all those parts, and added a 7.5 kW electric motor to each wheel and a 15 kW lithium-ion battery pack. A single electrical cable connects the motors to a central computer.

One hundred times a second, the onboard computer samples input data from the steering wheel, gas pedal and brake and calculates how each wheel should respond. Because the wheels are independent, one or more can brake while the others accelerate, providing enhanced traction and motion control.

In fact, a driver who is accustomed to conventional cars would have a difficult time driving a car of this experimental design, known as a “four-wheel independently actuated” (FIWA) car without the help of the vehicle motion and traction control system. With its ability to turn sharply and change direction very quickly, the car could be hard to control. Wang has tried it.

“Without the controller, it’s very hard to drive. With the controller, it’s quite nice—quiet, and better control than commercial four-wheel drive,” he said.

The main challenge for his team—which consists of bachelor’s, master’s, and doctoral students as well as a few local high school students—is to make the whole traction and motion control system energy-efficient and fault-tolerant, so if one wheel, motor or brake malfunctions, the others can compensate for it and maintain safety. It’s a situation analogous to a multi-engine plane losing an engine: the other engines have to adjust thrust and angle to keep the plane safe and on course.

Future work will concern the FIWA car’s energy efficiency for increasing its travel range in urban environments, and optimizing the weight distribution in the car.

Wang estimates that we won’t see a FIWA car on the road for another 5-10 years, as researchers continue to develop new algorithms to control the car more efficiently and add more safety features.

The coauthor on the paper was Rongrong Wang, a doctoral student in mechanical engineering, and the team’s high school participants came from the Columbus Metro School, a state of Ohio public STEM (science, technology, engineering, math) high school open to students from around the state.

This research was supported by Junmin Wang’s awards from the Office of Naval Research Young Investigator Program (2009) and the National Science Foundation’s Faculty Early Career Development Program (2012); the Honda-OSU Partnership program; and the OSU Transportation Research Endowment Program.

Contact: Junmin Wang, (614) 247-7275; Wang.1381@osu.edu
Written by Pam Frost Gorder, (614) 292-9475; Gorder.1@osu.edu
Editor’s note: a photograph of the experimental FIWA car is available from Pam Frost Gorder.

Pam Frost Gorder | EurekAlert!
Further information:
http://www.osu.edu

More articles from Automotive Engineering:

nachricht 3D scans for the automotive industry
16.01.2017 | Julius-Maximilians-Universität Würzburg

nachricht Improvement of the operating range and increasing of the reliability of integrated circuits
09.11.2016 | Technologie Lizenz-Büro (TLB) der Baden-Württembergischen Hochschulen GmbH

All articles from Automotive Engineering >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>