Cruise control has evolved
Question: How about a tutorial on the GM adaptive cruise control system? Specifically, I'm curious as to whether the GM system uses engine or mechanical braking, or combinations thereof, in decelerating vehicles when encountering slower traffic. When decelerating, the brake lights are not activated. Doesn't this pose a hazard to following traffic?
Also, I understand other manufacturers use a laser system rather than millimeter-wave radar. Are other technologies involved? I have a 2008 Cadillac DTS and love it.
— Roland Marquis
Answer: We've come a long way from the first cruise control system found on the '58 Chrysler. Conventional cruise control systems use throttle only to try to balance operator-desired speed versus actual vehicle speed. On downgrades, vehicle speed may overrun the desired set speed.
Adaptive cruise control can have many names and is typically found on luxury vehicles, because of its fairly high cost. It is trickling down and may become standard equipment on all vehicles, given time. Adaptive cruise control, or ACC, uses radar, LIDAR (laser) and cameras to perceive vehicles ahead and their behavior. Should you come upon a slower-moving vehicle with ACC engaged, engine throttle is reduced and, if need be, brakes are applied to maintain your desired following distance. Brake lights are deployed when your deceleration rate reaches a calculated threshold.
ACC employs a complex network of vehicle modules to manage things smoothly. Your Caddy uses a distance-sensing cruise control module, located behind the grille, to ping the roadway ahead and classify objects. A yaw sensor tells the system whether you are driving straight or turning. Brake and accelerator pedal sensors indicate possible override input, and your selection of desired following distance is considered. Participating modules include the engine control module, transmission control module, electronic brake control module, instrument panel module and radio amplifier. The system is smart enough to predict brake temperature and downshift the transmission as needed for engine holdback. Should the radio amplifier not work, ACC will stand down, because audible warnings wouldn't be available.
Radar-based systems are the most popular by a wide margin. In some cases, cameras provide additional object classification, coupled with GPS to determine road and intersection characteristics. These super-smart systems can predict the car ahead with a flashing turn signal will probably turn off at the exit — yikes!
Collision mitigation is a logical spinoff of ACC capabilities and is available on many systems. Even with cruise control disengaged, these systems will detect threats ahead and warn you, disengage throttle and apply brakes as needed to avoid a collision.
Let's hope drivers don't become complacent; no system can be expected to function perfectly every time.
In the future, we'll move from autonomous to cooperative systems, where vehicles will communicate with each other. This will allow tightening of following distances and less reactive stop-and-go maneuvering, speeding traffic along more smoothly.
Brad Bergholdt is an automotive technology instructor at Evergreen Valley College in San Jose, Calif. Email him at email@example.com.
Show commenting policy
TribLive commenting policy
You are solely responsible for your comments and by using TribLive.com you agree to our Terms of Service.
We moderate comments. Our goal is to provide substantive commentary for a general readership. By screening submissions, we provide a space where readers can share intelligent and informed commentary that enhances the quality of our news and information.
While most comments will be posted if they are on-topic and not abusive, moderating decisions are subjective. We will make them as carefully and consistently as we can. Because of the volume of reader comments, we cannot review individual moderation decisions with readers.
We value thoughtful comments representing a range of views that make their point quickly and politely. We make an effort to protect discussions from repeated comments either by the same reader or different readers.
We follow the same standards for taste as the daily newspaper. A few things we won't tolerate: personal attacks, obscenity, vulgarity, profanity (including expletives and letters followed by dashes), commercial promotion, impersonations, incoherence, proselytizing and SHOUTING. Don't include URLs to Web sites.
We do not edit comments. They are either approved or deleted. We reserve the right to edit a comment that is quoted or excerpted in an article. In this case, we may fix spelling and punctuation.
We welcome strong opinions and criticism of our work, but we don't want comments to become bogged down with discussions of our policies and we will moderate accordingly.
We appreciate it when readers and people quoted in articles or blog posts point out errors of fact or emphasis and will investigate all assertions. But these suggestions should be sent via e-mail. To avoid distracting other readers, we won't publish comments that suggest a correction. Instead, corrections will be made in a blog post or in an article.
- United Airlines hack coincided with incursion into government employee data
- Post-Gazette offers voluntary buyouts in bid to avoid layoffs
- U.S. Steel CEO expects rebound
- Muni bond funds stressed
- China rebound, Fed statement fuel rally on Wall Street
- Range Resources cuts workforce 11%
- Fed holds steady on rates
- Voice-assisted technology raises privacy concerns
- Ambridge’s PittMoss takes off with help from TV show, Mt. Lebanon native Cuban
- Consol Energy, Range Resources report 2Q losses, plan deeper cuts
- Gold continues to fall further out of favor with investors