An important next step toward the self-driving car was taken at the 2016 North American International Auto Show with the introduction of the all-new 2017 Volvo S90—a production car with a semi-autonomous driving system as standard equipment.
Built on Volvo's scalable product architecture (SPA), it combines the latest version of the company's Pilot Assist with the XC90's low-speed driver assistance with auto braking system. Capable of operating at up to 80 mph (130 kph), the new system is claimed to detect large animals such as deer and horses and has full day-or-night functionality. It can provide steering inputs to keep the car in lane, and unlike the XC90, can hold the course and lane even without a vehicle ahead to track.
The S90's software goes well beyond that of the XC90, which operates only up to 30 mph ( 50kph), but the key hardware pieces are carried over. They are multiple radar and camera arrays, including an optional 360º camera system for driving and parking in tight quarters, and auto parking.
However, the Pilot Assist operation is based on a forward-looking laser radar from Mahle/Delphi and the newest Mobileye camera. Both have a 140º angle of view, explained Thomas Mueller, Vice President of Electrical and Electronics Systems at Volvo R&D.
Evolution of image detection
Image detection is key, of course, and Volvo introduced pedestrian identification in 2010, followed by operation in darkness in 2012. Volvo's new software, developed with Mobileye but validated by Volvo in road testing, with threshold values set by Volvo, has evolved over the last several years.
The "night vision" learned in 2010 was followed by nighttime pedestrian detection, then by identification of bicyclists. And there is work ongoing beyond even the large animal detection, to identify sudden appearance of fixed objects in the road that could pose a hazard, such as a stack of bricks or a sofa, Mueller said.
The software uses the inputs of the standard array of sensors and cameras, plus a premium-accuracy GPS, to create a high definition 3D digital map of the area surrounding the car, with some measurements claimed by Volvo to be accurate to the millimeter level.
In addition, Volvo employs a new, continuous road traction identification algorithm for the S90. This enables the control system to adjust for the road surface itself, plus the performance of the brakes and tires, Mueller said.
Because the hardware is carried over from the XC90, the S90 Pilot Assist is backwards-compatible to that model, and Volvo soon will make a reflash available and upgrade the production system on that vehicle. There are tweaks that are necessary for the XC90, Muller noted, specifically pointing to the difference in windshield rake affecting the heads-up-display.
Volvo's confidence in the high-speed system was reflected in this statement, "We will take responsibility for any accidents in autonomous mode."
Leaf spring rear suspension
The SPA has a fixed front wheel center-to-firewall dimension and from that point the chassis can be set to a desired width and length. The S90 is very close in size to the XC90, with a wheelbase of 115.8-in (2941 mm), an overall length of 195.7-in (4963 mm). Curb weight is 1800-2150 kg (3968-4740-lb), with the weight increasing in part according to powertrain. \
Volvo's U.S. powertrain lineup is gasoline-only, and with a 2.0-L four. The S90's base engine is turbocharged and rated at 240 hp (179 kW). A twin-charged (turbo and supercharger) version is rated at 320 hp (239 kW). A high-performance plug-in hybrid, with a range of about 30 mi (50 km) is rated at 400 hp (298 kW). All use an Aisin-sourced AWF8F35 8-speed automatic transaxle.
Like the XC90, the new S90 sedan has a rear leaf spring suspension. While this may sound very SUV-like, it's a convex fiberglass spring mounted transversely, similar to the configuration long used on the Chevrolet Corvette. Front suspension is double wishbone with coil springs. Volvo does offer an optional four-corner air suspension for both models, and the one for the S90 is tuned specifically, so it's likely to provide a smoother ride.
The S90 will be marketed opposite such European sport sedans as the BMW 5-Series. It features "Thor's Hammer" T-shaped headlights and a concave grille reminiscent of the Volvo P1800 sports coupe produced in 1961-73.
Author:Paul Weissler
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