Electronics and Semiconductors

First high-resolution GMR wheel speed and distance sensor for ADAS applications

18 January 2022

The new A19360 wheel speed and distance sensor from Allegro MicroSystems Inc. is engineered for use in emerging applications in advanced driver assistance systems (ADAS). The giant magnetoresistance (GMR) sensor provides automakers with the signal resolution and reliability required for advanced levels of automation in passenger vehicles and mobility-as-a-service applications.

According to a recent report by consulting firm Strategy&, the first passenger vehicles with level 3 (conditional automation) capabilities should be generally available by the end of 2022, and level 4 (high automation) capabilities available in people-mover applications by 2025. By 2030, vehicles incorporating levels 3, 4 and 5 (full automation) capabilities are expected to make up 20% of the total market in Europe, 12% in the U.S., and 11% in China. While progress has been delayed by COVID-19 and regulatory hurdles, automakers are actively developing software and hardware systems and need components — such as the A19360 — that can enable those systems.

"Our new A19360 sensor is a game changer for automakers working on autonomous vehicles,” said Peter Wells, business line director for speed and sensor interfaces at Allegro. “It’s designed for SAE J3016™ Levels of Driving Automation™ 3, 4 and 5, and helps to safely enable features such as park assist, fully autonomous valet parking and traffic jam assistance with 4x better positional measurement where the tires hit the road. It can even improve autopilot functionality and low-speed control in dense environments.”

Source: Allegro MicroSystems Inc.Source: Allegro MicroSystems Inc.

Automated and autonomous vehicles require superior wheel rotation information for accurate low-speed control. The A19360 provides high-resolution information to automotive systems by generating extra output events per magnetic cycle with a special protocol that’s compatible with electronic control units (ECUs). It includes an eight-event-per-magnetic-cycle mode targeted at ADAS applications, providing an increment for every ~5 mm of tire roll. It also includes a four-event-per-magnetic-cycle mode that doubles the number of outputs per magnetic cycle (compared to a normal wheel speed sensor). This allows designers to halve the number of poles on in-wheel ring magnets to save costs, or increase the air gap and still obtain the same number of increments per revolution.

The A19360 was developed for ISO 26262 ASIL B(D), and is built on Allegro’s monolithic GMR technology with ultra-low jitter and large air gap capabilities. The company’s SolidSpeed Digital Architecture provides the widest dynamic range of operating air gap and highly adaptive performance that eliminates flatlining due to thermal drift and system dynamics.

The A19360 is available in a 2-pin SIP package (suffix UB) that is lead-free, with tin lead frame plating. The UB package includes an IC and protection capacitor integrated into a single overmolded package, with an additional molded lead-stabilizing bar for robust shipping and ease of assembly.

To contact the author of this article, email engineering360editors@globalspec.com


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