TDK advances automotive sensor design

By Gina Roos, editor-in-chief

TDK Corp., through its InvenSense subsidiary, rolled out a new line of automotive high-accuracy MEMS motion sensors at CES 2019. These include the “MotionTracking” automotive-qualified IAM-20680 and IAM-20680HP six-axis inertial measurement units (IMUs), which expand TDK’s existing line of automotive sensors that include the IAM-20380 gyroscope and IAM-20381 three-axis accelerometer. The automotive MEMS sensors can help improve the absolute position of a vehicle in GNSS- and GPS-poor environments, such as tunnels, parking garages, and urban canyons.

Here’s the automotive sensor lineup:

• Touted as the smallest six-axis automotive-qualified sensor (combining a three-axis gyroscope and a three-axis accelerometer), the IAM-20680 is claimed as the industry’s only device featuring 16-bit accelerometers and 16-bit gyroscopes in a series production car today. The operating temperature range is –40°C to 85°C.
• If you’re looking for a beefier and higher-temperature-range IMU, the IAM-20680HP, a high-performance version of the IAM-20680, offers an extended operating temperature range of –40°C to 105°C and high gyroscope and offset thermal stability. It is pin-, package-, and register-compatible with the IAM-20680.
• The IAM-20380, with an operating temperature range of –40°C to 85°C, is claimed as the only automotive-qualified gyroscope fully compatible (pin, package, register, and software) with a three-axis automotive accelerometer (IAM-20381) and an automotive-qualified six-axis device (IAM-20680).
• Similarly, the IAM-20381, with an operating temperature range of –40°C to 85°C, is touted as the only automotive-qualified three-axis accelerometer fully compatible (pin, package, register, and software) with a three-axis automotive gyroscope (IAM-20380) and an automotive-qualified six-axis device (IAM-20680).

Key specs include:

• Gyroscope full-scale: ±250°/s, ±500°/s, ±1,000°/s, ±2,000°/s
• Accelerometer full-scale: ±2g, ±4g, ±8g, ±16g
• Embedded temperature sensor
• 16-bit output for accelerometer, gyroscope, and temperature sensor
• SPI and I²C serial interface
• 512-bit FIFO
• 16-pin LGA package (3 × 3 × 0.75 mm)

Specifically, the six-axis IAM-20680HP or the IAM-20680 can be used to improve the estimate of the position, direction, and speed of a vehicle when the satellite signal is poor or non-existent as well as improve the quality of the position estimation when the satellite signal is strong, said TDK. Other key features include excellent temperature stability that enables navigational driving through challenging environments and low sensitivity error that keeps the car turning correctly. The sensors measure up to 16g acceleration and up to 2,000 degrees per second.

Primary applications for the new sensors include navigation system aids for dead reckoning, automotive lift gate motion detection, accurate location for vehicle-to-vehicle and infrastructure, 360° view camera stabilization, car alarms, telematics, and insurance vehicle tracking.

In addition, the IAM-20680 and IAM-20680HP are designed into the new InvenSense Coursa Drive software solution, claimed as the first inertial-aided positioning software for autonomous vehicle (AV) platform developers. The Coursa Drive is a high-performance extension of the InvenSense Positioning Library (IPL) and improves inertial-only vehicle positioning to

TDK said that the Coursa Drive “delivers a cost-effective, vehicle-dead-reckoning accuracy software solution equivalent to high-end systems costing tens of thousands of dollars.” Primary applications include Level 2 to Level 5 advanced driver-assistance systems (ADAS), robotaxis, trucking, and precision agriculture.

How it works: The inertial navigation system calibrates using the absolute position inputs from high-accuracy GNSS receivers or perception-based systems such as cameras, radar, or LiDAR with high-definition (HD) maps. In real time, the software provides high-rate, 100-Hz delta positions and orientation to the AV systems. In offline mode, it improves accuracy for HD map building and maintenance applications.

Coursa Drive is available to select early partners and customers. Contact the company for more information.

TDK and its group companies will showcase the automotive sensor solutions, along with other sensor products, at CES 2019, in Booth #30306, Las Vegas Convention Center, South Hall 3.