In this interview, TE Connectivity provides a detailed breakdown of the technology behind these sensors, discussing both passive and active sensing technologies, the challenges they face in harsh operating environments, and how leading solutions like TE's high-resolution wheel speed sensors are designed to overcome these obstacles.
What is a wheel speed sensor, and what is its critical role in automotive systems?
When you look at a wheel speed sensor, it essentially measures the rotational speed of the wheel. It is a crucial component that provides wheel speed information to active safety systems, such as the ABS module, electronic stability control, and traction control systems. This is its primary purpose in automotive vehicle safety.
What different technologies are used for wheel speed sensors?
There are two types of wheel speed sensors: a passive sensor that uses magnetic inductive technology and an active sensor that utilizes Hall effect and magneto-resistive technology.
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What common challenges are associated with wheel speed sensors?
The nature of these sensors, which are crucial for supporting automotive safety functions, means they must adhere to strict automotive standards.
Because they are located at the wheel hub or brake assembly, they must endure tough operating conditions, such as high temperatures, high humidity, electromagnetic interference, noise, undesirable vibrations, chemical exposure, dust, and pollution. These are the common challenges associated with wheel speed sensors.
What are some methods to overcome these challenges, and how can TE contribute to this?
TE has over 20 years of experience in manufacturing mill ST sensors. We understand that these sensors are mounted in the wheel hub, where they are exposed to harsh conditions.
To address these challenges, we use robust technologies with integrated signal processing, protective casings, and durable installation methods. Our sensors are fully validated using reliability engineering methodologies to ensure they can withstand up to 15 years of operation.
What advantages does a high-resolution wheel speed sensor (HR WSS) provide over other technology types?
TE's high-resolution wheel speed sensor offers a significant advantage over standard wheel speed sensors by providing more precise measurements of vehicle movements.
A standard wheel speed sensor, also known as an ABS sensor, detects the rotational speed of a magnetic encoder with a set of magnetic pole pairs, typically generating two pulses per pole pair. These pulses are sent to the vehicle’s ECU to determine wheel position.
In contrast, the high-resolution wheel speed sensor can generate up to four times more pulses than a standard sensor, offering higher resolution and precision. This increased data output leads to significant improvements in vehicle motion control, enhanced vehicle dynamics, and better overall customer comfort and safety.
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What else does an HR WSS provide that helps enhance vehicle safety, and what next-generation functions does it enable?
The high-resolution wheel speed sensor provides more precise vehicle positioning and control, offering faster and more accurate response times. It reduces uncertainty margins for direction detection and delivers robust performance under various conditions.
When it comes to next-generation functions, the high-resolution wheel speed sensor significantly enhances advanced driver assistance systems (ADAS) and automated driving systems (ADS) by providing more precise and reliable data.
This supports functions such as accurate antilock braking systems, enhanced traction control and stability, improved adaptive cruise control, highly automated parking applications, hill assist, automated emergency braking. These are the next-generation functions that high-resolution wheel speed sensors enable.
What validation and testing, such as the different sensor testing protocols and sensors, are needed to ensure a sensor's reliability and accuracy?
There are two main areas to focus on when validating a new sensor technology.
First, the sensing capability and signal conditioning must meet the customer's needs. In this case, we have validated the sensor's performance across multiple installations and use conditions to ensure that the signal reaching the ECU is robust and consistent from sensor to sensor.
The second area is the durability of the product. With over 20 years of experience, TE employs reliability engineering methodologies to test all our sensors. One of the key testing methods is highly accelerated life testing (HALT), which subjects the sensor to extreme conditions over extended periods. This ensures that the sensor can endure the expected lifespan of 15 years.
What are the key considerations engineers should consider when deciding on a wheel speed sensor?
When selecting a wheel speed sensor, it is important to consider the desired level of resolution and accuracy, as well as whether the sensor’s features can meet the target acceleration requirements. Compatibility with the mechanical systems and ease of integration with ECUs through protocol compatibility are also important factors.
Most importantly, since wheel speed sensors are fundamentally related to safety and associated with the braking system, the most critical factors are the sensor’s design robustness, reliability, and quality.
What are your predictions for the evolution of sensor technology and its implications for the automotive industry?
One of the future goals of OEMs is the full integration of chassis systems to improve driving performance and safety. This will require the steering, braking, and suspension systems to work together seamlessly. However, this fusion presents several challenges that the industry is currently addressing.
As these systems rely more on sensor technologies and as more data becomes available from various sensors and cameras, the computing power in vehicles must be significantly increased.
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This additional computing power must enable fast decision-making, executing countermeasures, and verifying that the countermeasures were executed correctly. Sensors will need to be designed and developed to meet these advanced needs of the automotive industry.
Enhancing existing functionality is just the first step. The automotive and commercial vehicle industries are continuously adapting and upgrading sensor capabilities. Whether automated or autonomous functions occur in controlled environments, such as normal highway driving, or emergencies, such as evasive maneuvers, more data is needed to ensure that the vehicle is responding appropriately.
This is where new sensor technology, such as the high-resolution wheel speed sensor, plays a crucial role in meeting the advanced needs of the automotive industry.
What future developments do you foresee in the field of wheel speed sensors?
Faster data rates and more accurate vehicle positioning are highly valuable for system control, and the high-resolution wheel speed sensor available today is just the first step in meeting these needs. As system requirements evolve, so will the capabilities of wheel speed sensors to keep pace.
At TE, we continuously seek input from OEMs regarding their vehicle architecture, future product generations, and functional safety requirements for advanced automated functions.
This collaboration allows us to develop fully integrated and reliable sensor and connector solutions that align with next-generation system needs. We are actively working with OEMs to ensure that our next-generation wheel speed sensors support and enhance their future developments.
This information has been sourced, reviewed and adapted from materials provided by TE Connectivity Ltd.
For more information on this source, please visit TE Connectivity Ltd.
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