How Magnetic Sensors Are Enabling the Next Generation of Braking Systems
We initiate a complex and highly coordinated process every time we press the brake pedal in our vehicles. That familiar action relies on a sophisticated system that converts motion into control, ensuring safety at every stop. Today’s braking systems must function seamlessly under a variety of conditions, whether halting a high-speed SUV or easing a car into a tight parking space.
Magnetic sensors have emerged as a critical component in making these capabilities possible. Their ability to provide accurate, real-time information about mechanical position, motion, and force enables responsiveness and intelligence within braking architectures. As vehicles become more electrified and software-defined, these sensors are increasingly important.
The Hidden Complexity Behind Every Stop
Modern vehicles must be capable of coming to a stop quickly and safely under enormous loads. For instance, a high-powered SUV accelerating from 0 to 100 kilometers per hour in five seconds can travel over 140 meters in that time. To stop safely in less than a quarter of that distance, the braking system must dissipate nearly a megawatt of kinetic energy while maintaining stability and steerability.
This same system must also perform nuanced actions like holding the vehicle steady on a hill or gradually slowing to a stop in heavy traffic. Braking systems depend on high-performance mechanical hardware supported by smart electronic control to achieve power and precision. Accurate sensor input is essential for determining component positions such as pedal angle, piston movement, and brake pad engagement.
The Shift from Hydraulic to Electronic Braking
For decades, braking systems have relied on hydraulic circuits to transmit force from the pedal, such as the model shown in Figure 1, to the wheels. However, the increasing adoption of electrification is reshaping this architecture. Traditional systems are being augmented, and in some cases replaced, by electromechanical solutions.
Brake pedal assembly with sensor and actuator module. The sensor detects drivers’ intent.
The introduction of electro-hydraulic boosters and electric parking brakes marked the beginning of this shift. These systems reduce complexity by replacing vacuum components and mechanical cables with compact, electronically controlled motors. Hybrid configurations, where the front wheels retain hydraulics for higher braking loads while the rear wheels use electronic actuators, are already on the road today.
In the near future, brake-by-wire systems will become increasingly common. These systems eliminate hydraulic fluid altogether and replace it with electrical signaling and motor-driven actuation. The result is a cleaner, lighter, and more controllable system, especially critical for electric vehicles and autonomous platforms.
How Magnetic Sensors Support Braking Control
The transition from hydraulic to electronic braking depends on reliable sensing. Magnetic sensors operate without physical contact and are particularly well-suited to automotive environments due to their resistance to vibration, temperature extremes, and contamination.
Magnetic sensors are used in multiple ways throughout the braking system. They monitor how far the driver presses the brake pedal, enabling the ECU to understand intent and apply braking force accordingly. They also track the position of pistons and calipers, confirming whether braking mechanisms are fully engaged or retracted in locations such as the one illustrated in Figure 2. In systems where hydraulic fluid is still used, sensors help detect low fluid levels in the reservoir, triggering warnings or adaptive responses. Additional applications include confirming whether the parking brake is set and integrating with wheel speed data to support features like hill-hold assist.
Brake caliper with actuator modulet. The sensor detects brake piston travel, ensuring drivers’ intent is applied.
Specialized Sensor Types for Specialized Roles
Braking systems rely on multiple sensor types, each engineered for specific tasks. Linear sensors track horizontal movement, such as the distance a pedal travels. Rotational sensors detect angular position changes, essential for electric motors controlling brake calipers or boosters. Some applications use 3D or multi-axis sensors to capture compound motion, such as a switch being pressed and rotated simultaneously. Even simple magnetic switches, which detect whether a component is open or closed, remain relevant for end-position detection.
The variety of sensor functions reflects the complexity and precision required in braking applications. No single sensor type can handle every role, so systems are designed with a combination of specialized sensors, each selected for its performance and environmental tolerance.
Addressing EMC Challenges and Ensuring Redundancy
The rise of electrification brings a new challenge: electromagnetic compatibility. With electric motors, inverters, and other high-current components generating magnetic fields throughout the vehicle, sensors must be able to distinguish meaningful signals from background interference. Techniques such as differential signal processing, advanced sensor geometries, and embedded shielding are used to isolate the target magnetic field from environmental noise.
Safety is another critical factor. Braking systems must comply with standards such as ISO 26262, which require systems to function even in the event of a component failure. To meet these requirements, sensor redundancy is essential. Importantly, this redundancy must be heterogeneous, meaning using two different sensing principles or technologies to ensure that a single mode of failure cannot affect both. This design philosophy enhances fault tolerance and supports the overall safety architecture of the vehicle.
Real-World Examples of Sensor Integration
Magnetic sensors can be found at every critical control point in a modern braking system. Near the brake pedal, angle or multi-axis sensors capture the driver’s input with high resolution. This information allows the system to apply braking force proportionally and precisely.
Within motorized actuators, such as those used in electromechanical brake systems, sensors monitor shaft or gear position to confirm accurate application and release of braking force. These sensors provide real-time feedback to the control unit, allowing for quick adjustments and consistent braking behavior.
Multiple sensors may be deployed in parallel to ensure system reliability, often with each sensor using a different measurement principle. For example, a Hall-effect sensor may be paired with a tunnel magnetoresistance (TMR) sensor to create a redundant, fail-safe arrangement.
In high-EMC environments like electric or hybrid vehicles, sensors with differential signal architectures, such as the system shown in Figure 3, can maintain accuracy without heavy shielding. These advanced designs reject common-mode noise, focusing only on changes in the target field.
Detailed view of the actuator module. The sensor controls the turns of the shaft of the electric motor by sensing the poles of the magnet at the end of the shaft, translating into the travel of the piston.
The Road Ahead: Software-Defined Braking Systems
The move toward brake-by-wire mirrors a trend seen in steering systems, which have transitioned from hydraulic to fully electronic control. As braking systems evolve in the same direction, the number of magnetic sensors used per vehicle is expected to grow. In some designs, more than 20 sensors may be deployed, each fulfilling a specific function in the braking control chain.
This increased sensing capability opens the door to enhanced vehicle performance. Braking systems will not only stop the vehicle but also adapt to road conditions, predict wear on components, and integrate more deeply with autonomous driving features. With the right sensor infrastructure, software-defined braking can deliver both safety and adaptability.
Smart Brakes
Magnetic sensors have moved from supporting roles to central pillars in the architecture of modern braking systems. Their ability to deliver precise, resilient, and real-time data is critical to everything from pedal feel and caliper control to system diagnostics and predictive maintenance.
As electrification and automation reshape the automotive landscape, magnetic sensing will continue to underpin safe, intelligent, and responsive braking, ensuring that every stop is as smart as it is secure.
RESOURCES
TDK-Micronas | www.micronas.tdk.com
PUBLISHED IN CIRCUIT CELLAR MAGAZINE • JUNE 2025 #419 – Get a PDF of the issue
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Karsten Köhler works as a Business Development Manager at TDK-Micronas in Freiburg, Germany. He is focusing on application of semiconductors, mainly sensors and drivers, in automotive applications. With more than 20 years of experience in leadership roles in electronics technology development, sales / key account management, and product management, he is blending technological innovation with sustainable business models. Karsten is taking active roles in industry associations, e.g., ZVEI Germany, and standardization gremiums. He is publishing regularly on the role of semiconductors in automotive innovations, such as electrified drivetrains, steer-by-wire, or brake-by-wire.Karsten holds master’s degrees in engineering as well as business administration.
