MMA actuator and Multi-channel electronics for Electro-hydraulic valve control in shock absorbers

The custom system containing 4 miniature electromagnetic actuators combined with a dedicated four-channel controller, is designed to provide practical solutions for engineers seeking enhanced adaptability in automotive applications. This custom system enables real-time adjustments of shock absorbers from within the vehicle – a feature that can greatly assist in fine-tuning suspension dynamics for various road conditions and driving preferences.

Best achievable performance

Fast hydraulic



Problem and approach

Modern car suspension systems are under increasing pressure to provide both flexibility and comfort. The ability to adapt is usually achieved by changing shock absorber settings or the ride height using electronic controls within the car, like buttons or touch screens. These controls manipulate a valve or restriction in the shock absorber, altering its behavior. This adjustment can be felt as the car reacting softer or firmer when encountering different road surfaces, such as cobblestone. Most cars offer three settings: “Comfort,” “Normal,” or “Sport.”

In the past, custom suspension systems with adjustable shock absorbers relied on manually operated mechanical valves. These valves had to be adjusted under the car’s hood using tools like an allen key. This meant that changes couldn’t be made while driving.

The next generation of aftermarket suspension systems aims to address this limitation by allowing shock absorber adjustments from inside the car. In response to these challenges, our team undertook the task of developing a solution that seamlessly integrates with existing platforms and need to withstand the challenges of automotive conditions.
Technical discussions lead to the strategic decision of harnessing miniaturized MMA (Moving Magnet Actuator) technology for hydraulic valve control. This project required a compact electromagnetic hydraulic valve actuator integrated into the system, along with a four-channel electromagnetic actuator controller (one for each wheel).

The integration of MMA technology within the shock absorber’s hydraulic circuit presented the most compact solution, ensuring optimal shock absorber performance. The main challenge revolved around enabling the MMA to function seamlessly within hydraulic fluids and endure dynamically fluctuating hydraulic pressures depending on varying road conditions.

Project Results

Addressing the electronic control aspect, a specialized 4-channel current controller was developed. This controller featured 2 rotary switches, each offering 10 distinct settings, ensuring individualized control over the front and rear shock absorber configurations.

In-depth laboratory testing validated the stability and reliability of the hydraulic valve controller actuator within the shock absorber unit. External sensors were employed, subjecting the system to elevated temperatures to replicate worst-case scenarios.

Over a span of 2 years, an extensive field test was conducted by integrating the MMA actuator and Multi-channel electronics into a BMW M3 sportscar. The field existed out of approximately 40,000 km of driving across diverse conditions. Notably, the system demonstrated flawless performance throughout this period, without any identified issues.

As a result, the Suspension system product was effectively introduced to the market, highlighting the success of this project.


The actuator has to facilitate a hydraulic sealing surface and an accurate guiding system with a 5 mm stroke. It has to withstand demanding hydraulic oil environment under a maximum pressure of 19 Bar. Furthermore, the actuator was required to maintain accurate position control without relying on external sensing, even in environmental temperatures reaching up to 100 degrees Celsius.

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