Technological improvements in automotive construction, and the demand for safer and more-fuel-efficient cars, are bringing radical changes to the design of next-generation automobiles.
Replacing mechanical systems within a car with electric systems is not a new concept in automotive design, as evidenced by power windows, electric seat adjustment and push-button ignition. A host of drive-by-wire systems currently in development are extending that to primary, operational automotive functions, employing circuitry to replace heavy, cumbersome mechanical and hydraulic systems. In particular, steer-by-wire has proven attractive for its design benefits and for its potential to enable Automated Emergency Steering (AES). This is where Paragraf’s sensors can help.
What is steer-by-wire?
Steer-by-wire is a steering system that replaces the mechanical linkages of conventional steering with electric circuitry. Sensors mounted in the steering column detect the rotation of the steering yoke/wheel and send the relevant signals to steering motors mounted near the wheels. Amplifiers within the circuit are programmed to control the signal to the motors for better manoeuvrability and control. For instance, the wheels can turn more with less yoke/wheel rotation to aid in manoeuvrability in parking lots – eliminating hand-over-hand steering – while also allowing for tighter control at high speeds.
However, steer-by-wire must also replicate the behaviour of the mechanical steering system in the reverse. When the wheels encounter a bump, pothole or kerb, the system must provide feedback to the driver on road conditions and wheel position. To enable this, an additional set of sensors must be placed at the steering wheel that can send signals back to the yoke/wheel to indicate changes in the front wheel’s position.
Importantly, using an electronic/software solution allows for developments in automatic steering not possible with mechanical linkages. The steer-by-wire system enables other inputs, such as line detection or proximity sensing, to be used to help determine whether a change in steering is required for safety purposes – leading the way for AES.
How do Paragraf sensors help enable steer-by-wire solutions?
Paragraf’s graphene Hall effect sensors (GHS) offer high-performance operation for steer-by-wire applications. Our sensors boast the superior resolution necessary to provide the precise measurements that steer-by-wire requires. That resolution also provides flexibility in positioning of the sensor, allowing design engineers greater freedom in construction. Further, our sensors do not respond to stress and strain to the degree that conventional semiconductor devices are prone, meaning that they are far less likely to require complex recalibration.
With their low form factor and power requirement, the sensors can ensure safe steering by being employed in large enough numbers that their circuitry is redundant, an important safety consideration for NCAP programs responsible for regulating the global automotive market.
The active element in Paragraf’s sensors comprises a true, contamination-free, one-atom-thick sheet of graphene produced by Paragraf’s proprietary graphene deposition technique. This produces sensors with high resolution and reliable position sensing beyond existing magnetic sensor solutions, for the immediate detection of small adjustments in the position of the yoke/wheel and steering knuckle.
The under-the-hood automotive environment – particularly in EVs – generates significant electrical and therefore magnetic noise. The two-dimensional nature of our graphene element renders our sensor immune to magnetic fields in the plane of the sensor (planar Hall effect), greatly reducing the readings from stray fields.
The fundamental thermal and mechanical properties of graphene make the sensors more robust, with no loss of linearity across an extreme range of temperatures, and free of hysteresis so the resolution remains consistently reliable.
Paragraf is aware of the challenges that the industry faces on the road to widespread adoption of AES. Please contact us to discuss how we can be a key partner in steer-by-wire technology.