Brake-by-Wire: the History of the Future

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Source LSP post


UNTERFOEHRING, Germany – The Brake-by-Wire brake system was designed back in 2005 for e-vehicles and was the first with autonomous driving functionality

The pioneering work of LSP that began in 2005 created a worldwide sensation. It culminated with the presentation of a vehicle in Sweden in 2010 that demonstrated the feasibility of a physical operating principle that almost nobody had previously thought possible. LSP showed it to a number of notable car manufacturers including Volkswagen as well as to leading automotive industry suppliers e.g. Bosch and Continental.

IBS1 represented the world premiere of a brake-by-wire system that combined the functions of brake actuation, brake boosting and ABS/ESC (anti-lock braking/electronic stability control), including initial autonomous driving functions (AEB – Automatic Emergency Braking) as well as featuring recuperative braking with generators – all in one single compact unit.

Related post:
LSP Updates Its Brake-by-Wire Systems

Both, the compact design of the brake system and the precision of the brake pressure control by an electro-hydraulic system was revolutionary – and unimaginable at the time. This was made possible by generating brake pressure through a piston-cylinder system driven by a brushless electric motor and distributing it to several wheel brakes via solenoid valves.

A pedal feel simulator made it possible to completely decouple the driver from the system pressure of the brakes, which then laid the foundation for the first autonomous driving functions such as automatic AEB. On top of that, fully variable pedal characteristics could be achieved. System pressure could now be modified independently of pedal actuation, and regulated or controlled with the utmost precision, all taking into account the braking effect of a generator or of the recuperative electric motor of an electric vehicle.

At the core of this precision pressure control was both a highly accurate position and speed regulation of the piston using a three-phase brushless electric motor as well as a very precise modeling of the relationship between braking torque, brake pressure and electric motor torque.

The signals of the current of the electric motor, the piston position and the pressure in the piston-cylinder unit were essential components in the modeling process.

Brake pressure control was thus possible for the first time through current control of the electric motor, which is a core component of today’s redundancy functions.

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The ABS function and the noise level on snow, ice and µ-split were even improved, which in turn defined a new benchmark for brake control in critical driving situations.

The entire post, with explicit images, can be viewed by clicking HERE.

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