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From Mechanically-Based To Software Defined – How ADAS Systems Have Evolved

The American Society of Automotive Engineers (SAE) defines six levels of driving autonomy.

Dan-ClementFar from the simpler designs of a decade or so ago, modern vehicles are now bristling with features and functionality. While some offer enhanced safety, others improve comfort, or simply differentiate an automaker’s offering to increase sales.

At the ‘comfort’ end, we now often find ambient lighting, high-end entertainment systems, multiple performance modes, memory seats, mirror adjustments and other similar features. In terms of safety, which includes Advanced Driver Assistance Systems (ADAS) we find adaptive cruise control (ACC), automatic emergency braking (AEB), backup cameras, forward sensing, surround-view cameras, all of which are intended to help the driver avoid mistakes – and accidents.

A century ago, ADAS systems were limited to things like mechanical cruise control while now we are considering the vision of software-defined vehicles, based around augmented and virtual reality (becoming known as the metaverse), with the capability for fully autonomous driving.

The American Society of Automotive Engineers (SAE) defines six levels of driving autonomy, with ‘0’ meaning none at all and ‘5’ meaning full autonomy in all conditions, in all locations. Currently, many / most vehicles are at level ‘2+’ where partial automation is allowed, but the driver may be required to take over at any moment should a situation be beyond the vehicle’s capability. The industry remains committed to achieving level 5, but there are a significant number of challenges to be overcome.

Early systems

Many agree that the first driver assistance was a system called ‘Speedostat’ – a speed control system (Steinken, 2020), designed by engineer Ralph Teetor. Blinded when just a child, Teetor used his sight impairment to develop an elevated sense of touch and the ability to hyperfocus. It was claimed that these talents were why he succeeded in engineering as an inventor. His life was documented in the Smithsonian Magazine (Sears, 2018).

The Speedostat, or “Stat” as it became known, was patented in 1950. It used a dashboard speed selector connected to a mechanical governor mechanism, driven by the driveshaft. This governor, in turn, drove a vacuum pump that pushed up on the gas pedal, thereby indicating to the driver to slow down.

The ‘Stat’ was featured in the respected publication, Popular Mechanics in 1950 (Sears, 2018), describing it as “a kind of power-operated accelerator or governor with extras. It takes us several miles farther down the road to automatic pilots for cars.”

The first automaker to adopt the Speedostat was Chrysler – it became their “Auto-Pilot” in 1958. Cadillac coined the term “Cruise Control” which became ubiquitous, remaining in use even now (Teetor, 2020).

Ralph Teetor with his ‘Speedostat’
Figure 1: Ralph Teetor with his ‘Speedostat’ in 1957. Image courtesy of the Automotive Hall of Fame

Around the same time, the invention of the silicon transistor gave rise to a brand new technology – the integrated circuit (IC). The industry moved rapidly from discrete transistors to having the ability to create entire circuits on an IC. Based upon this, Daniel Wisner invented and subsequently patented (in 1971) the first electronic cruise control, known as the “Speed Control for Motor Vehicles” (Niemeier, 2016).

A large step forward at the time, Wisner’s invention could control the vehicle’s speed using a closed feedback loop, even on inclines and declines. This invention, which was an industry-first, eventually became known as cruise control and it changed motoring significantly.

Motorola’s MC14460
Figure 2. Motorola’s MC14460 was the first cruise control chip. Image courtesy

It was widely adopted and, due to its popularity, Motorola invested in the design and fabrication of a silicon chip based upon his algorithm during the late 1980s. Known as the MC14460, this chip was used in many vehicles for many years. Even though the chip was retired some time ago, the embedded Wisner algorithm is still in common
usage today.

GM all-electronic cruise control
Figure 3. 1996 GM all-electronic cruise control compared with an earlier vacuum-based system. Image courtesy of LS Engine DIY

While early cruise control was able to regulate vehicle speed, it was only really useful in light traffic conditions. The next step forward, in the early 1990s, was ACC – invented by William Chundrlik and Pamela Labuhn (Steinken, 2020). Based upon normal cruise control, with similar operation, ACC also included a range-finding sensor to detect and reduce speed when behind slower vehicles, while still maintaining speed control. The detector in early systems was laserbased, but radar, LiDAR and cameras have also been used in the huge
variety of systems available.

Intelligent braking systems

Anti-lock braking systems (ABS) began within the aviation industry (Unknown, Wikipedia, 2021) when, in 1920, aircraft and automobile pioneer, Gabriel Voisin, designed a mechanical ABS system for airplanes based upon a flywheel that spins with the aircraft wheel, controllingthe hydraulic valve of the brake system. If the wheel and the flywheel were spinning together, the system operated the valve to release the brakes. If there was a speed difference, this indicated that the wheel was skidding, so the system opened the hydraulic brake valve, allowing
the tire to spin again.

While simple, this early ABS reduced braking distances as much as 30%, making flights possible in conditions that would have previously grounded aircraft – it also significantly reduced tire wear.

Elsewhere, fully mechanical ABS was trialed on the Royal Enfield Super Meteor motorcycle in 1958. While the system demonstrated that ABS significantly reduced skids – a common cause of accidents – the system was dropped as technical management could not see value in the idea.

During the 1960s, a further system was trialed in cars such as the Ferguson P99, Jensen FF, and the all-wheel-drive Ford Zodiac. This system never caught on, mainly as it was expensive and not reliable.

It was not until the 1960s that fully electronic ABS was deployed – on the flagship British/French supersonic airplane known as Concorde. Due to its design, Concorde required a longer than normal runway for take-offs and landings. ABS was necessary for day-to-day operation, eliminating the possibility of skidding off the runway. Concorde required a speed of 250 knots for take-off, significantly more than typical commercial aircraft both then and now (Unknown, Heritage Concorde, 2021), so ABS was essential for any aborted take-offs on wet or slippery runways.

Bendix Corporation patented the use of electronic ABS on consumer vehicles in 1970 and Chrysler implemented the system on their Chrysler Imperial a year later. Branded by Chrysler as “Sure Brake” it soon became known as “anti-skid” (Schafer, 1971). The system was reliable and soon spread throughout the automotive industry, with
automakers releasing their own variants.

Despite Bendix’s patent, Mario Palazzetti in the Fiat Research Center is generally credited with the invention of ABS, mainly for his work improving the system. In fact, many referred to Palazetti as ‘Mister ABS’. His system was bought by Bosch Mobility Solutions and renamed “ABS”, continuing for many years until it became a standard feature (Unknown, Did You Know Cars, n.d.). It is now a standard feature on almost every vehicle.

Mercedes-Benz testing ABS
Figure 4. Mercedes-Benz testing ABS in the 1970s. Image courtesy of stuff

Traction Control

Wheels can also slip if too much power (for the conditions) is applied so traction control systems (TCS) were developed to control the power sent to the driven wheels. Before electronic systems were available, a limited-slip differential mechanically limited power to the slipping wheel on vehicles where it was fitted. By the early 1970s, electronic TCS was being added to vehicles. These systems monitor wheel speed – specifically looking for differences between wheel speeds – to control the amount of power delivered to each wheel. Some systems achieved this using the vehicle’s throttle, but use of the braking system became the preferred solution. As a result, most TCS are combined with the ABS described earlier. In common with ABS, TCS is a standard feature

Stability Control

A further advancement – stability control – emerged on vehicles during the early 1990s and the 1995 Mercedes-Benz S600 coupe was equipped with a Bosch system (Markus, 2020). Generally, stability control is also integrated with the ABS and TCS, implementing more sensors to see how the vehicle responds to throttle and steering inputs from the driver. The additional sensors include a steering wheel sensor, a yaw sensor and accelerometers and data from these is combined to determine how the vehicle is currently driving. From this analysis, the stability control system can adjust braking, throttle, or suspension to improve handling.


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BiS Team

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