Gear shifting in modern automobiles: from intuition to algorithms
Every automobile has to change gears, be it with a manual, automatic or dual clutch transmission. But which criteria drive our individual shift decisions, and how can we optimize the process technically? At the 16th CTI Symposium Berlin, that’s exactly what one lecture series will be looking into.
Saving fuel comfortably and dynamically
Driving in a way that saves fuel (and hence emissions) is always important, and most people learn about foresight and timely upshifts at driving school. Modern transmissions offer a whole suite of helpful high-tech opportunities that adapt to specific driving scenarios. We should also remember that shift quality is an important part of the driving experience. Comfort is one criterion, but the wish for a dynamic or even sporty response is another, and calls for perfect handling and fast shifts.
Complex, autonomous and connected
Surprising though it may seem, most gear changes are still dictated by the intuition and temperament of the person behind the wheel. However, the driver’s authority is now on the wane because in hybrid automobiles, the electronic drive management system controls the transmission completely. This is the only way to direct the sophisticated choreography of ICE and e-motor, recuperation and boosting.
The system also requires full control over shifting at higher levels of vehicle automation (and ultimately in autonomous automobiles). Driver interference would actually pose a safety risk, just as it would in tomorrow’s connected driving, where information from the cloud or close-range communication is processed in real time.
Super smooth or spongy – a new method evaluates manual shift transmissions objectively
Shift quality is an important point in every automobile review, yet in the case of manual shifts that quality is usually subjective. Some drivers prefer less travel on the gearstick and clutch pedal, others more. And one person’s ‘super smooth’ is another person’s ‘spongy’.
Now a cooperation scheme by the Institute of Automotive Engineering at Technische Universität Braunschweig and AVL List GmbH has developed a procedure to assess manual shift quality objectively, using an adaptive measuring system that tracks the load and travel paths of the gearstick and clutch pedal. The system is simple and efficient, and identifies potential weak spots in a targeted way.
Recuperation when shifting – interesting insights on regenerative braking with various hybrid architectures
Regenerative braking is a defining characteristic of hybrid automobiles; the aim is to use it as intensively as possible. One particular challenge occurs when you need to change gear while braking, which if the recuperating e-motor is linked to the wheels via a transmission (not directly) means always.
A survey by Ford USA has examined this issue in depth in parallel, serial and powersplit hybrid architectures, and presents a new shift category called ‘regen shifting’. Regenerative shifting works both with and without torque interruption (powershift). The lecture will explain the use of regen shifting as a DHT or add-on solution in today’s and tomorrow’s hybrid automobiles, and will discuss the respective efficiency levels in detail.
Ahead of the information curve: with V2X Communication, your all-wheel drive is ready before you need it
Thanks to modern communication technology, automobiles can access a wealth of topical data from various sources. And while the use of the Internet is almost a given, close range communication holds the promise of new and fascinating innovations. The developers at McLaren Engineering set themselves a clear challenge: How can we use ‘Vehicle to Everything’ (V2X) technology to further increase the safety and performance of disengageable all-wheel drives?
The solution: new control algorithms that put your vehicle’s all-wheel drive on standby, then activate it instantly on demand. The system has proven itself not just in simulations, but also in the wintry driving conditions of February 2017 aboard various test vehicles.
Fine tuning for faster shifts – even with an integrated PMSM on a 7-speed DCT
When the hybrid you’re driving in all-electric mode uses a highly inert Permanent Magnet Synchronous Motor (PMSM) in a 7-speed DCT, longer shift times are an issue. Now a research project by CEVT AB (Sweden) has succeeded in reducing those shift times significantly.
The team used various parameters to examine the performance of the active steering the PMSM uses for synchronization during shifting, then developed new and better algorithms. The insights from the computer simulation improve real-life driveability, and can be transferred to clutchless multiple speed transmissions in electric automobiles in general.
Right-foot commands – an innovative algorithm for optimal shift decisions
When we shift gears, our right foot is basically the command centre. A new algorithm developed by AVL List GmbH evaluates the signals it sends in a totally new way. The system registers how much acceleration or thrust is being called up, then makes shift decisions accordingly on a case-to-case basis.
The new gear selection algorithm needs no shift performance maps, and simplifies calibration. It is also suitable for use in connected vehicles, and even autonomous automobiles with no driver to give the commands. The system is adaptive and matches its shift strategy to the driver’s style – or in the case of autonomous vehicles, to a preset driving mode. It detects the most appropriate shift characteristics for each scenario, and improves handling.
Welcome to Berlin!
A market for ideas, a meeting place for experts, a platform for networkers, a forum for discussion, a launch pad for new arrivals, a campus for researchers and inventors, a VIP lounge for decision-makers, an arena for debate, a trading floor for talent … the 16th CTI Symposium in Berlin is all this and more. Why not browse the full programme for all four Symposium Days, then choose your own favourite reasons to attend 2017’s final industry highlight?
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Find all information about the lectures at the 16th CTI Symposium in Berlin in our program: