Are we there yet?

Are we there yet?

Safety has attracted the majority of investment in the development of connected and autonomous vehicles (CAVs), but there is also a widespread public expectation of comfort levels approaching those of a living room environment while in motion.  Ricardo engineers are working on a solution for motion sickness in CAVs which can be applied in conventionally-driven vehicles as well

Kinetosis, or motion sickness, is not a new problem. But as new use-case scenarios for  vehicles emerge, avoiding motion disturbance – as a minimum – and guarding against passenger nausea are becoming greater concerns. Autonomous driving and driverless vehicles bring particular issues, since people expect to be able to work, to read from a screen, watch a movie or hold a conversation in motion, perhaps while sitting in a swivelled,
side- or rear-facing position. All these are factors known to contribute to kinetosis. Solving car sickness will therefore be crucial for consumer acceptance of CAVs.

Having a young daughter very prone to car sickness personally motivated Professor Jonathan Wheals, chief engineer, Ricardo Innovations, to research this topic. He recognized a general lack of knowledge around the effects of automotive motion on children and teenagers, as well as on rear-seat occupants. And, given the industry’s concentration on safety, he believed that kinetosis has been neglected in CAV-related R&D thus far.

“About a year and a half ago, we started thinking about this in detail,” he says. “Autonomous vehicles will be safe, or they will not be sold; the question now is what new activities are enabled by these vehicles? New is the ability to read, use a tablet and everything else while travelling. But if you no longer have a driver who has sympathy with the occupants, and
an algorithm controlling the vehicle, it doesn’t know who’s in the car, or what their particular sensitivities are.”

Wheals also contends that the application of these same techniques to non-CAVs would be beneficial to customers. Cars, he explains, tend to be engineered for 40-60-year-old males, of a certain weight and build, who have a certain response to things, sitting as a driver or passenger in the front. Second and third-row seats have a very different ride quality, but they’re not usually part of the product design criteria. So, the methods Ricardo has developed are pertinent to CAVs when they arrive, but also to the conventional products of today.

Trials and testing

As a first step, the Ricardo team constructed a modular vehicle dynamics model including parameters known or thought to contribute to kinetosis. These included vehicle suspension set-up, driver inputs, human physical factors (i.e. weight, height, sex, age, health), mental factors (personal sensitivity to kinetosis, previous experience, alcohol consumption) and alsoseating position, seat type and cabin air quality. A simplified ‘crash test dummy’ style simulation shows the relative impacts of the vehicle’s motion on the occupant as measured by accelerometers under the tested scenarios, taking into account the different parameters.

This bio-mechanical model was then correlated and refined against real-life data collected in a small-scale on-road trial based at Ricardo’s Midlands Technical Centre near Leamington Spa in the UK. For this, participants were wired up with accelerometers, driven around three different routes, and observed on in-car video cameras.

Innovations engineer Michael Wheeldon explains: “There were two of us, each with a head-mounted camera, a head-mounted accelerometer, and an accelerometer on the seat. We
were holding a phone, which we were sometimes looking at, sometimes not, and we tried this sitting as a front and rear passenger.” Both Wheeldon and his co-participant – a much smaller woman – experienced higher accelerations in the rear seats, especially over speed
bumps. As expected, there were also differences between their responses to the various motions, highlighting the need to understand the effects of motion on different body types and sizes.

“Sitting in the back, all accelerations were higher for both of us, in line with how we understood the car’s design was focused around the front two passengers,” he notes. This exercise was a useful proof of experiment, he says: “We can see on the recorded video that with different styles of driving, you can elicit very different responses very quickly, and that there are a lot of different factors involved.” The resulting kinetosis prediction model, says Wheals, can be applied by OEMs during a vehicle’s attribute definition phase: “Within your simulation of the full vehicle, maybe four years before start of production when you can still make significant changes, this model can be applied: it could represent, say, an eightyear
old European passenger, male or female, to see how they will respond to the passive spring damper settings, the ride height, the roll stiffness and everything else that you’re defining.

“You can simulate a passenger with a validated and known propensity for kinetosis in different positions in the car, and try, for example, taking two roundabouts a bit quickly, or a cobbled road, which upsets children for all sorts of reasons.

“Our software modules can be built into the existing vehicle simulation,” adds Wheals, “but rather than trying to get seconds off a Nürburgring time, you’re thinking about how the ride can be softened or changed. The results could then be put in front of a panelof potential customers, to assess the relative importance of speed or sportiness against a comfortable, safe ride for their children.” OEMs can also use the model to decide and calibrate seating position, seating design, and other issues of cabin packaging, layout and ergonomics.
Yet the software can further be applied to directly benefit the vehicle’s end-user in continuous dynamic monitoring while driving, giving potential for a series of interventions to enhance comfort and prevent sickness. “The same algorithms could be used to avoid traditional compromises,” says Wheals.

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