Understeer, oversteer and steering in general

I promise that this will be my last post on this subject. Well, I shouldn’t promise, but I don’t want to change the fundamental nature of my blog. Driving is a basic life-skill in modern societies and people die from it, therefore it’s worth a bit of print. In fact, people receive horrendous injuries, comparable to what one might get in a war, but few of us ever think about that when we get into a car, otherwise we probably wouldn’t.

Airline pilots go through training drills regularly, which is why they can cope with most things that try to spill them out of the sky. In the case of driving, which most of us do above a certain age, the only training we get, beyond how to operate a vehicle and the local road rules, is what we learn ourselves. I’m a firm believer that we should be teaching kids how to drive in schools, and teaching them so-called advanced driving skills like how to brake and swerve at the same time. I know at least one driver who is convinced that if she swerves she will roll the vehicle, so she’s probably the norm rather than the exception. I know another driver who won’t drive on the shoulder because the prospect scares him to death. I’ve done both on more than one occasion and avoided certain disaster on each occasion.

So what can I possibly write on a blog that may help? Well I can explain the dynamics of a car when cornering because that’s the essence of driving in my view. I believe a car should be an extension of your mind and body, because in some ways it is. You think and act which produces effects that change direction and change speeds, often at the same time, in response to visual and sensory stimuli. The sensory stimuli include your sense of balance, the strain on the muscles of your neck, the weight of the steering wheel and the pressure you feel on the brake pedal. What’s more, you can’t see the extremities of your vehicle, let alone where the wheels touch the ground, yet you can place it on the road with centimeter precision, out of sheer practice.

Of course, some cars do this better than others, and, unfortunately, a lot of cars are designed and manufactured to do the opposite: isolate the driver from the driving experience as much as possible, so they can indulge in the illusion that the car does the driving for them. I guess this makes me old-fashioned; I even drive a manual.

Most cars are designed to understeer when pushed because that’s what most drivers expect and what they are comfortable dealing with. Understeer is technically when the front wheels slip more than the rear and oversteer is the opposite when the rear wheels slip more than the front. In real world terms, understeer is when the front of the car runs wide in a corner and oversteer is when it feels like the back is trying to overtake the front, and, in extremis, can lead to the car spinning. Spinning is not so bad an outcome, by the way, because the car loses its energy and doesn’t go anywhere, like sliding into a tree or another car. I’ve seen people spin cars, unintentionally, and they came out unscathed. It’s also why racing drivers spin their cars, intentionally, when they lose control, to try and lose as much kinetic energy (speed) as quickly as possible. These days, most cars have ESP (electronic stability programmes) or some such acronym, so spinning a car may be next to impossible. I don’t know, I haven’t tried recently.

Getting back to understeer, the antidote is pretty simple: you take your foot off the throttle or apply more steering lock or both, both of which are the opposite to what created it in the first place, so it’s easy and intuitive to do.

Some cars are designed to be neutral or well balanced, which means, that under ideal conditions, they let go at the front and rear simultaneously. This is my own personal preference, because you can change it from understeer to oversteer or vice versa. You may ask: what could possibly be the advantage of oversteer? Well, mild oversteer, as opposed to snap oversteer, can help to point the car into the corner, and well-balanced cars facilitate this in a very non-threatening and confidence-building manner. In most driving circumstances, there are only 2 inputs involved in cornering: steering and throttle. Throttle allows you to adjust the car and, in combination with steering, you can finesse it around a corner without lurid slides or screeching tyres, just fluid and efficient progress that impresses people rather than scaring them.

Now, it needs to be pointed out that front-wheel-drive cars are often particularly adept at this steering on the throttle, as it’s called, and lift-off oversteer is possible. In other words, you may get dramatic oversteer from simply lifting off the throttle sharply, though, with the electronic intervention that all modern cars have, this is unlikely. Rear-wheel-drive cars do the opposite and can be made to oversteer with extra application of the throttle, but again, modern electronics, makes this unlikely in today’s cars.

Finally, I wish to point out something that is not generally spoken or written about, and that is that steering is one of those skills that the brain delegates to the subconscious, as it does other skills like walking, or hitting a ball with a cricket bat or a tennis racket or a baseball bat. Fingering skills that musicians learn also fall into this category so they become automatic and we can do them without thinking about them. In fact, the brain does this, out of practice, so it can think about more important things.

So I don’t believe that anyone thinks about steering when they drive a car around a corner – I know I don’t – I just do it. What I think about when approaching a corner is what gear I should be in, whether I brake or just lift off the throttle, so I’m only thinking about things that affect my speed of entry. I never think about where I should put my hands on the wheel or when I should turn in or even where I should apex the corner – I do all of that automatically. But speaking about speed, one of the worse things you can do is look at the speedo when you’re entering a corner – I’m sure a lot of accidents have occurred because of that – yet no one ever tells you. It’s like taking your eye off the ball. If you want to know what speed you’re doing around a corner, then look at the speedo on exit, not on entry. Also, possibly the worst thing you can do is enter a corner with a preconceived speed in your head, and have it on the speedo before you commit. You should be able to judge what speed to do around a corner without looking at the speedo – in fact, I think that’s fundamental.

Lastly (I know I’ve already said finally) a lot of ink has been used and many words spoken on the technique you should use for steering. There are 2 favoured methods: feeding the hand and the racing driver technique. I think there’s a place for both of them, but I have another which I evolved myself without any instruction. When I was learning to drive (in Oz) driving instructors were teaching what I call the shuffle technique, whereby student drivers were shuffling the wheel in short strokes in order to keep their hands on opposite sides of the wheel at all times. I was reminded of this recently when I was a passenger in a car where a woman of my vintage was doing a 3 point turn using this very technique. Now, it’s not her fault – it’s what she was taught, and because the brain delegates this to the subconscious she’s condemned to do it for the rest of her driving life.

What I believe these instructors were trying to teach was the ‘feed-the-hand’ technique, whereby we turn one hand over the top of the wheel - left hand for right turning and right hand for left turning – into the opposing hand which remains stationary. Thus, when we have applied the correct lock, our opposing hand is in the correct position to control the car. By correct position, I mean it’s ideally placed for maximum leverage and control which is on the side of the wheel. In fact, this is the best position to have both hands when we are driving straight ahead as well. In some cars there are little indents for the thumbs that facilitate this position when the steering wheel is in the straight ahead position.

And this is the position that’s advocated in the so-called racing driver technique, only they don’t change their position when they turn the wheel. I'm a firm believer in adopting the racing driver technique as a default position because it’s the best place to have your hands if you need to swerve. When you swerve, it’s always a reflex action and you don’t have time to change positions or move your hands on the wheel.

However, when approaching a corner, I move one of my hands over the wheel (depending which way I need to turn) so it automatically applies the right amount of lock when it returns to the default position (on the side) with wheel in hand. In other words, instead of feeding my hand, I grab the amount of wheel I think I’ll need. The difference, in practice, is that with feeding-the-hand, one hand ‘hands over’ to the other at some point in the process; whereas, with my technique, the handover occurs before you actually turn the wheel.  Now, I’m not the only one who does this, but no one taught me: it just evolved and I do it without thinking. It has the advantage that subconsciously I must intuit how tight the corner is as I judge how much lock I need before I enter the corner. Once I’m in the corner, my hands (both of them) are on opposing sides of the wheel which gives me best control. The only time I use the feed-the-hand technique is when I know I need more than one handful of lock, and I have to reach one hand over the other, which is the case for most suburban intersections.

There is one other advantage in a well-balanced or neutral car and that is that if it slides it will correct itself due to the underlying physics – the car will intrinsically seek neutrality. In other words, in an oversteer slide I will simply let go of the steering wheel and the car will correct itself. So why should a car slide? Well, it depends on the conditions, like mud or snow or slush, so I’m not talking high speeds. Even with electronic intervention, slides are possible if the conditions are diabolical enough.

I haven’t mentioned how important good tyres are – they are your lifeline – and how equally important it is to maintain their air pressure. I put air in mine about every 1,000km (600 miles) or every second time I fill up with petrol. They lose around 2-3psi in that time, so I put in an extra 2psi more than what is recommended by the manufacturer. Imagine how much you would care about your tyres and air pressure if you only had 2 wheels instead of 4.

Addendum: I need to say something about cruise control. In Australia, cruise control is very popular, partly because people use it to avoid breaking speed limits. Australia has the lowest tolerance to exceeding speed limits of probably anywhere in the world. Having said all that, I never use cruise control, because I have a psychological problem with giving up that aspect of the car’s control – I like to know I’m controlling the car’s speed all the time. I know that makes me an outstanding exception. The problem with cruise control, as I see it, is that we give up our sense of speed - we delegate it to the car - though I consider it to be essential to driving. By sense of speed, I mean we know longer make judgements about how fast we should be going, because we no longer are allowed to.

Addendum: Can I just say that probably the best book on this subject is How to Drive by Ben Collins, aka The Stig (from Top Gear). Unlike me, he's a professional driver. He was also a stunt driver for at least one James Bond movie.

The Physics of Motorcycling

Since I wrote a post on the Physics of Driving (March 2014), it seems only logical and fair to write one on the physics of motorcycle riding. The physics is more complex and counter-intuitive, but it’s also more intriguing.

In both cases the driving force (excuse the pun) is gyroscopic dynamics, though, in the case of a motorcycle, it’s both more central and more controlling. I can still remember the first time I went round a decent corner (as opposed to a street intersection) on a motorcycle and felt the inherent weightlessness it generates. This is the appeal of riding a bike and what separates the experience viscerally from driving a car.

As I’ve already explained in my previous post on driving, it’s the muscle strain on our necks that tells us how hard we are cornering, whether we are in a car or on a bike, though the effect is reversed from one to the other. In the case of a car we lean our heads into the corner to balance the semi-circular canals in our ears, and our neck muscles subconsciously tell us what the lateral force is in a subjective sensory manner. In the case of a bike we lean our bodies and keep our heads upright - because we feel effectively weightless - but the strain on our neck muscles is exactly the same, even though it is reversed.

So that explains how it feels but it doesn’t explain how it all works. The physics is not easy to grasp, but the effect is relatively easy to explain, even if one doesn’t understand the dynamics behind it, so please persevere with me. There is a second law of angular momentum, which effectively says that if you apply a torque around an axis perpendicular to the rotating axis, you will get a rotation around the third axis, called precession. One usually draws diagrams at this stage to demonstrate this, but I can do better: I will give you an example that you may be able to perform at home.

A surveyor’s plumb bob works best to demonstrate this, but a bicycle wheel can work as well. Take a plumb bob with its string wrapped around it, hold it horizontally so the wound string is vertical, then let it go while holding the end of the string. As it falls the unwinding string makes the plumb bob spin about its horizontal axis, but when it gets to the end of the string, it doesn’t fall over.  It precesses, giving the impression of weightlessness. This YouTube video demonstrates what I’m talking about rather dramatically with a heavy flywheel, and its sequel demonstrates it even better, and explains the so-called weightless effect. And this video explains the physics concerning the 3 axes using an ordinary bicycle wheel on the end of a rope (which you may be able to do yourself) .

So what has all this physics got to do with riding a motorcycle? It’s what gets you around a corner – as simple as that – but the way it does it is completely counter-intuitive. To get the bike to lean over we apply a torque, via the handlebars, perpendicular to the rotational axis, only we apply it in the opposite direction to what we might think. Basically, if you push on the bar in the direction you want to turn, it will lean over in that direction. By ‘push’ I mean you push on the left bar to lean left and on the right bar to lean right. This is the counter-intuitive part, because we would think that if we pushed on the left bar the wheel would turn right. In fact, I’ve argued about this with people who ride motorbikes, but I know it’s true because, I not only understand the physics behind it, I put it into practice in over a decade of riding.

Now, when the bike leans over, it behaves exactly the same as the fly-wheel in the videos, and, under the force of gravity, the bike precesses around the corner, generating a feeling of weightlessness at the same time.

So that’s the core of the physics of riding a motorcycle but there’s more. In a car you can swerve and brake at the same time, as any advanced driving course will teach you. But on a bike you can do one or the other but not both. If you brake in a corner, the bike will ‘stand up’ and there is nothing you can do about it. This is different to simply closing the throttle, when the bike will tighten its line (turn tighter). Now, why this quirk of physics may seem catastrophic, it’s what allows you to brake in a corner at all. You see the bike will still follow the same curved trajectory while it’s slowing down, and it does it without any intervention from you except for the application of brakes.

The other laws of physics I explained in my last post, regarding the inverse law of speed versus rate-of-change of direction, and the braking distance following the speed squared law still apply. In other words, it takes twice as long to change direction at double the speed, and it takes 4 times the distance to brake at double the speed.

Why consciousness is unique to the animal kingdom

I’ve written a number of posts on consciousness over the last 7 years, or whenever it was I started blogging, so this is a refinement of what’s gone before, and possibly a more substantial argument. It arose from a discussion in New Scientist  24 May 2014 (Letters) concerning the evolution of consciousness and, in particular the question: ‘What need is there of actual consciousness?’ (Eric Kvaalen from France).

I’ve argued in a previous post that consciousness evolved early and it arose from emotions, not logic. In particular, early sentient creatures would have relied on fear, pain and desire, as these do pose an evolutionary advantage, especially if memory is also involved. In fact, I’ve argued that consciousness without memory is pretty useless, otherwise the organism (including humans) wouldn’t even know it was conscious (see my post on Afterlife, March 2014).

Many philosophers and scientists argue that AI (Artificial Intelligence) will become sentient. The interesting argument is that ‘we will know’ (referencing New Scientist Editorial, 2 April 2011) because we don’t know that anyone else is conscious either. In other words, the argument goes that if an AI behaves like it’s conscious or sentient, then it must be. However, I argue that AI entities don’t have emotions unless they are programmed artificially to behave like they do – i.e. simulated. And this is a major distinction, if one believes, as I do, that sentience arose from emotions (feelings) and not logic or reason.

But in answer to the question posed above, one only has to look at another very prevalent life form on this planet, which is not sentient, and the answer, I would suggest, becomes obvious. I’m talking about vegetation. And what is the fundamental difference? There is no evolutionary advantage to vegetation having sentience, or, more specifically, having feelings. If a plant was to feel pain or fear, how could it respond? Compared to members of the animal kingdom, it cannot escape the source, because it is literally rooted to the spot. And this is why I believe animals evolved consciousness (sentience by another name) and plants didn’t. Now, there may be degrees of consciousness in animals (we don’t know) but, if feelings were the progenitor of consciousness, we can understand why it is a unique attribute of the animal kingdom and not found in vegetation or machines.

How should I live?

This is the 'Question of the Month' in the latest issue of Philosophy Now (Issue 101, March/April 2014). Submissions need to be 400 words or less, so mine is 400 words exactly (refer below).

How should I live?

How I should live and how I do live are not necessarily the same, but having aspirations and trying to live up to them is a good starting point. So the following is how I aspire to live, which I don’t always achieve in practice.

The most important point is that no one lives in isolation. The fact that we all, not only speak in a language, but also think in a language, illustrates how significantly dependent we are on our milieu. What’s more, from our earliest cognitive experiences to the remainder of our lives, we interact with others, and the quality of our lives is largely dependent on that interaction.

Everyone seeks happiness and in modern Western societies this universal goal is taken for granted. But how to achieve it? A tendency to narcissism, tacitly encouraged by the relatively recent innovation of social media, can lead to self-obsession, which we are particularly prone to in our youth. Socrates famously said (or so we believe): ‘The unexamined life is not worth living.’ But a thoughtful analysis of that coda, when applied to one’s own life, reveals that we only examine our lives when we fail. The corollary to this is that a life without failure is a life not worth living. And this is how wisdom evolves over a life’s experiences: not through success or study but through dealing with life’s trials and tribulations. This is reflected in virtually every story that’s been told: how the protagonist deals with adversity, be it physical or psychological or both. And this is why storytelling is universally appealing.

So how should I live my life? By being the opposite to narcissistic and self-obsessed. By realising that every interaction in my life is an opportunity to make my life more rewarding by making someone else’s life more rewarding. In any relationship, familial, work-related, contractual or whatever, either both parties are satisfied or both are dissatisfied. It is very rare that someone achieves happiness at someone else’s expense, unless they are competing in a sporting event or partaking in a reality TV show.

There is an old Chinese saying, possibly Confucian in origin: If you want to know the true worth of a person, observe the effects they have on other people's lives. A true leader knows that their leadership is not about their personal achievements: it’s about enabling others to realise their own achievements.

Pitfalls of a Democracy

The latest issue of Philosophy Now has as its theme, ‘Democracy’, with a number of articles on the subject covering Plato to contemporary politics. In particular relevance to this post, Anja Steinbauer ‘explains why Plato had problems with democracy.’ I won’t discuss her article at length, but early on she points out that ‘…it all comes to a head with Socrates: Athenian democracy didn’t like Socrates, which is why the troublesome thinker was democratically put to death.’ The reason I paraphrase this is because it has dramatic relevance to current political events in Australia.

On a recent issue of 4 Corners, whistleblowers and video footage tell us what the government was unwilling to reveal regarding not so recent events at a detention centre for refugees on Manus Island, Papua New Guinea, where an asylum-seeker was killed during a riot. The programme reveals the deeply flawed inhumanity of this particular government policy which was originally introduced by the previous (Labor) government and is now being brutally pursued by the incumbent (Liberal) government. Both sides of politics endorse this policy because it’s a vote-winner and, in fact, the last election campaign was dominated by who could be more successful in ‘stopping the boats’ (containing asylum-seekers) as if we are suffering from a wartime invasion.

The relevance to Steinbauer’s insightful commentary on Plato and Socrates is that, with the explicit support of the general public, a government can execute policies that directly contravene the human rights of people who have no political representation in that country. In essence, we are guilty of inflicting both physical and emotional trauma on people; an action we would condemn if it was being done somewhere else. In short, a democratic process does not necessarily provide the most ethical and moral resolution to a dilemma.

The other side to this, is the airing of the programme itself. Only a healthy democratic society can foster a journalistic culture that can openly criticise government policies without fear of retribution.

The physics of driving

This is quite a departure, I know, but one of my hobby-horses is how little people know about the physics of driving. Unlike our man-made road rules, the laws of nature are unbreakable, so a rudimentary knowledge can be useful.

But what prompted me to write this post was a road test I read of the new, upmarket Infiniti Q50 in EVO Australia (March 2014). The big-selling feature of the Infiniti Q50 is its so-called ‘direct adaptive steering’; a world first, apparently for a production car (as opposed to a prototype or research vehicle). It’s a totally ‘fly-by-wire’ steering system, so there is no mechanical connection between the helm and the front wheels. Personally, I think this is a dangerous idea, and I was originally going to title this post, rather provocatively, “A dangerous idea”. Not surprisingly, at least to me, the road-tester found the system more than a little disconcerting when he used it in the real world. It was okay until he wanted to push the car a little, when the lack of feedback through the wheel made him feel somewhat insecure.

There are gyroscopic forces on the front wheels, which naturally increase with cornering force and can be felt through the  steering wheel. The wheel weights up in direct proportion to this force (and not the amount of lock applied as some might think). In other words, it’s a linear relationship, and it’s one of the major sources of determining the cornering force being generated.

I should point out that the main source of determining cornering force is your inner ear, which we all use subconsciously, and is why we all lean our heads when cornering, even though we are unaware of it. It’s the muscle strain on our necks, arising from maintaining our inner ear balance, that tells us how much lateral g-force we have generated. On a motorcycle, we do the opposite, keeping our heads straight while we lean our bodies, so the muscle strain is reversed, but the effect is exactly the same.

Therefore, you may think, we don’t need the steering wheel’s feedback, but there is more. The turn-in to a corner is the most critical part of cornering. This was pointed out to me decades ago, when I was a novice, but experience has confirmed it many times over. Yes, the corner can change radius or camber or both and you might strike something mid-corner, like loose gravel, but, generally, if the front wheels grip on entry then you know they will grip throughout the rest of the corner. This is the case whether you’re under brakes or not, wet or dry surface. It’s possible to loosen traction with a heavy right foot, but most cars have traction control these days, so even that is not an issue for most of us. The point is that, if the front wheels grip on turn-in, we ‘feel’ it through the steering wheel, because of the gyroscopic relationship between cornering force and the weight of the wheel. And cornering force is directly proportional to the amount of grip. The point is that without this critical feedback at turn-in, drivers will be dependent on visual cues to work out if the car is gripping or not. What’s more, the transition from grip to non-grip and back won’t be felt through the wheel. If this system becomes the engineering norm it will make bad drivers out of all of us.

While I’m on the topic, did you know that at twice the speed it takes four times the distance to pull up to a stop? Perhaps, you did, but I bet no one told you when you were learning to drive. The relationship between speed and braking distance is not linear – braking distance is proportional to the speed squared, so 3 times as fast takes 9 times the distance to stop. This is independent of road surface, tyres and make of car – it’s a natural law.

Another one to appreciate is that at twice the speed, changing direction is twice as slow. There is an inverse relationship between speed and rate of change of direction. This is important in the context of driving on multi-lane highways. A car travelling at half the speed of another – that’s overtaking it, say – can change direction twice as fast as the faster car. This is also a law of nature, so even allowing for superior tyres and dynamics of the faster car, the physics is overwhelmingly against it. This is why the safest speed to travel on multi-lane highways is the same speed as everyone else. An atypically slow car, in these circumstances, is just as dangerous (to other motorists and itself) as an atypically fast car.

Addendum: I also wrote a post on the physics of riding a motorcycle.