Hobby Humanoid Robot KHR3HV Rides Bike At 10k/h

An anonymous reader points out a fun robot project from Japan, writing: "The robot pedals with its feet at variable speed. The steering is done by the robot hands as with a normal bike, and remote controlled by a human. Stability is achieved by relying on the inertial centrifugal effect of the front wheel and on a gyro aided by a PID controller that takes over steering when driving in a straight line. Seems like when the robot steers his arms he also bends the waist leaning a bit into the turn. Braking is achieved by taking the feet off the pedals and pointing them down to the ground using the metal feet as friction breaks."

Comments

Slashdotted

[definate]

http://robosavvy.com.nyud.net/forum/viewtopic.php?p=32542

URL for video

[definate]

http://www.youtube.com/watch?v=SqBw7XapJKk

Stability is NOT achieved that way.

[Jane Q. Public]

A number of very thorough studies have been done. Neither "inertia" or "centrifugal effect" from either front wheel or rear contribute anything significant to the stability of a bicycle. The fact is that even today, we do not fully understand the phenomenon. The only thing we are sure of is that it does not work the way most people think it does.

Re:Stability is NOT achieved that way.

[Col Bat Guano]

We do understand how to maintain balance on a bike.

People steer into the continual tiny falls that happen all the time, actively steering the bike upright.

Re:Stability is NOT achieved that way.

[flyingfsck]

It is true that the gyro effects are not needed to ride a bike. That is why one can ride a bike with tiny wheels just as well as one with big wheels. However, at high speed it does have a very noticeable effect and does contribute to stability - for good or worse if your wheels are badly balanced. Once you reach speeds of 80km or over, the gyro effect becomes very strong indeed - you can literally hang off the side of a bike and not fall immediately, it will just turn slowly - been there.

Re:Stability is NOT achieved that way.

[definate]

Pretty sure motorcycles don't work unless at least 1 wheel (often the front wheel) is off the ground.

Re:Stability is NOT achieved that way.

[thestuckmud]

This paper" states that "contrary to common belief, gyroscopic forces play only a limited role in balancing and steering". The "feel" of a bike (pedal or motor) is said to be dominated by "trail", and aspect of steering geometry; gyroscopic torque is "non-negligible", but "much smaller than trail torques".

Gyroscopic steering is said to assist no hands bicycle riding, but I'm not a motorcycle rider and don't know about wheelie stability.

Re:Stability is NOT achieved that way.

[subreality]

Actually, no, it's still not the gyroscopic effect keeping you upright. The caster and trail (parameters of a bike's front suspension geometry) result in the bike having a self-balancing effect: as you lean to the right, it wants to steer right, and the centrifugal force of the turn pushes you left, keeping you from falling over. This works fine with zero-mass wheels that do not have any gyro effect.

At low speeds this effect is not enough for stability: with no active control it wants to turn constantly, and follows a squiggly, unsettled path. At mid-speeds it will want to turn, but they will be stable turns. At high speeds the bike becomes over-stable: if you let go mid-turn, the bike will automatically straighten itself out and return to a stable straight line. This is contrary to what you'd expect from the gyro effect, which would be to hold the bike leaning into the turn.

The gyro effect does exist, but its really not that strong compared to your weight and all the other forces involved.

Re:Stability is NOT achieved that way.

[rapiddescent]

BMX will lock the wheels when performing tricks (in mid air) - it makes the bike a lot less sluggish to manoeuvre. Mountain bike freeriders/dh'ers will leave the wheels running (usually subconsciously) to help keep the bike pointing in roughly the right direction. [try doing a long fast jump with the wheels locked and it definitely loosens everything up - usually ending in a big crash!] -- can't find any internet citations - except that I do it myself.

Re:Stability is NOT achieved that way.

[thestuckmud]

Forget about the handlebars for a moment. The fact is that you can't turn to the right unless your center of mass is to the right of the bicycle's wheels. If you try to turn from a stable position, you will soon find yourself fall to the left and will crash unless you correct your course by turning left. That's the crucial point.

OK, so how do you get your center of mass to be positioned to the right? Most riders do so by countersteering - turning slightly left first. Most riders are not conscious of this process. There are other ways. You might hop the bike to the left, or tilt the bike and rely on the curvature of the tires. As a somewhat proficient unicyclist, my eyes have been opened to the variety of subtle influences that can influence the behavior of a wheel, so, sure, pushing handlebars is not the only way to turn.

FWIW, I built myself a nice road bike a little while ago with a subtly more stable frame (combination of wheelbase, angles, trail) than is currently in fashion. It is quicker at turning than my old bike because I can apply a lot of countersteering while keeping better control through the middle and exit of a turn.

Speed not a problem

[antifoidulus]

Unfortunately most Japanese tend to ride their bikes at about 10km/h, so speed won't be an issue for this robot.....

Re:only 6.2 miles /H

[Anonymous Coward]

a robot rode a bike without falling over...... and you're upset he didn't go faster?

Hey editors, watch your homophones

[voidptr]

Brakes. A device that stops the motion of a moving part is called a brake.

k/h?

[Sami Lehtinen]

K/H? I did WT*. Among Techies, this is major fail. https://secure.wikimedia.org/wikipedia/en/wiki/International_System_of_Units

Re:k/h?

[Noughmad]

Correct Fact: People in metric countries actually talk in km/h.

Some suggestions

[atari2600a]

Make it's face either Hello Kitty or a mecha drill, put it on a scale Honda Super Cub & fit it with a scale Malaysian stereo kit that blasts the J-poppiest happy hardcore you can find. Or YMCK. Then I'm sold.

Re:you steer by leaning, not turning the handlebar

[subreality]

You should read your link more carefully. Leaning is necessary to turn, but it is not what causes you to turn.

Read the next section. If you want to turn right, you briefly turn the handlebars left. That leans you to the right. You then turn the handlebars to the right, and enter a stable right turn. To exit the turn, you turn right a little harder, which brings you vertical again, and then you straighten out.

Re:you steer by leaning, not turning the handlebar

[Hentes]

Turning the handlebar helps, but it's not necessary. That's why you can ride a bike without hands, as leaning will cause the handlebar to turn by itself.

10 k what?

[jb_nizet]

10 k inches? meters? feet? yards?
k means kilo (1000). It's not a distance unit. I guess it's 10 km (1000 meters). Isn't it basic stuff that every nerd learns at school, at the age of 8 or 9 years?

A data rate of just 10000 bits per hour = 3 bit/s

[Anonymous Coward]

I, for one, welcome it that the article tried to mention metric units. But c'mon. 10k/h? That means 10 kilograms per hour or what?

Re:A data rate of just 10000 bits per hour = 3 bit

[tsa]

It means 10000/h.