Vehicles like Segway

[SEGsby]

The closest vehicle that I can find to the Segway, in terms of the electric motors directly actings as the breaks-- is the QED Mini Cooper Prototype.

Each wheel has it's own motor:

http://www.treehugger.com/files/2006...ybrid_mini.php

SEGsby

[runway10]

Thanks Segsby!

This is exactly what I'm looking for! One of those that are streetlegal would put an end to the mechanical brake issue...

[joe]

Originally Posted by runway10

This is exactly what I'm looking for! One of those that are streetlegal would put an end to the mechanical brake issue...

Agreed. But... I'd like a parking break at least! Note the wooden wheel chocks in the picture!

--
Johannes

[BillPaxton]

that article is almost a year old - I think it was only a concept. My car (Honda Civic Hybrid) claims to be the current 'highest MPG Hybrid' at 51mpg - don't know if that's true about it being the highest but I can tell you with my lead foot and 37 mile commute to work, I average 46mpg. If what Honda says is true tho, then either this article has factual problems and should not be considered a good source of data for a debate or it does not yet exist in production which again makes it not your best candidate. The Zap Obvio on the other hand(http://www.zapworld.com/ZAPWorld.aspx?id=388) is 100% electric - not a hybrid - and it is currently in production. Also - regenerative braking does not mean lack of a disc/caliper system as you will note in the Obvio pages, and I doubt any auto manufacturer would limit braking on a car that weights over 1000lbs to reversing current to motors. Half a ton capable of moving 70MPH needs some serious stopping power.

I'm also not sure a legislator would buy the leap from electric car to Segway even if it were 100% current induced braking - weight and size dissimilarity is enough to derail the argument if the legislator hearing you decided the debate needed to end quickly. I'm not saying don't try, I'm just saying don't just consider your logic being correct when arguing with a politician, consider how a politician can make your logic look fuzzy. To paraphrase Nick Naylor, "I didn't have to [prove I wasn't wrong]. I proved that you're wrong, and if you're wrong I'm right."

[KSagal]

Originally Posted by joe

Agreed. But... I'd like a parking break at least! Note the wooden wheel chocks in the picture!

--
Johannes

That is the hallmark of this cutting edge technology. Segway uses the same parking "assistors".

[GadgetmanKen]

I personally wouldn't want electric braking on anything. Driving many 2nd hand, third gen autos I can think of numerous times when my car had died, or stalled and had to stop suddenly. With hydraulic brakes its no problem till you have the air boost systems in later models. With no air from the running engine its a guess if you will stop in time when they stall. Now, I can remember times when I had a loose or dying battery connection and the car stalled say after hitting a pothole, if I had electric brakes and had a loose connection, or an overloaded, or weak battery system I think I would be in a heap of trouble. As for having magnetos built into each wheel, rim, brake drum, or rotor, would be nice in the effect of regeneration storage power, but I would not rely on electronic brakes. I think of electronic brakes as in a Segway (which is basically switching the current the opposite direction) to stop you is OK for a Segway but not a car. Its just got too much weight and mass and momentum. For electric brakes to work IMO they would have to be similar to the way the new antilock brakes work with the multiple pulses say of a solenoid against the pads to work. But there in again, if you have a battery short, or connection cut off at the wrong time you're toast. Having electric assist for anti lock would to me be a better solution to add to hydraulic brakes. I'm from the old school.

[KSagal]

Originally Posted by GadgetmanKen

I personally wouldn't want electric braking on anything. Driving many 2nd hand, third gen autos I can think of numerous times when my car had died, or stalled and had to stop suddenly. With hydraulic brakes its no problem till you have the air boost systems in later models. With no air from the running engine its a guess if you will stop in time when they stall. Now, I can remember times when I had a loose or dying battery connection and the car stalled say after hitting a pothole, if I had electric brakes and had a loose connection, or an overloaded, or weak battery system I think I would be in a heap of trouble. As for having magnetos built into each wheel, rim, brake drum, or rotor, would be nice in the effect of regeneration storage power, but I would not rely on electronic brakes. I think of electronic brakes as in a Segway (which is basically switching the current the opposite direction) to stop you is OK for a Segway but not a car. Its just got too much weight and mass and momentum. For electric brakes to work IMO they would have to be similar to the way the new antilock brakes work with the multiple pulses say of a solenoid against the pads to work. But there in again, if you have a battery short, or connection cut off at the wrong time you're toast. Having electric assist for anti lock would to me be a better solution to add to hydraulic brakes. I'm from the old school.

I agree with some of your comments, but would put in a few caviots...

A weak or poorly maintained mechanical system, as you describe is hardly a good schematic for design, of course any system, regardless of what it is, when the operator knows it is weak and faulty and uses it anyway, puts that operator at risk...

Now, a system should be designed to minimise that risk, regardless of the operator, so the system should require a self check before allowing motion, and at regular intervals as well, and some of what you described will be minimised...

Next, the battery on an internal combustion engine car is not a primary system, in that you can remove the battery, push jump the car, and it will work fine, presuming all the other systems are working. If the battery is weak, because the alternator is weak and it is running the engine from the battery instead of it's own electrical power generation, as it is designed to do, then your problem is still one system that is bad, causing another to weaken, and again, self check before operation is allowed would minimise the exposure.

NOw, I have run a car long distances with weak charging, where I was aware enough to always charge the car before leaving, as a back-up... But that was decades ago, in a muscle car from the '60s. Most of us do dumb things as kids, and as we get older, we are supposed to do less of them... (I say, 'supposed to' because you may recall some of my skydiving stories, etc...LOL)

A major point to consider would be that of the electrical brakes on an electrical vehicle. The electrical brakes you described are binders. Currently, most binding brakes have a piston of some sort that applies pressure to the moving (Spinning with the wheel) part with a non-moving pad. THis is in drum brakes, disk brakes, transmission brakes (Just the drum is on the drive shaft instead of the wheel) and on the caliper style brakes on some bikes. By including an electric movement piston on this type of a brake, you simplify the electrical requirement but also add an easy place to fail.

Binding brakes require movement without drive, or coasting. Segways cannot coast. Because of this, the example you offer is not directly applicable to segways, but it is to cars, which do coast.

In order for cars to be available for a direct comparison, cars do not need to have electric brakes added, they need to have the ability to coast removed.

Now, I can imagine that it is not too hard, although I have never tried, to step on an upright segway, that is not turned on, head it down a hill, and balance yourself on it. I know people who can ride skate boards, and even unicycles, and imagine it is possible. In that case, more redundant braking systems may be in order.

One last point. If you really wanted to design an all electric braking system for a car, that is not too differently geared to what is on the road now, I would simply build the regeneration of the power directly into the brake system, similar to a magnito system... A magnetic system that generates power based solely on the rotation of the wheel is possible, and it would generate enough power to appy to that brake, and each would have enough storage to do just that. Excess power generation from each collector could be sent to a communal storage battery, but if each brake on each wheel had some storage capacity for one stop, then your problem would go away, in that each brake can be self powered, and not depend on the power system from the vehicle.

[GadgetmanKen]

A weak or poorly maintained mechanical system, as you describe is hardly a good schematic for design, of course any system, regardless of what it is, when the operator knows it is weak and faulty and uses it anyway, puts that operator at risk...

Most the time I knew it was going bad or was faulty, but the funds to fix it just wasn't there. It was a deal with as you go type of thing. Ya know?

Another example is a 93 Buick Centry my wife had that we bought at two years of age. At about the eighth year it kept dying, stalling whenever it hit a hard bump, but not always. It was intermittent. We took it to two different dealerships and couldn't get it to stall anytime when hitting bumps. We all thought my wife was nuts. We couldn't get it to do it on demand. They couldn't figure it out. We finally took it to a good local garage mechanic and he found out what it was. It had a short in the wiring harness inside the steering column where the brights, wiper and speed control, ignition were. Changed the harness with a new one and it stopped. They eventually had a recall on that part.

As for the bad connection on the battery. Sure you can take off the positive post off while the car is running and the generator, alternator takes over, but take the ground loose and the car will die.

But a good ole self check diagnostics wouldn't hurt, either..

[citivolus]

I don't think all-electric regenerative brakes are adequate for stopping a highway speed vehicle. Resorting to a little quick math, as I am wont to do, consider a very light 1100 lb vehicle going 67 mph. Converting to metric, because I picked numbers that look nice that way, gives 500 kg and 30 m/s. In order to stop this requires either storing or dissipating 225,000 Joules. If we assume a normal stop to be 0.5 g and a panic stop to be 1.0 g, this gives us stopping times of 6.12 seconds and 3.06 seconds respectively. Since a Watt is a Joule / second, we find through simple division that the normal stop has go get rid of 36,765 Watts and naturally the panic stop is going to be double that. While you might get 50-100 HP out of batteries, putting it back in is somewhat harder.

The Segway is rather different. Assuming the total weight of a fully loaded Seg is about 150 kg (~330 lb) at it's top speed of 5.6 m/s (~12.5 mph) has 4704 Joules to eliminate. Again, using the same 0.5 and 1.0 g standards just for comparison, stop times are 1.14 and 0.57 seconds meaning the power is a much more manageable 4116 and 8232 Watts. That still isn't to say that you can jam that much power in a battery just that it is much more manageable. Now, I don't know the real numbers but I'm sure the actual stopping time of a Segway has been discussed here before and anyone really interested can perform the experiment themself.

[KSagal]

Here's one for the Venice beach crowd...

You could use the numbers for a highway capable vehicle, and use all that extra wattage that needs to be instantly dissapated by stunning everyone within line of site distance with a large stunning field, just in case they were thinking of making a disparaging remark about your electric vehicle...