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Post by lowell on Nov 1, 2021 14:20:21 GMT -6
"Automotive Brembo goes brake-by-wire and eliminates hoses with new Sensify system By Loz Blain October 31, 2021"
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Post by James T. Kirk on Nov 1, 2021 15:27:57 GMT -6
I sometimes wonder if our cars can get too smart and reliant on computers and AI, especially given the recent chip shortage. I miss the days of being able to do just about anything to my own car. You can't even get to 90% of what's under the hood these days without completely pulling the engine.
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Post by lowell on Nov 1, 2021 15:50:43 GMT -6
I am encouraged by the move to having all the work done by the wheel. Braking, propulsion, steering, all being done by the wheel. The wheel is wired into the computer that receives input from the steering wheel, the accelerator pedal, the brake pedal and the "gear selector" (that last one would be forward, reverse and park.) With an electric motor, reverse is accomplished by reversing the motor movement direction (switching polarity). I am told that with a Prius, the electric motor does not need to step through gears to get from standing still to freeway speeds. Complete simplicity has arrived. The electric motor has so much torque that it requires a controller module, a limiter.
There is no pollution control system, no coolant system (water jacket - radiator), there is no huge motor under the hood, no transmission, no drive line, no differential. There will either be a large battery or a hydrogen fuel cell. I hope for the latter. The fuel cells up to now have problems with the platinum components breaking from temperature differences between off and operating. I expect that science engineering will find a solution for that soon. Perhaps platinum components can be joined with electrical conductors that stretch and contract more easily when temperatures change.
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rdlb2
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Posts: 14
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Post by rdlb2 on Nov 27, 2021 13:40:41 GMT -6
"The potential negatives here are fairly clear; with no physical connection between pedal and calipers, you'll be completely powerless to stop yourself if your car goes completely powerless, or there's a software glitch, or an EMP takes out your computers, which to be fair doesn't happen much these days in nicer neighborhoods. It's unclear what kind of failsafe measures can be built into this kind of system, although potentially there could be some kind of dead man's switch in the system capable of applying the brakes mechanically in the absence of electronic input."
Dead man's switch has been replaced with the term, "operator presence switch" in my field. I still used the former though. In my 46 years of working on MHE, I have watched electric drive and controls go from DC motor carbon pile controls, Pulse Width Modulation (PWM), resistor with contactors and switches, rectifiers and diodes with a mother board, contactor and switches, to DC separately excited motor controllers (SEM field and armature windings are controlled separately), to various forms of AC and their subsequent controllers. Batteries too have quite changed as well as onboard chargers and hard wired wall charging systems that monitor via computer one or more batteries at the same time. It was and still might be (financially if able) my desire to build an electric truck. I would still want my hydraulic brakes, yet use regen braking control to stop the vehicle. Our large E120 fork lift(12000#) use that to stop within the length of the forklift and its severity is adjustable. During regen with a 1600ah battery, I have observed over 200amps returned to the battery. I would have to do more research into the plausibility of any AC drive system I could build. Since I have retired, I no longer have access to software for the systems I am familiar with. The current market to purchase conversions is beyond my finances.
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Post by lowell on Nov 27, 2021 23:51:22 GMT -6
Planes have gone fly by wire. The military uses it successfully and commercial jets have used if for years. Automotive has been the last to use it. Brakes used to have one master cylinder but the front and rear brakes were given their own master cylinder as a safety backup. It was a good idea. The DC3 MAX is an example of the importance of a well designed software system, though. Part of the problem is that each manufacturer of brake by wire systems for automobiles has their own software that is proprietary, and they are not open to inspection and possible improvement. Perhaps the best of these will eventually be adopted by Federal regulators, so there might be an advantage to separate systems for now.
There are ways to make a backup for electronic brake control.
I have a friend that built his own plane. He has a private pilot licenses too. We went flying once. He says the pre-flight check list is a must. He says that nearly every malfunction for planes happens because the pilot skipped some or all of the pre-flight check list. Diagnostics can find vulnerabilities before they become an irreversible problem. When I became a long haul truck driver, I learned the safety check routine that commercial truck drivers are required to do before driving. The company I drove for bought new trucks on a regular basis. They didn't have trucks older than 5 years. Most trucks were replaced when they were 3 years old.
There may be a checklist the operator uses to verify the full functionality of the brake by wire system.
The computer system could be replaced in a similar schedule. It wouldn't be the most expensive component, and it could be easily replaced. that would include replacement of sensors and actuators. Typically components are tested for durability before they are integrated. A replacement well in advance of predicted failure would be important. These electronic changes to automobiles and trucks will need redundancy as well. Maybe it is best that the changes happen with the most expensive models first. Dependability of systems will be established before there is a major rollout.
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