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DORDT COLLEGE ENGINEERING DEPARTMENT A power steering system is essentially an op-amp made of gears, levers, shafts, and hydraulics. You can learn how a simple old-fashioned drag-link power steering system works from this video. It is a bit old but it's pretty good! Its simplicity makes it easier to understand. The goal of the power cylinder and control valve is to keep the steering shaft near the center of it's up-down travel. The power cylinder and control valve is not literally an operational amplifier, but there are similarities. Drag-link steering systems are now obsolete and considered dangerous. If you get in an accident that bends the drag link or the vehicle's frame relative to the drag link, you will lose control of the steering, even if the car is not badly smashed up. Modern cars use a rack-and-pinion system like this. Hydraulic power steering can be added like this. But that's also getting old-fashioned. How about electric, "servo-tronic" (marketing hype--but the product is real) power steering!Electrical and electronic systems are becoming more economically competitive than mechanical and hydraulic systems. There will always be a need for some mechanical parts (wheels, bearings, are examples) but internal parts are being replaced with electrical parts for lower costs and better performance. Most new cars sold in the last five years or so now have electric power steering. Modern electric power steering assist systems are coupled with the electronic stability control system. If a dangerous steering event is detected by the computer, say cornering so hard as to encourage a roll-over, then the amount of steering assist is instantly reduced by a measured amount to discourage the driver from turning that sharply. Such refinements would be much more expensive to accomplish with hydraulic power steering.You can even take it further and let the car park itself. Shoot, pretty soon cars will drive themselves. What an exciting time to be an engineer! Think of the cultural issues these possiblities present us. How about a self-driving school bus with no driver on board? That is possible with today's technology. Guess what? Op-amps, the real genuine electronic kind, are essential for this technology. (Click your browser's back arrow button to get back to the homework page.) |
