Power Steering (Electric)

[Kinarfi]

Moved all the Posts related to Electric Power Steering over to this new topic, 2009-03-24.

Lenny, want to collaborate on an electric power steering? I looked at the splines on the input shaft to the Socket and if a gear was cut to fit those splines with an outer diameter of about 4.5" driven by a .6" X 4.5" gear driven by a .6" sprocket on a 1.31 in-lb 3456 rpm motor. If we create a gear reduction of 57 to 1, we get 1 rev/sec at 6.288 ft-lbs. This assembly could be mounted to the cover cap or even replace the cap or mount it by replacing the input shaft bearing cover with a larger piece of steel that has holes that line up with the socket mounting holes.

Kinarfi

[Guest Lenny]

Lenny, want to collaborate on an electric power steering? I looked at the splines on the input shaft to the Socket and if a gear was cut to fit those splines with an outer diameter of about 4.5" driven by a .6" X 4.5" gear driven by a .6" sprocket on a 1.31 in-lb 3456 rpm motor. If we create a gear reduction of 57 to 1, we get 1 rev/sec at 6.288 ft-lbs. This assembly could be mounted to the cover cap or even replace the cap or mount it by replacing the input shaft bearing cover with a larger piece of steel that has holes that line up with the socket mounting holes.

Kinarfi

kinarfi, sorry I didn't respond to this request sooner. I must have missed it but just ran across it. I'll do a little checking. Stock gears are not that hard to find. I'll get back next week. Leaving tomorrow to go Nellson Hills in Nevada near Boulder. http://www.riderplanet-usa.com/atv/trails/...7/ride_3d5c.htm

Be back sunday torwards evening. Have fox suspension on all 4 corners now and excited to go for a ride. Will do some exploring and suspension tuning evaluation. I'm considering doing a video and sending it to flatbed to hopefully tap into his knowledge base on what he sees. Still going through past post. about 1/2 way done.

Lenny

[Kinarfi]

I would love to design, build, sell and make a fortune with a really neat power steering unit for out Troopers, BUT!!!!! so here are some ideas in case some one want to carry the ball for a while.

First the schematic, two micro switches to drive the 2 3 pole double throw 12 vdc relays, and one single pole 12 vdc safety relay. As you turn the wheel, you activate a micro switch which closes a relay and powers the motor. The thing about a dc motor is that it also generates when turned and the normally closed contacts short the motor out creating a tremendous amount of drag so that if you get a bump steer, first it is resisted by the shorted motor, then trips the switch in the opposite direction. If you lose power, relay C1 opens up to remove the drag caused by the shorted motor. The two relays are interlocked so they can not both turn on at the same time. To activate the micro switches, you need some play in the steering, as I was looking at how to mount the micro switches, I found the shafts that slide together give you enough play.

The second drawing is just an idea of how put the gears on a plate that mounts on the steering box, or we could steal the motor and gear box off our child's Power wheel and build an adapter to tie to the lower half of the steering linkage. Just something to keep us busy.

Kinarfi

[Guest Lenny]

Kinarfi, Thinking about your thoughts on how to do the power steering and just comming back from a Trooper trip, I have developed some concerns. When we drive through a rocky section, the steering is sort of kicked back and forth as we go straight ahead. Also in normal driving we constantly correct our direction. My concern is that each time this happens, the electric motor would want to assist making the steering wheel momentarily kick against or with us slightly. That makes me think about some additional designs that may or may not help. I havn't thought this out extensively but will do so. Maybe others have some input. I'm not a car guy so I don't know all the different ways power steering is accomplished. My thought makes me wonder if a spring, maybe a 2 way torsion spring, on the assist mechanism would stop the feel of the immediate response of the motor. Thus the motors response would be gradually input into the assist. Another thought is that I would rather not have any assist unless I were to turn the steering wheel beyond a certain torque level. I want to feel the road if I may put it that way. When I had my flat tire which was on the front, I felt it as a pull on the steering wheel. I don't want to give that feel up. Along with the spring or on its own without the spring, maybe we could have a rheostat that applied motor power from zero to progressively full power. I'm picturing a torque senser somewhere between the steering wheel and the box. As steering wheel effort increased, the senser sees it an applies more and more voltage to the motor. I can also see a 2 peice shaft coupler in the hookup between the shaft and the motor so we could eaily disengage the motor and gears out of the works thus going back to our current default steering. And finally, When designing machinery, I found that there are an endless variation of 12 volt electric gearmotor combinations available. For example a power seat motor or power window motor, maybe a convertable roof motor. I may still have a catalog of one manufacture, I'll look. With a 2 peice coupler in the works we can go to a worm gear which gets a lot of gearing with only a worm and helical gear and if it quits working, we just disengage it. One thing nice about automotive gearmotors is that they are made by the millions and thus inexpensive and well developed. I'm beginning to beleive you are the most knowledgeable on this forum when it comes to electronics and electrical circuits.

All of us on this forum know that a man of your caliber can easily do this. Oops, I'm using the old con statement to make you feel you now have to do it or your reputation will be lost.

Lenny

[Kinarfi]

Thanks Lenny, just what I need, more pressure Already thought about how to slow response time down on the motor, that would be to an inductor in the line, it resists a change in current, momentarily, then becomes just a piece of wire. Also the speed of the motor can be made to ramp up over time, milliseconds to minutes. Got a project for you, but I need to take and upload some photos for you so I can put the pressure back onto you. I have some parts from a Power Wheels that I can try out to see if this Idea is viable and need an attachment/coupler to test it with.

Kinarfi

[Guest Lenny]

kinarfi, check this site out. go to bottom of page and look at torque, RPMs and cost for one peice. Interesting

http://www.anaheimautomation.com/brush-dc-...gear-motor.aspx

This one is real interesting. don't know cost. will sell one peice at a time.

http://www.automation.com/content/midwest-...lt-dc-gearmotor

Tthis shows what can be found in auto stuff. This won't work but it's $8. If we could just find the right auto gearmotor.

http://www.sciplus.com/singleItem.cfm/term...LogFrom/froogle

anothers

http://www.motioncontrolonline.org/i4a/pag...cfm?pageID=3748

http://skycraftsurplus.com/index.asp?PageA...amp;ProdID=1290

Lenny

[Kinarfi]

Hey everyone, need input, next time you go out driving, see how long it takes to turn your steering wheel from center to lock, trying to figure out how fast of a motor to use in designing an electric assist power steering.

Kinarfi

[Guest Lenny]

Hey everyone, need input, next time you go out driving, see how long it takes to turn your steering wheel from center to lock, trying to figure out how fast of a motor to use in designing an electric assist power steering.

Kinarfi

Kinarfi, ran some numbers today on power steering engineering requirments. Here is what i did. I put a hanging scale in the finger nook in the outter end of the steering wheel spoke. This is aprox. 5.25" from the center of the wheel. With my 31x10.5x15 Mickey Thompson tires at about 7psi, it took 45 pounds of pull to turn the wheel once the tires got past their initial tread flex and finished hooking up. The Trooper was standing still. The Mickey Thompson Baja Claw Radial uses a fairly soft compound so turning them is tougher then a typical tire. Also I was not in 4wd nor locked out and I was on concrete. The 45# at 5.25" gives 236" pounds of torque at the steering shaft.

Then, I sat in the Trooper and pretended I was driving thru a tight curvy trail. I found that about the best I could do reasonably was to turn the steering wheel back and forth through a full 360 degrees each way at about one 360 degree revoloution per 2 seconds. Even though I could probably go faster then this, I pictured myself on the edge of missing a turn if I was going through a tight curvy trail fast enough to require wipping the wheel back and forth that fast. So, this equated to 30 RPM's required at the steering shaft. If your in a turn that is rough enough to make the turning quite hard, 30 RPM's should be enough. If your on a nice wide smoother trail turn and the wheel turns easier, I would assume the electric motor would spin faster with a lighter load. This would give faster steering in those conditions that would realistically allow it.

That said, the Midwest Motion Products planitary gearmotor model #MMP TM55-12V GPk52-046 will develope continuous torque of 46" pounds at the output shaft and 89" pounds peak torque. This is at 100 RPMs and we only need 30 RPMs. If we gear down from the gearmotor output shaft to the steering shaft 3.33 to 1 we get 153" pounds of continuous torque on the steering shaft or 296" pounds of peak torque. I'm assuming that the need for peak torque will always be momentary and thus not continuous. I prefer to see number 25 chain for the final gear reduction. This makes it easy to juggle around with gearing where as gears would be difficult.

Putting this all together, we needed 236' pounds of torque at the steering shaft and the gearmotor will provide up to 296" pounds of torque. Looks pretty good. We also needed 30 RPMs and that is what the gearmotor will give us at the steering shaft with 296" pounds of torque. We know that Midwest Motion Products can modify the chacterristics of the gearmotor to suit different conditions within paremeters. Looks to me like a doable solution for the electric drive and gearing. Add to that switching, an I like what I'm seeing from an engineering standpoint. Of coarse engineering is one thing and the final outcome on something as varied as steering the Trooper in different conditions is potentially another. I would be willing to participate in sharing the cost of doing a prototype buildup. Possibily others would be interested in participating too. The more we have, the less the expirment will cost us. If and when we get one working, we would build enough for all those that participated in the development cost. At the end, each person would have the same cost into their power steering kit. As we know the gear motor runs $322.00 plus shipping for 1 to 5 units. We will have to develope the other cost for a aprox. total cost for each kit. The gearmotor is a good reliable industrial duty and efficient solution for the driver. I'm willing to put $500 into a good working electric system.

Anybody that has input, please speak up. We all miss things and hopefully others can catch them.

Lenny

[Kinarfi]

While I was talking to Randy at Midwest, we talked about backdrive, that's the output shaft driving the motor should power fail and it would add drag, but not that bad, as expected. A cheap method, less than $30 for the motor and gears, would be the use of peg-perego motors, http://tigerimports.net/sunshop/index.php?...t_list&c=14 or Power Wheels motor but the down side is the bulk and it's plastic and it a toy, but costs less than 10%. But it is strong.

[Guest Lenny]

While I was talking to Randy at Midwest, we talked about backdrive, that's the output shaft driving the motor should power fail and it would add drag, but not that bad, as expected. A cheap method, less than $30 for the motor and gears, would be the use of peg-perego motors, http://tigerimports.net/sunshop/index.php?...t_list&c=14 or Power Wheels motor but the down side is the bulk and it's plastic and it a toy, but costs less than 10%. But it is strong.

If we run a chain as the final drive, we can just drop the chain. We could also use a 3 peice shaft coupler with the rubber spider in the mddle. Bearing one side of the coupler to free spin and the other half slides up to enguage it. Then we can just decouple when necessary. This takes the power steering system completely out of the works returning us to stock steering. I may have a couple of the toy gearboxes like your talking about around if I didn't throw them out. I'll check. I can do a torque test to find their failure point. You are right, they are quite strong.

Lenny

[Gumball]

I asked a friend about power steering and here's what he said :

Go to Char Lynn Power Steering. The easiest to install is what they call "Torque Generator", it has a shaft to attach the Steering Wheel to and the out-put shaft to the Steering column. All you need would be a shaft coupler, power Steering Pump with reservoir and maybe a in-line filter. There is a picture of the what you need in their ad.

You might want to call up their website to see what they have been doing.

Gumball

[brostar]

Found info here http://hydraulics.eaton.com/products/steer_main.htm .This model is made for off road and if you read the description, it sounds like what you guys where angling at if you lost power. Char-Lynn® Steering Control Unit Series 10 Dual Displacement

Cheers Mike.

[Kinarfi]

Myself, I'm staying away from Hydraulics. I know and understand electrics. I have 2 toy motor/gearboxes coming and just waiting their arrival. We have a good alternator on our rigs and wiring an electric assist will be the easy part.

[brostar]

T.J's have just released this https://teamjoynerusa.3dcartstores.com/T2T4...-Kit_p_227.html as a stockT2/T4 Trooper Power Steering Kit for MSRP: $1,050.99 I know it's Hydraulic but there you go. The manual to instill is http://www.thunderinc.com/news_releases/op...SteeringKit.pdf

Cheers Mike

[ksimpsy]

if you guys go and read the other power steering thread in this forum about hydraulics you will see a discussion about all the downsides of this type of hydraulic steering system (same as Joyner kit). the main one is that if anything goes wrong with the pump or lines or control box you are SCREWED cant turn. what Kinarfi and Lenny are trying to do here is a electric system that still works manually if something goes ary. I think that if these guys get a system going it would be the way to go for most folks that don't need an extreme system. i will try to get some pics of my hydraulic gear box system up soon for you to see.

Kevin

[Kinarfi]

Thanks for the support! Today I rigged a bar to the motor/gearbox I have and measured the pull at about 12" and got 13 pounds as it stalled, the power supply I was using started at 13.6 volts but dropped to 5.6 and around 25 amps stalled. One more advantage to using bicycle chain and sprockets is that they are easy to change allowing for changing gear ratios so you can dial it in. Also, this is starting to look like an easier setup than I thought at first. The attaching the sprockets to the steering shaft shouldn't be to bad except for centering accurately. Any way, this is starting to get past theory and may be physical soon.

[Guest Lenny]

Kinarfi, thats 156" pounds of torque. Not bad, the Midwest Motion gearmotor has 89" pounds peak. Are you getting enough RPM's. Getting the sprocket centered on the steering shaft is real easy. I feel that the hookup to the steering should be done up at the firewall just above the top u-joint where there is plenty of room. Do you agree with this? Everytime I go back and look at hydraulic, you make the electric look easier and easier. So far you've been a good salesman.

Lenny

[Kinarfi]

the hook up to the steering MUST be below the over lapping part of the steering shaft. The actuating switches are at the overlap and I envision something like a 6" rubber or plastic ball around the switching set up to protect it.

Here's how I see this working, Use the Play between the inner and outer shaft to get our motion sensing by mounting back to back L bracket to the flats, the lower L bracket has an actuator pin on it and the upper L bracket has the switches mounted on it and are actuated by the actuator pin on the lower bracket. The wires from the switches travel up the shaft just short of the U joint and then wrapped around the shaft several times so as the wheel is turned, the wire unwinds or winds up a little more, I saw this on the wiring of an air bag on my boy's Ford. As you turn the wheel, you actuate one or the other switch on the upper shaft, which activates a relay, which powers the motor, which drives the lower lower shaft until it catches up with the upper shaft and deactivates the switch.

What I have learned about the motor/gearbox and how it works: It is built so a L bracket will provide the counter torque, that L bracket needs to be connected to the lower steering shaft, bearinged, and the frame. The output will bolt up nicely to a 4 spoked 4"(aprox.) sprocket and needs a shaft to rotate on of about .434"(that's what was used) and another L bracket to stabilize, this bracket also goes from steering shaft to frame and matches the first L bracket. It looks like the driven/steering sprocket will be most easily attached to the lower part of the steering shaft for room and accessibility and can be mounted to the shaft by using two L brackets clamped with bolts on each side and attached to the sprocket with weld or bolts.

As far as RPM, review this video, notice the black mark, I don't remember what I started out at, 7 or so I think to get 1 RPSec, then turned the voltage up to 13 as the black handle moves. http://entertainment.webshots.com/video/30...t=entertainment we got plenty of speed so we can adjust the voltage to get what we want.

kinarfi

[Kinarfi]

Took some more photos and movies, the drive unit, as I shall call it from now on, can be mounted easily and almost any where above the front diff and below the frame work bars above the diff. The steering sensor need to be up near the fire wall to get enough room to be long enough, this can be done with a tube over the upper part of the steering shaft that is attached to the lower shaft. Check out the pictures and watch the movies.

http://entertainment.webshots.com/video/30...t=entertainment

The movies show the play built into the steering shaft setup and it is that play that can be used to trigger the power unit.

[Kinarfi]

Just spent 2 days with Lenny working on my electric power steering assist and was very impressed with the way Lenny does things. We got my motor/gearbox mounted and connected and powered and did some testing.

SWEET SWEET SWEET

Depending about on your personal preferences, it only needs a little tweaking, and that is mostly electrical. If you're really finicky, It only needs a little tweaking.

I took a bunch of photos during assembly and will take more of the finished version.

Again, Thank you Lenny for the help and for being a wonderful host, and Jeane too.

First of a Series, added more.

Put some protective covers to keep dirt off the chain and off the contacts, waiting to see if anyone spots my mistake.

Drive report: When turning the wheel slowly, it bumps the contact and the motor turns and it comes off contact and stops, then as you continue to turn, it bumps the contact again, motor turns again and comes off contact again. etc. etc. so it turns with a bunch bumps when turning slow, tolerable, but something you'd have understand and get used too, when turning fast, you can definitely tell that it's working, and working good! As you drive down the road and hit the various bumps, the steering wheel stay pretty much where you left it. It doesn't bump steer, and you can turn the wheel when in 4 wheel and locker are in with ease. I'm looking forward to trying it out on a washed out hill we have locally that requires 4 wheel and lockers to see if I have to hang on to the wheel as hard as before. After a test ride with Lenny, the motor was hot and I'm a little concerned about that, need to put some cooling fins on it and maybe cooling fan. We didn't get the end of travel stop switches on yet so when you turn hard, you have be careful not the hold it hard against the stops.

So far, I think we have a good kit in the works.

Kinarfi

[rocmoc]

GREAT! We will get to see the TEST in May. Will you be bringing kits for ALL of us when we arrive in May? How much will the kit cost?

rocmoc n AZ/Mexico/CA

[Guest Lenny]

kinarfi, got an idea for controlling the motor better. Typical electric power steering has built in sensors. One to detect the direction assist is needed and the other detects the amount of torque being applied to the steering wheel. This information is sent to the vehicles computer which evaluates it along with the vehicles speed in some cases to determine the voltage and polarity to send to the assist motor. In your case, you certainly don't want to get involved with the vehicles computer. Consider this idea and let me know what you think.

Lets say we put 15 degrees of slop between the first section of the steering column and the second in each direction. Now picture a bar sticking up out of the top steering shaft portion say 4" in the neutral position. This shaft has a contact on the upper end which slides along a potentiometer connected to the lower shaft portion shaped in an arc. Now below the contact are a pair of springs. One going to the right of the bar stocking up fron the first section and the other to the left. These springs are situated in a manner such that the extended ends make contact with anchors on the lower shaft portion. One to the right one to the left. The inner ends contact the sides of the bar sticking up fron the upper shaft portion. Now as you turn the steering wheel, it starts to compress the spring of the respective direction allowing the contact to begin sliding on the potentiometer coils. The more resistance there is to turning or the faster you turn, the more the contact slides torwards higher voltage. Response can be tweeked by changing spring rates, potentiometer length, coil spacing and /or degrees of slop between the shafts. I think this would eliminate turning with bumps as on a slow turn, the motor would only get low voltage and be slow with you. When the turning gets hard or fast, the voltage ramps up.

Your thoughts.

Lenny

[Gumball]

Hi Lenny,

I must be missing something in the steering setup. How is power to the power assist removed after the turn is initiated? The steering wheel is still turned but no more assistance is needed. Probably the easiest way to state the concern is to assume the steering wheel is turned half way to the left or right. What tells the motor no more assistance is required.

The attached URL shows simple variable resistors (pots) that could be used if you can figure out how to put a neutral in the system. One pot could turn one way and other would turn the other.

http://www.kpsec.freeuk.com/components/vres.htm

Just a thought.

Gumball

[Kinarfi]

Hi Lenny,

I must be missing something in the steering setup. How is power to the power assist removed after the turn is initiated? The steering wheel is still turned but no more assistance is needed. Probably the easiest way to state the concern is to assume the steering wheel is turned half way to the left or right. What tells the motor no more assistance is required.

Gumball

VIDEO http://entertainment.webshots.com/video/30...104110397QxDIyG

There just enough play between the upper and lower steering shafts, as shown by the video, so that the center/upper rod touches one of the other two lower shaft rods and turns on a relay to drive the motor which drive the lower shaft until it moves the lower rod away from the upper, thus stopping the motor.

[Guest Lenny]

kinarfi, It would work the same way as it does now. First the 15 degrees is probably too much but was used to make it easier to visualize. With two pots, and a space in between just like you have now, there is a neutral spot. The assist motor will always run until the neutral spot is reached. There may only be a few degrees of turn required between where the motor is at full assist and quickly ramps back down to neutral and the assist drops off to accordingly. You could also use the existing system start stop rods to pre-empt the pot system. The extra play in the steering shaft could be obtained by inserting a spider type shaft coupler in the shaft. This could replace the springs on each side and the durameter of the center rubber spider would be changeable until the right spring rate is found.

How much currant wil the pots you show handle? I was thinbing of winding our own for an arc shape.

Open for discussion by anyone.

Still having fun with it.

Lenny

[Guest Lenny]

I have another idea. How about using a strain sensor that puts out more voltage the harder it's pushed on. Have one on each side of the center pin. If the strain sensor doesn't put enough voltage, maybe it could be stepped up by a transformer before going to the assist motor. Come on kinarfi, you got me excited so now we have to solove the final problem. The only difference between yours and mine will be a bigger more powerful assist assembly. I feel with the big tires i'm running and the low pressures that a more powerful system will be required. My tires also stick out to the sides quite a bit more adding to the difficulty of turning.

Hopefully your electronic knowledge will fill in the gaps of my ideas. You know a lot more of whats available out there and what type of devise we should be considering then I do for sure.

Lenny

see

www.eettaiwan.com/ARTICLES/2002MAY/PDF/2002MAY09_ICD_AMD_AN359.PDF?SOURCES=DOWNLOAD

[Gumball]

Another part that my be useful. http://www.electronickits.com/kit/complete/motor/k166.htm

Gumball

[Guest Lenny]

Another part that my be useful. http://www.electronickits.com/kit/complete/motor/k166.htm

Gumball

That is real interesting. Thanks for the input. Not really being a electronics guy, I have to drudge through a lot of stuff to figure out how to build something like a pot. On the other hand kinarfi is an electronics guy and it is much easier for him. However this should be interesting to him too.

Lenny

[Kinarfi]

Another part that my be useful. http://www.electronickits.com/kit/complete/motor/k166.htm

Gumball

That is real interesting. Thanks for the input. Not really being a electronics guy, I have to drudge through a lot of stuff to figure out how to build something like a pot. On the other hand kinarfi is an electronics guy and it is much easier for him. However this should be interesting to him too.

Lenny

This one is interesting and as the article states, the FETs are good for 47 amp and I know that this motor can pull 20 or more if stalled. I already downloaded the .PDF so I can study it more. Thanks Gumball.

Kinarfi

[Kinarfi]

Just got back from a trip to Little Sahara sand dunes. I have front rims all around and General Grabber AT2 27x8.50 R14 tires on them. They performed great!!!!!! I also went on trails and roads and I was very happy with them. I was running 10 psi front, 11 psi rear. I had just backed the front shock springs off to where there is only about a 1/4" of thread left showing.

Out in the sand, I found that I could go just about anywhere with no trouble. These were a lot better than the stock tires, but they would probably out do me in the mud, but I hate mud. While out there, I talked to a tire dealer and his comment about my tires was they are as close to BF Goodrichs as they be without them being sued, and BF Goodrich is the most popular tire for the race truck crowd.

My electric power assist worked well also, it resists bump steers so well that you can almost drive hands off and my shoulders didn't hurt like they usually do after the ride. I covered the chain with some sheets of foam to keep the sand out and put some fins on the motor to help shed heat. Because I used relays to short the terminal of the motor when not energized, steering is very stable and because Lenny & I stiffened the the spring in the steering shaft, the amount of force needed to turn my steering wheel is a little more than usual. I'm still very very happy with this design with only a few things to tweak.

Kinarfi