May 19, 201212 yr Looks Great! Now just to add a fifth wheel to it. I have used "2legoornot2lego"'s idea of the quick coupling fifth wheel. Works good but I'm gonna try a new idea so it works more like the real thing. By the way, I tried out your design for steering. The only flaw I noticed is the pin connector are friction pinned, making it hard to steer. I was thinking of using the original steering parts, and cutting 1 in half to use like yours and be frictionless, but I can't see myself cutting Lego pieces. Glenn
May 20, 201212 yr Love the final cab! It really looks awesome for studless. I would recommend 2Lego's hitch as well. It works pretty well and looks good too. tim
May 20, 201212 yr Author Love the final cab! It really looks awesome for studless. I would recommend 2Lego's hitch as well. It works pretty well and looks good too. tim Thanks Tim, It does look good doesn't it the problem with the hitch is that my self steer trailer uses a pin that needs to lock in a fixed position on the tractor unit so it steers the wheels of the trailer so 2Lego's is not suitable. I have spent many hours today making different designs of hitch and have finally come up with a working design that will be able to be hitched by reversing in with no manual intervention and also will be able to be unhitched with out manual help, I hope it works but only time will tell, now to make a prototype trailer to test my hitch design with P.S. I also have to make seats dashboard and steering wheel, I hope you noticed the working 8 cylinder engine in the pictures!
May 21, 201212 yr Author Look's great far better than Timr could ever do. lolz at above ^ Well i did some testing with a rear steer trailer on my hitch system but have hit a problem, my steer trailer uses axles from the hitch to the rear wheels to steer the trailer around the corners, whilst this seems to work okay on a small trailer when i attempt it on a longer trailer it fails, reason been "backlash" to much play in the axels and gears so when back to straight the wheels on trailer are still slightly turned. I am now thinking the trailer needs to be NXTeed with a colour sensor reading a scale on the truck fifth wheel as the trailer turns and turning the wheels accordingly, i will have to do some testing and see what i can do. Its great fun driving round with a trailer though.
May 21, 201212 yr Look's great far better than Timr could ever do. Adapting to studless is hard . tim
May 22, 201212 yr Author Video of truck and trailer prototype in action, ill let the video tell the story
May 22, 201212 yr The truck looks really good! Nice job on the design. I like the hitch. For the trailer, maybe you could try using pushrods that run from the hitch to the rear axle? I'm not sure how well that would work, but might be worth a try.
May 22, 201212 yr For the trailer, maybe you could try using pushrods that run from the hitch to the rear axle? I'm not sure how well that would work, but might be worth a try. I would agree. There is really no way to remove the backlash in the Lego axles . I think beams would probably have less backlash than the axles. Nice looking truck anyway. Could you take more detailed pictures of the hitch? tim
May 22, 201212 yr rodeown... here is an idea for pushrods... i found the idea a long time ago on the web but cant remeber where... i built a mocup to demonstrate... http://www.youtube.com/watch?v=Wl6dNyz0VFs&feature=youtu.be http://www.youtube.com/watch?v=Wl6dNyz0VFs&feature=youtu.be Edited May 22, 201212 yr by gilby
May 22, 201212 yr I like what you have done with the body work. I look forward to seeing the final product.
May 22, 201212 yr Author Steering trailer @ 1:17: Yeah if you look at my earlier vid 3rd post on first page of this thread i have built a working rear steer trailer earlier this year, it worked really well but the axel distance was a short run as in the video you posted, my new trailer is twice as long and as such has twice the backlash of the shorter run so i will have to use a different method. but thanks anyway. rodeown... here is an idea for pushrods... i found the idea a long time ago on the web but cant remeber where... i built a mocup to demonstrate... Hey Gilby, Thank you for taking the time to do this, after pushrods were mentioned i did my own small test but realised that it wont work because a trucks trailer can turn more than 90 degrees in some situations so the push rods would come to the limit very quickly, not sure how to get around that because a clutch in it would cause problems as the trailer would go out of sync with the tractor unit. I am trying to get my head around the NXT sensors and motors at the moment i have few ideas but will test them first.
May 22, 201212 yr Love the finished design of your truck Rodeown. Look forward to seeing the finished trailer.
May 23, 201212 yr Author Love the finished design of your truck Rodeown. Thanks TimH, Okay Lego NXT experts i need some assistance, I want to use motor A as a rotation sensor so that Motor B matches it exactly, I have spent many hours trying to work outhow to do this but not found any answers yet, the closest i have come to finding a soloution is in the video below at the 8.00 minute mark but that would entail the purchase of a Hi-Technic angle sensor, I am sure it can be done with a normal NXT motor used as a rotation sensor as they output the degrees of angle -/+ as they turn i just cant work out how to transfer the position of A to B anyone got any ideas? Could you take more detailed pictures of the hitch? tim Here you go Tim, hope its okay i will do a small video as well with the hitch off the truck so you can see the underside of it. video finished now Edited May 23, 201212 yr by Rodeown
May 23, 201212 yr Why do you not just have a pf motor in the trailer and then use a extension cable to the battery box from the motor?
May 23, 201212 yr Author Why do you not just have a pf motor in the trailer and then use a extension cable to the battery box from the motor? Alasdair, the problem isnt about what motor to use in the trailer but about how to sense the trailer is turning and how far it has turned so the motor at the rear could adjust the rear steer accordingly. Anyone could make a rear steer that requires input from the user on a controller, what I am attempting here is unattended rear steer that is progressive and works correctly. Someone suggested linking it to the front steering but that wont work because there are so many occasions when the truck is steering opposite to what you need the trailer to steer. I am confident that I/we will find a soloution, I am not someone who gives up on a problem.
May 23, 201212 yr Author Ok what about adding gearing down/up in the trailer so the trailer steers more? Yeah maybe,trouble with more gears = more backlash which i am trying to get rid of IE reason for NXT use, but if i get the NXT idea working then i can set the amount of steer at each stage of the turn to what is appropiate so for example i could take the output from the rotation sensor and increase it in a math block through lets say 20 to 60 degrees then back to normal through the rest, this would open many options for the control of the trailer, maybe even an nxt switch on the truck that triggers during reverse to provide a reversing siren "backing up Backin Up" I could also add a switch for the trailer tipping aswell maybe! Yeay i Love lego! STOP THE PRESS. edit just managed to get the rotation to transfer to the other motor. (corrected the sound issue i had on this video.) Edited May 31, 201212 yr by Rodeown
May 24, 201212 yr Author well after extensive testing on the trailer using the nxt motor as a rotation sensor i have found a problem, the motor, whilst it can be turned freely by hand it suffers from a "cogging" effect so when connected via a pin to the tractor unit it turns in steps rather than smoothly (probably why hitechnic designed a non resistance angle sensor) so to steer the trailer via this method i will need to buy an angle sensor. Moving on, the colour sensor might be a better option because then i am not relying on a tight held hitch connection and the colour seen under the sensor will instruct the nxt brick to move the steer motor accordingly, so back to the drawing board for more testing.
May 24, 201212 yr rodeown... regarding my video... i see what you mean by the limitations... to counter that i replaced the beams in one area with rubber bands which still steer the trailer but at max steer it still allows the hitch to turn without pulling the trailer with it...
May 25, 201212 yr Author rodeown... regarding my video... i see what you mean by the limitations... to counter that i replaced the beams in one area with rubber bands which still steer the trailer but at max steer it still allows the hitch to turn without pulling the trailer with it... That is a good option, I am thinking to put my steer trailer on hold for a while and get back to it when i can get my head around it some more, I did come across a company called Mindsensors that make some interesting sensors for Lego NXT mindstorms, they are developing an angle rotation sensor at present and it would be perfect for my trailer use but i have to wait till they go into production, here is the link to them anyway Mindsensors upcoming angle sensor
May 27, 201212 yr Well, if you wait a couple months, maybe the use of the servo motor would work with the switch. It would be full steer on the trailer when the truck is turning, but have return to center when the trailer is straight.
June 1, 201212 yr I just watched your latest video. If you can't get a mechanical linkage to work, a solution simpler than the NXT might be to link two s together.
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