PKW

Eurobricks Citizen
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About PKW

  • Birthday July 10

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  1. At this point using nxt and ultrasonic sensor why shouldn't be accurate? Also in place of a torch, that diffuse a lot of light, there can be a laser maybe with the help of some nebulizer there will be also a nice effect
  2. Waiting for a video too! Looks really cool and with great offroad capabilities If you click on the images they redirect to the page. But yes stricekfido maybe adding a link could be the right thing ;)
  3. thanks for sharing! it is a good think lego implemented a difference like it did for v2 receiver having cable bending protection on connectors
  4. i love the idea of the race and a sort of fast like competition like the indoor car race or the lego technic rally, what about allowing cabled cars with 3rd part wires? also, how can i recognize if a battery pack is "new" or not without stressing it?
  5. i agre with what is there, and yes my mechanism lead to a permanent differential "work" but the results is that torque is not distributed equally to both axles and so you have "kind of more torque" to the front one, this is why it slips and the other stall because the dill gives more torque to that one. and off course the effect has to do with friction, how can we easily measure torque if not putting it agains an equal friction and see what "win it" more easily? also i don't know where that mechanism would be used, but i have to agree that is is not suitable for high speeds but for a supercar model or some small rc veichle it should be ok, even for a torque distribution on a drifting car
  6. wonderful, i really like the only half stud offset from the two sides, generally i don't like that offset but is almost impossible to have other efficient solution at that scale, also you've made a really good work with the steering!
  7. the point is that the differential is there to avoid different speed, also, we won't have more toque than the input at front but just more torque than the rear axle, in this cases the "limited slip" is the friction of the non geared axle to the ground (trough wheels), because as long as it doesn't slips the mechanism tend to give torque to the other wheel, this would give more speed to it but the differential and the fact that both wheels are mounted to the same chassis (so inserting a difference in speed will increase toque required for the faster wheel) prevent this. i hope i can make a super small video to convince you here is it, you can notice that only the geared down wheel slip (more torque) but the car move in a straight line that is the average of the speed of the two wheels (so actually a 1.5:1 ratio is applied to the output of the diff)
  8. Sorry for the late reply, there are two options to compare our solutions: if with your solution both motors will be connected together, the we will have a sort of electronic differential, so current may flow more in one motor than in the other (this is not correct but it is a easy-way explanation) so the speed of the two motor will "more or less" balance to the same, and will be helped by the gear ratio. however if the two motors are, for example, powered by different receivers on different batteries then each motor will try to force the other to go at the same speed, with a significant loss of power in my suggestion (that was also the first idea of tomek) the central diff will always balance speed by acting on modifying the amount of torque on the rear axle, in the same way that does when you have a central diff and the front axle is on a slippy surface while the rear one no: it will give more speed to the front one and more torque to the rear one (but since the toque on the rear one is forced to be equal to the resistance on the front axle you car won't move). http://www.brickshelf.com/gallery/PKW/MISC/schermata_2017-05-27_alle_13.27.01.png so let's examine the mechanism up here: the differential would give all the speed to the 3:1 geared axle, but doing that the axle would be braked by the other one, so it moves from having 1/3 of the fricion to have the same friction but requires 1/3 of the torque to balance it, at this point is t clear than the 2 axles will move on the same speed but with different relative torque, until the external friction will become too low to keep the geared down axle to slip, at this point we return to the start position where all the speed will be given to the geared down axle, more over it is important to say that with friction x to the ground you need to have less than 3 times the friction on the rear axle to make it slip, but only less than the rear axle friction to the front one to make it slips
  9. yes: you need this setup: a differential chase moved by your main motor, and the two differential output A and B (not connected between them so they can rotate independently) one for front one for rear, what you'll get will be that you need same torque one the same output "of the differential" this means that if you gear down A by 1:3 ratio, the other will have 3 time less torque than the first, but mind that the sum of both toque will be equal to the main motor torque minus the amount taken by friction, and since it is a differential both output will tend to rotate at the same speed (when they have same friction, so like 4 wheel on the ground need to move 1/4 of car weight each) in a low friction condition the geared down part will slip "3 times easier than the other" because it actually have more torque. But remember this is not really torque vectoring but only torque distribution (if i'm correct)
  10. i know it was me to suggest that, unfortunatelly i bought and return several economic joystick that didn't worked well, but what i noticed (with ps3 controller trough otg) is that "skid steering" is not proportional so while moving slowly even a small tilt of the joystick on the left/right result in a turn, there is no way to make it feel like a real controller? this is what i use on my arduino, note that left/right/front/back are pwm signals [0;255] each one corresponding to one direction of the joystick, i don't know if this can be useful, maybe you can add a toggle for joystick that say "skid steer" and then "select left track...select right track" and it set everything for the control by itself if(back < 0) //cottect the turning direction while go backward but not while pivot turning { sentData.speedmotorLeft = back -right + left; sentData.speedmotorRight = back + right - left; } else if(forward >= 0) // else could be called but else if prevent some strange moving if forward is negative due to wrong initialization { sentData.speedmotorLeft = forward + right -left; sentData.speedmotorRight = forward - right + left; } //recorrect the data not to have more than while 255PWM while non pivot-steering sentData.speedmotorLeft = constrain(sentData.speedmotorLeft,-PWMmax,PWMmax); sentData.speedmotorRight = constrain(sentData.speedmotorRight,-PWMmax,PWMmax); NB2: you don't need the else, that is there to make the tank turn like a car while going backwards
  11. JOINTS all technic moccers knows that lego u-joints are fragile and sometimes difficult to use, are you planning something more robust or with more degrees of freedom? will see a new wheel hub with those or the actual form will be leading production for years? CONNECTORS we all love the 2 female cross hole connector but when we need non standard axle lengths (like 4,5 or 10,8 studs) for axles connecting each other in a diagonal way and not in a straight line is really difficult to achieve a good result, more over there is no "extensible axle" that will fit sliding mechanism that vary distances between axle and lego builders invented a lot of solution like this but we will ever see a TLG approved solution aka a new part? this could be an IDEA jim feel free to edit/rewrite my question, i'm not too got at explaining myself in english
  12. Wow really cool, what will you use to "pick" objects? Some sort of pincers or a lego suction cup?
  13. But remember you are 3rd of IR category! And more over you were first for the first 15-20 votes, planning on making a better graph that shows how votes evolved for the first 6 entries but quite difficult with my actual knowledge
  14. thanks you all for the votes! but most important congratulation to all the other contestants for the great entries i've seen in this contest! i was running a program to calculate scores and i can confirm the results (but i was sure there will be no error here!) i made a couple of graphs that i hope you like: in this one you can find the name of the entry and (from the bottom to the top) how much 1s,2s,3s,4s,6s,10s they received on the contest with a dot that is larger more votes the entry has taken in the second there is a spimple graph with names and scores so you can understand better how is the point distribution, some names are overlapping but i think they are readable, sorry for the inconvenience
  15. due to building lego combat robots i decided to vote by taste! and i think i found some of the best overall, also a mention to blackout for good srimech and look to thumper for look and to la grange 3001 for unique design! good luck to everyone 9:10 15:6 21:4 30:3 18:2 7:1 10 to bison due to packing 4 functions in a invertible chassis with only 2 motors 6 to maximum impact due to the effective internal compactness and chassis strength of the best of "big bots" 4 to the blacksmith for compactness and strength, one of the most difficult bot to defeat! PS have to admit that i would've placed my bot 2nd in this scoreboard but i think the lack of a proper srimech from other good bot can make it able to take the lead (in my mind)