G+_Eddie Foy Posted December 28, 2015 Share Posted December 28, 2015 Looking to make a RC car/bot. But I want it slow walking speed (max 2x walking speed) As a base for a robotics platform. Ideas? I grabbed a $10 WalyWorld RC to to play with. All the RC cars and such I see are looking to go as fast as possible. The tanks are probably slower but not what I'm looking for. Link to comment Share on other sites More sharing options...
G+_Jason Marsh Posted December 28, 2015 Share Posted December 28, 2015 RYO, then you can give it the capabilities you want. Or, go back in KH history and build the lunchbox. Link to comment Share on other sites More sharing options...
G+_610GARAGE Posted December 28, 2015 Share Posted December 28, 2015 This may be a little too slow (if memory serves, a little slower than walking speed), and it is not an rc car, and is kind of pricey for what you get, but it does make a good robot platform. You can replace the tracks with wheels if you want, but it is skid steer. https://www.sparkfun.com/products/10336 Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted December 28, 2015 Author Share Posted December 28, 2015 Thanks guys! I've looked at all of those, along with others from ServoCity, Polu etc. But some of the caveats are: brush-less vs brushed. Gearbox input speed if using brush-less motors. The Lunchbox build is the typical go-fast car. Have a feeling I'll be doing a full DIY. Grab a couple of PICs (sorry, not an Arduino fan boy) and H-Bridges and rolling my own controller. Link to comment Share on other sites More sharing options...
G+_Carlton Dodd Posted December 28, 2015 Share Posted December 28, 2015 Couldn't you build one with a reasonable brushless motor, then limit the speed in firmware? This would seem a more flexible solution. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted December 28, 2015 Author Share Posted December 28, 2015 Carlton Dodd Not really. DC/AC motors develop max torque at rated/highigh speed. By lowering the base speed, you are starving the craft of power thus reducing the efficiency and usability. Stepper motors on the other hand have max torque at lower speeds. Link to comment Share on other sites More sharing options...
G+_610GARAGE Posted December 28, 2015 Share Posted December 28, 2015 Wayne Hobbins Whatever you do, do not share that link. :) Link to comment Share on other sites More sharing options...
G+_Black Merc Posted December 28, 2015 Share Posted December 28, 2015 I thought brushless as on quads where basicly stepper motors... the speed controller controls the speed and leaves torque to the current the motor requires. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted December 28, 2015 Author Share Posted December 28, 2015 No the quad motors are FAR from steppers. They are triple phase AC motors. They vary the freq to change the speed. Link to comment Share on other sites More sharing options...
G+_Carlton Dodd Posted December 28, 2015 Share Posted December 28, 2015 Brushless + gearbox? ? Link to comment Share on other sites More sharing options...
G+_Black Merc Posted December 28, 2015 Share Posted December 28, 2015 Still! Brushless motor... argue definitions later.? frequency change applies to stepper as well. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted December 29, 2015 Author Share Posted December 29, 2015 Why brushless? What make them any better? Steppers don't actually work from freq, but sequential voltage on the leads. Apply a constant voltage, and it locks up. Link to comment Share on other sites More sharing options...
G+_610GARAGE Posted December 29, 2015 Share Posted December 29, 2015 Eddie Foy My gut says go brushed. I hesitate to say this because I don't know if it is true, but my gut says that a brushed motor will give you more torque during stall condition than 3 phase motors. I think this is true because in a brushed motor, your magnetic field is always placed in optimal location. In a 3 phase motor, your stator has to chase the rotating magnetic field. However, 3 phase motors are probably more compact, simpler (aka more robust) and won't produce as horrific emi compared to the brushed counterparts. But at the size you're talking about, emi probably won't be a big deal. Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted December 29, 2015 Author Share Posted December 29, 2015 And brushed are MUCH easier to do speed control on. Simple H Bridge with a PWM and directional signal. (and a little filtering/buffering to reduce noise. Trip phase does create noise when it has speed control. All industrial freq drives use shielded cables on the output side. Link to comment Share on other sites More sharing options...
Recommended Posts