Hey guys, I went to school for electronics engineering but have been out of school for a while. Looking for a fun project. I was looking to build a robot for fun. Something that can drive around my house with a small camera. I would use my laptop to control it and have a live streaming camera so I can see as I drive. Im thinking wifi based robot. With some sort of arm to grab some stuff off a shelf. So it would need to carry a couple pounds. I havent really done anything like this before and my programming is pretty minimal. I have an arduino uno. I need some advice selecting the rest. Motors/controllers and how to power them properly. I would like to make the framing myself I have a shop so I can pretty much fab anything I can think of. Id love to start with use a base I can drive around with my laptop then work on adding onto it from there. Trying to keep this a fairly cheap project to.
This is why I am on this forum, and so far it is awesome. So from what you tell me the CIM seems like a poor option for me. Is there something you can better recommend. I am having a hard time trying to remember my physics. A motor at say 343in oz in stall and 5300 rpm, generally makes half oz in power in mid rpm Correct? Now how much weight can it move driving wheels. Ive been looking through math and forumlas and stuff. Im just trying to find a general rule of thumb, I dont need exact measurments, 5 mph would be nice. 2-3 would be ok, weight will depend on what I add to it. Depending on battery probably 50 lbs to start.
a 4" wheel would have roughly 12.5 " travel per Rev. Based on the cim motor operating had half power at 2650 rpm it would be travelling at 30mph lol. I would need 10:1 reduction. Guess I should have done my math first.
Thanks again, You are so helpful. I think I am going to go with the 185$ kit with the two xbees. I believe that will work for trying to control it from my laptop. Will be a great leaning experience!
Welcome to robotics! Take a look at the following tutorial which can be of help: robotshop.com/blog/en/how-to-make-a-robot-lesson-1-3707
The base you create will need to be large and heavy enough to carry a robotic arm and a payload at a distance.
Not too many arms can reach 1.5m off the ground to pick up objects from a shelf, but it can certainly be done.
The motor would be the most important, as it needs to support the weight of the chassis, electronics, battery and arm. Once you have chosen the motor, you usually have a selection of motor controllers you can choose from. We suggest starting with a two wheel drive system with rear caster; this means you only need two gear motors and one dual motor controller. The frame itself does not need to be complicated (as simple as a piece of wood if you’d like).
The issue with the CIM motor is that it needs to be geared down, and the gearing is usually several times more expensive than the motors (there are many gear boxes made for the CIM, RB-And-39 is just one). The other issue is that they consume a LOT of current when in operation, meaning you need a pretty powerful controller (50A+ continuous), and batteries which can provide ~100A continuously. A good controller in this range is the Sabertooth 2x60A. The VEX Victor and Jaguar are not ideal for a standard CIM motor.
As for the caster wheel, you just need something which can support enough weight. Using two or one is a matter of preference, but you may find that using two adds a bit of stability. Usually you don’t need four casters.
For a battery, you need something pretty powerful, capable of providing 100A continuously. That would be either a lead acid battery (heavy), a large NiMh pack or a really expensive LiPo. Currently we don’t have anything ideal for the CIM motor.
The big issue is that the heavier you want the robot, the more you will need to spend on the motors, controller and battery. If you are new to robotics, you might consider investing a little in a smaller kit which you can use to learn, for example the DFRobotShop Rover. The tools on GoRobotics will help with the calculations.
We’d suggest a WiFi module such as the WiBi Bee 2.0. The shield may work, but you always need to check which pins are used. Usually a AA battery is about 2Ah, so a 6Ah should (roughly) last 3x longer. The main difference is that a 3.7V LiPo causes the motors to move a bit slower than 4xAA = 4.8V / 6V.
If you opt for the WiFi bee, you’ll either need two XBee headers (and the ability to solder them to the board) or an IO shield. If you opt for AA batteries, be sure to remove the LiPo jumper at the left rear of the board.
Sounds good. That will give you enough experience creating a mobile robot. We would also suggest purchasing a small pan/tilt kit to learn how to control servos. If oyu want to add sensors for obstacle detection, you can get experience using those with the Rover as well.
