>Hey /diy/, I am trying to build a robot that will follow me around autonomously, think R2D2 and the like. I'm thinking of using bluetooth as an interface and using my smartphone as the transmitter. A few questions: would it be possible to do this without having to use GPS? How would I go about a wireless system of logging distance and direction of movement between the two objects (the robot and the transmitter, ie my phone)? Any thoughts at all would be helpful as I'm only in the beginning phase of this project.
>Pic vaguely related
>>918456
You should describe the scope of the project some more. Is this robot supposed to do pathing and obstacle avoidance so it can navigate to you from the other side of a building, or just drive towards you in a straight line when you're in the same open room?
I don't think bluetooth is the right technology for this. It's a pretty complicated protocol so you're going to be limited to using microcontrollers with bluetooth transciever hardware and other people's bluetooth stacks because doing all that from scratch is 1000+ skilled man hours of work. Bluetooth stacks and hardware aren't designed for your application; most won't tell you the signal strength, and none of them will tell you the angle from the robot to the smartphone because that requires putting the bluetooth antenna in a small dish and waving it around, which isn't how bluetooth was ever intended to be used.
Two options I'm thinking of:
Use dead reckoning from your smarthpone's accelerometer/gyroscope to get it's position. Use that as breadcrumbs for the robot to follow. Send position data over wifi or bluetooth.
Put a simple radio carrier transmitter, IR LEDs, or any other sort of beacon on your leg and directional sensors for it on the robot.
>Robo-ducklings
GPS and a two-way radio datalink is probably the most straightforward approach, but I'm wondering if acoustic homing might be conducive to favorable behavior (i.e. robot follows sound of a beacon as it reflects and diffracts around corners and such).
>>918456
Op there are some Bluetooth homing devices out there you can look at
Even a few Arduino projects for car and cat tracking etc.
Once you know where it is its easy to follow it.
>>918485
>>918478
OP here, sorry I wasn't very clear. Roboducklings is essentially the idea. I want it to track and follow my movements and go around a bend after I go around a bend. The reason I had been thinking bluetooth was because it would never be farther away from me than say 5 feet and would stop about 2 feet behind me when I stopped. Thanks for the responses, I appreciate it a lot. Eventually I want to get it to be able to recognise obstacles and follow me onto escalators and stuff but that's waaaay in the future. For now I'm just trying to get an idea of how the hell it would track me in the first place. I don't want to get into the whole obstacle recognition clusterfuck quite just yet if you know what I mean.
>>918456
Bluetooth tracking lacks the fidelity you're looking for... it's more for "I'm in this room" than "follow me". True wireless position trackers require highly synchronized clocks (which Bluetooth does not support). It's not really a /diy/ circuit because the frequencies that are too high to breadboard (trace lengths and shielding impact the signal).
Ultrasonic positioning is more /diy/ friendly, but requires a wide baseline distance between the microphones - whether you can use ultrasound will depend on the size of your robot and the distance you want it to follow.
Optical would be the easiest, but it's not robust in outdoor sunlight (there's a lot of IR in sunlight). Think Wii controller. In fact, you could use a Wii controller! It provides enough information to calculate distance and angular position, it communicates over Bluetooth, and the protocol has been reverse engineered. You can build your own Wii-style tracker: You'll need a camera. Replace the lens (the IR-cut filter is usually a coating) with a clear lens and IR-pass filter (looks like opaque black). Set the camera to manual exposure and tune it so everything is near-black except the IR LEDs. Capture the image, apply a threshold, and find the center of each bright dot.
>>918456
do they make Wankel engines in the form of bearings the make the main outer structure of a ducted fan jet pack with a after burner from venting the air/fuel/exhaust gasses through the air movement area yet?
>>918847
if the combustion carries over to the airfuel exhaust area for a second combustion and vents into the air output and builds rpm. and maybe a ignition control. would it be lightweight? if it drips fire its ok.
Build a ROS turtlebot:
http://www.transistor.io/homebuilt-turtlebot.html
Then use the ROS' s AR tag tracking packages to rig something up that looks for an AR tag that you wear
