I am not a current owner of Zumos or similar Pololu beasts, but I'll probably soon be.
My opinion on the Zumo 32U4 robot is that it is a really nice device,
equipped with plenty of sensors. Its only drawback, at least for my own purposes,
is the difficulty in expanding it with other peripherals/sensors.
For example, I'd like to put on it an ultrasound sensor, rotated by a servo, and scan the room
by sonar measurements to obtain a rough map by some kind of poor-man's SLAM.
Unfortunately, expanding the robot does not look easy, because the system is quite closed, with no free pins.
Adding anything, means cutting and soldering.
As my idea is to use a set of robots for didactics, with 18-year-old students, I'd like some more plug-n-play solution.
Anyway, here is the scenario I imagine:
1. buying a group of 32U4 robots, then modifying some of them by...
2. soldering four wires for I2C connection and power sinking, then...
3. somehow mounting an arduino (or a better card) on the top of the robot, connecting the 32U4 and the arduino by I2C and power supply, finally...
4. using the arduino for expansion and additional computational power.
In this way I could connect anything I like (reasonably, in terms of weight and current consumption) which would be very interesting from a didactic point of view. I can imagine wireless communication between modified Zumos or between a Zumo and a pc, and other applications.
I'd like to know what Zumos users and creators think about it:
* would it be mechanically possible / impossible, easy/difficult to mount an arduino card on top of a Zumo?
* is it easy to solder on the SDA/SCL pins and on a couple of Vcc/ground pins?
* anything I am not thinking of?
Before closing, I wish to warmly thank Natham Bryan from Pololu for patiently and exhaustively answering my first questions on the subject, directly addressed to him.
p.s. This message was ready to go this morning, when jan187's question "Zumo 32u4 high speed connection to Raspberry Pi" was not in the forum yet: I've seen now his question, which is somehow similar to mine (interfacing between the robot and an external processor).