Not a lot of detail is given about the geared motors on this chassis, and the pictures do not even show wires connected.
My specific questions about the motor:
]Are they brushed or brushless?/:m]
]What additional hardware is necessary to take advantage of the “Encoder Discs”? /:m]
]A pointer to full specifications./:m]
Hi,
Here are answers to your questions and comments about the RB-Elf-42 platform:
Indeed, there is very little information about this low-cost kit. All the information available on the product page is what is currently available from the manufacturer. You would most likely have to solder your own wires to the motor connection points (2 per motor).
The kit uses 2 small geared-down (1:48, no details on motor RPM) brushed motors (see specifications for more details). Please note that the lack of detailed specifications is one of the reasons why they are to inexpensive.
Typically, these type of wheel encoders are paired with an optical sensor, such as the one used in the RB-Cyt-39 kit. You can find some options here. For example, the RB-See-190 has a rise/fall time of ~ 5 µs (datasheet, page 3). Therefore, it can switch at a frequency of at most 200 kHz, which should be sufficient for your motor. Assuming a RPM of 230 (see below) and encoder wheels that seem to have 8 bars per rotation, it would at most cause 230 x 8 = 1840 signal changes (from high to low (fall) and low to high (rise)) per second or 1.84 kHz.
To use such a sensor, you will need to detect the pulses (either the “highs” or the “lows”, basically the transitions). You can read this post for details about ways to do this. There is also this long article on Arduino about how to work with rotary encoders of many kinds, including those that only product a rotational count (certain amount of pulses / revolution). You can view it here. It presents many approaches, from using the main loop to interrupt driver (optimal if the code does anything else).
There are no full specifications available for these motors at this time. As mentioned above, they are commodity hardware that is very inexpensive. Part of the reason is that they are not fully tested or spec at manufacturing. Therefore, it may be possible to obtain rough values for them through testing, but those are not usually provided by the supplier or manufacturer for this kind of product. We have contacted the manufacturer just in case and we will post here again when we receive a reply from them concerning this.
From what we can gather online at this time, they are typically rated for 6 V DC and have a rated current of ~240 mA. The RPM would most likely be around 230 with a torque of 0.8 kgf-cm (not details on if this is rated torque or stall torque). Please note these specifications are taken from similar (but maybe different) motors, so they may not apply to it seems very likely they would have very similar specifications.
We hope this information helps!
Sincerely,
Thank you, that is about what I expected. The part I am wondering about is how to mount the encoder boards in the small space below the chassis. I may have to go to a larger custom chassis eventually, but this should get me started.
Hey,
Here is what the manufacturer said about the motors:
We have informed our web content team and the product page for RB-Elf-42 should be updated shortly.
Concerning the mounting of the encoder, maybe the manufacturer will have ideas! We are asking them and we’ll see what they think about this. 
Sincerely,
