Monday, May 15, 2017

Additions to the assembly guide

There is a detailed assembly guide on the project page (also in Hungarian). There were some questions, however, that I found better to address in this blog area.

First the assembly style. The assembly guide just states that electronic boards, etc. should just be attached to the chassis. How you do it is a style question. For example the robot that my son assembled sports a low profile.

My version is less elegant and also less stable mechanically as the boards are all stacked onto the back of the chassis.

I have a good reason for clearing up the front part of the robot - I am already preparing for the next steps when additional embedded computer (or computers) will be added to provide higher-level functions like image processing. The front part is ready to accept those cards.

Next, about the battery. Arduino Uno's recommended input voltage range is 7-12V. So you need at least a 7V battery pack. My solution is a 2-pack Li-Ion battery pack as shown in the image below.

This should not be an issue, however. Use whatever battery you have at hand provided that its voltage is in the 7-12V range. Be advised, however, that 4x1.2V NiMh batteries that fit into the battery holder that usually come with these robot kits will not provide enough voltage. If you stick to 1.2V AA batteries (rechargeable batteries frequently found in supermarkets), you need at least 6 of those. If you follow my advice and go for a type 14500 Li-Ion battery, don't forget to obtain also a charger. Even though type 14500 comes in AA form factor, ordinary AA chargers designed for the 1.2V NiMh batteries will not charge them.

Also, be careful that you can damage the Li-Ion battery by discharging them below the safe voltage. This is not a serious issue for our robot because the motors will stop functioning long before the batteries are discharged below the safe voltage. But if you leave the robot stuck somewhere with the batteries turned on, you can get to this situation.

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