12V SLA Battery Charge Controller
"...what device should I use to charge the battery when this is connected to the robot circuit and at the same time regulate the output to 12V?"

Any 12V SLA battery charger would work, however,  I would recommend you ensure you have voltage protection between your charger &amp; your robot.  Charging voltages can exceed 14V and your 12V robot regulator circuit will need to handle that extra V or be isolated from the charge V during charging--if you prefer to protect it that way.

Personally, I think you'd do better using a li-ion battery as it has a higher energy density &amp; it weighs much less than lead.

hth!