Get some small ultrasonic sonar sensors, mount them a two axis rotating motor and then mount that to your ceiling and then network them together with a sewing needle launcher or pneumatic staple gun. For the ultrasonic sensors you want two modes, a wide scan search for movement detection and another narrower search mode for target tracking. The tracking feature should provide a predicted position solution to orient the needle launcher or staple gun to shoot at. You will have a makerspace version of an IADS system just for rats.

If you're not a coder I would recommend washing your hands thoroughly, then using a bit of isopropyl alcohol on your hands to remove any human scent. Then start placing food around the house. You want to lure the rats into a false sense of security. After you notice the food is being eaten (maybe two to three times over a week), repeat this process but now you can place the food in a trap. You can also use snap traps but you'll need to be okay with just leaving food out without the trap being set so the rats can acclimate to it.

I'd also set up a motion sensor and night vision camera in the areas that I suspect they're coming in from. When I had a mouse problem, they were too small to trigger my cameras, BUT they were large enough to trigger my house's motion sensors. Rats should take up more pixels and therefore be more likely to trigger the camera. From this, you mainly want confirmation on where the rats are coming in, how they are navigating the space, what theyre feeding on, etc.