The problem with the NYPD robot is design. It's goofy as fuck. You want to make a police robot effective, you make it intimidating.
All you have to do is take a few off the shelf quad-coptor drones. Mount them high in the corners so they have full view of the area. Perched like falcons. Then every once in a while they take off, flash some lights and blow a siren and fly around for a minute. Then, if you really wanted to, you could incorporate some AI that would recognize and report a crime.