Good home and business security starts at its perimeter. But typical security is all boring boxes and fixed, or it's biological and messy --read employee or live animal. And so my idea for a robot would be to have an animalistic one that prowled the yard.
It could 'poop' mini cameras in specific and pre-determined spots and even retrieve them at a set or commanded time. A dog shape or a duck shape would be great choices. My favourite one is the duck. The wings could act as self righting mechs and also flapp vigorously when an intruder appears. Its mobility being easily afforded with sensor filled webbed feet. Night vision cameras for eyes that could extend and swivel would make it an evil enough looking creature and provide 360 degree vision. Its wings when open or closed, can broadcast text messages and from its mighty beak can roar whatever sounds its operator chooses. Alarm bells, a siren, a really loud duck shriek, a 'you are on private property' message, whatever you want.
And it can chase the intruder intimately.
A totally water-proof robot that I would call a 'robani'. A mix of robot with animal behaviours that sends real-time data back to you. The robani's own back-up security is all of its poop cameras already pooped. If one goes down there are others, and robani can always drop more. It's a visually responsive and mobile security that can actively pursue intruders, increasing the fright level. Spring actuated knee joints and feet claws would make this beast something an intruder would not want to be near. All robani's would also have a clear gaseous stinker out-let that blew vomitable fumes towards the bad person.
For in-house check option, it could enter a property via a cat-flap or similar, and follow a basic line-strip. A re-charging station at the back door where it takes itself when its batteries are low. Whilst on recharge, it's still transmitting but at a slower frame rate. Any attacks on the robani itself, are recorded by the poop near-by and the stations own monitoring eye.
Another good animal choice would be a robotic grass snake.