Motion sensored object avoiding robot

Hello,

I am making a robot that runs away when something comes near to it. So far it has two ultrasonic sensors on it to avoid objects. I would like these ultrasonic sensors to be activated by a motion sensor when someone comes near to it.

It is for a dog toy, essentially, the dog can chase the toy and as the robot moves it uses the ultrasonic sensors to avoid crashing into things.

The robot is set on a chassis with two wheels, a castor wheel, two stepper motors.

Also I would like to add a switch or a remote control function to turn it on/off.

Thank you in advanced!

Sounds like a fun project. I see no question so I asume the project runs according to plan. Can You show us the present status of the toy?

micballas:
The robot is set on a chassis with two wheels, a castor wheel, two stepper motors.

You sure that are not regular brushed DC motors? The ones I have with an identically looking kit are way too cheap for being steppers, and have only two connecting wires... Steppers don't make sense in this application anyway.