New Delhi, Nov. 18 -- Robot vacuums promise fuss-free cleaning. You press a button, and let the machine glide across the floors of your house on its own. But after a few uses, many users are now facing an annoying problem. Instead of moving in straight lines, some robot vacuums begin spinning in circles or wandering in odd zigzag patterns. It can look like a major failure, but most of the time, the fix is simple and does not involve buying a new device. Here's what the experts say might be the cause of this odd behaviour.

A very common cause is a problem with the wheels. Each wheel has a small sensor that measures how far it has turned. If dust, hair, or dirt gets inside this area, the robot may assume a wheel is stuck. This makes it kee...