This BBC news published in June 1999 shows that scientist have tried to control the robot through rat's brain signal and succeeded in the experiments.News is old but interesting and therefore i want to share with you.

News says "The scientists trained rats to obtain water from a robotic arm by pressing a small lever. Each rat had electrodes implanted in its brain to record the activity of certain cells." After recording activities, scientist found out the brain cells responsible for this activity.Next step was to capture the signals from brain and to use it to control robot arm (lever).

News later says, "The rats appeared to have little difficulty in controlling the robot arm. Initially, they continued to press the lever, even though this was no longer necessary to cause the robot arm movements.
But eventually many rats learned that they could obtain water through brain activity alone and stopped pressing the lever. "

Interesting!

One More Interesting experiment ""Robo-rat" controlled by brain electrodes" is also described here.