Velocity Feedback Control System for a Rotor of a Toy Helicopter

Abstract

There is provided a method and apparatus for controlling a toy helicopter in flight. The toy helicopter is powered by a first rotor and a second rotor. A target speed ratio is determined for the speed of the first rotor and the speed of the second rotor. The speed of the rotors is adjusted incrementally until the target ratio is achieved

1 . A method for controlling a toy helicopter, the helicopter having a first rotor and a second rotor, the first rotor being driven by a first motor, and the second rotor being driven by a second motor, the first motor and the second motor being controlled by a controller remote from the helicopter, power being provided to the first motor and the second motor using pulse width modulation; the first rotor having a first rotor speed and the second rotor having a second rotor speed, the first rotor speed and the second rotor speed being adjusted such that the helicopter is stable in flight, the ratio of the adjusted first rotor speed to the adjusted second rotor speed defining a target ratio; the method comprising the steps of:
 (a) measuring the first rotor speed, measuring the second rotor speed and determining a ratio of the first rotor speed to the second rotor speed;   (b) if the ratio is greater than the target ratio, performing at least one of decreasing the power to the first rotor by a fixed increment and increasing the power to the second rotor by a fixed increment;   (c) if the ratio is less than the target ratio, performing at least one of increasing the power to the first rotor by a fixed increment and decreasing the power to the second rotor by a fixed increment; and   (d) repeating steps (a) to (c) until the ratio and the target ratio are within a predetermined margin;   
       wherein measuring the first rotor speed comprises measuring a feedback voltage of the first motor and measuring the second rotor speed comprises measuring a feedback voltage of the second motor. 
     
     
         2 . The method according to  claim 1 , wherein the second rotor is coaxial with the first rotor. 
     
     
         3 . The method according to  claim 1 , wherein the target ratio relating to rotor speeds is determined by a trim position.