David GiandomenicoBasic Feedback Control 5/15/2012 David Giandomenico Team mentor for Lynbrook Robotics – FIRST #846 David Giandomenico Team mentor for Lynbrook Robotics – FIRST #846 Steady State Error in Feedback Control

David GiandomenicoBasic Feedback Control 5/15/2012 Open-Loop Control System Out G E.S.C. + − + − Input Speed or Position (joystick, preset button, autonomous, etc.)

David GiandomenicoBasic Feedback Control 5/15/2012 Simple System No Feedback – “ Open Loop ” In Out H H CPU+ESC+Motor+Robot

David GiandomenicoBasic Feedback Control 5/15/2012 System Error In Out

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System “ Closed Loop ” In Out  + − H A Error = ( In – Out) CPU ESC + Motor + Robot

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System “ Closed Loop ” In Out  + − H A Error = ( In-Out) CPU ESC + Motor + Robot

David GiandomenicoBasic Feedback Control 5/15/2012 Error in Feedback System In Out  + − A Error = ( In-Out) CPU ESC + Motor + Robot

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System w/Feed Forward InOut (Velocity)  + H Error = (Out – In) CPU ESC + Motor + Robot  + − − A

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System w/Feed Forward In Out  + − H A Error = ( Out-In) CPU ESC + Motor + Robot  + −

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System w/Feed Forward In Out  + − H A Error = (Out-In) CPU ESC + Motor + Robot  + −

David GiandomenicoBasic Feedback Control 5/15/2012 Static Error in Feedback System w/Feed Forward In Out  + − H A Error = (Out-In) CPU ESC + Motor + Robot  + −

David GiandomenicoBasic Feedback Control 5/15/2012 Comparison: Steady State Error Open Loop  0.1 Out/In 0.90 Error % Basic Closed Loop A15  0.1 H(s) = 1+  1.1 AH(s)16.5 System Gain (Target=1.00) Out/In Error % Estimate of Error: =[A(1+  )] % With Feed-Forward A15  0.1 H(s) = 1+e1.1 AH(s)16.5 System Gain (Target=1.00) Out/In Error % Estimate of Error: =  /A %

David GiandomenicoBasic Feedback Control 5/15/2012 David Giandomenico Team mentor for Lynbrook Robotics – FIRST #846 David Giandomenico Team mentor for Lynbrook Robotics – FIRST #846 Steady State Error in Feedback Control

David GiandomenicoBasic Feedback Control 5/15/2012 Error in System In Out H

David GiandomenicoBasic Feedback Control 5/15/2012 Feedback System “ Closed Loop ” In OutG H + −

David GiandomenicoBasic Feedback Control 5/15/2012 Undesired Feedback Path

David GiandomenicoBasic Feedback Control 5/15/2012 Tip: Setting Gain Fast Option 1: Recompile and upload. Bleah! Option 2: Attach a potentiometer to an analog input (once adjusted, hardwire in code). Not Bad! Option 3: Use EEPROM/Flash Memory to save values. Access values through Operator Interface buttons. Display values on robot or OI. Way Cool!

David GiandomenicoBasic Feedback Control 5/15/2012 Simple Speed and Position Test Setup Neodymium Magnet Qty 2, for balance. (see the web, eBay!) R/C Hobby Prop Adapter, 1/8 ” Custom disk with holes for shaft and magnets Hall effect magnetic sensor <$2 at digikey or mouser

David GiandomenicoBasic Feedback Control 5/15/2012 Closed-Loop Control System Yet more sensors: Accelerometers & Gyros Optical Distance Meas. Cameras, Ultrasonic : Yet more sensors: Accelerometers & Gyros Optical Distance Meas. Cameras, Ultrasonic : Out G Sensor Potentiometer, Encoder, Gear Tooth Sensor, Hall effect Sensor, … E.S.C. + − + − Input Speed or Position (joystick, preset button, autonomous, etc.)