Feedback/Control Systems

Feedback and Control:

Feedback loops are used to design control systems.

There are three types of feedback systems:

• sensing
• giving the robot the ability to sense - such as touch, sight, or movement
• computation
• taking in data and making use of it
• actuation:
• the end result, output, what the robot actually does

There are three types of control:

• open loop
• computing the input using only the most current state of the model
• cheap and feedback is not essential
• closed loop
• bang-bang
• feedback controller with two options: on or off
• proportional-integral-derivative (PID)
• feedback controller capable of calculating an error value and adjusting with calculated error

Motion Light Switch: 

Sensing Mechanism:  

A light switch senses movement.

Control Computation:

This uses bang-bang control.  The light switch will take the data from the sensor and make it work.  For example, when someone enters a room, the sensor will automatically sense movement and the lights will turn on.  After a certain amount of given time, when no movement has been detected, the lights will turn off again.

Actuation Mechanism: 

Turning the light switch on and off will not only turn on the lights but also turn on the movement sensor.

Air Conditioning:

Sensing Mechanism:

An air conditioner senses temperature change in the room.

Control Computation:

Using bang-bang control, the sensor will sense the temperature and turn on or off based on the temperature in the room.  For example if we set the temperature at 70 degrees, the air conditioner runs around that temperature.

Actuation Mechanism:

The air conditioner will be on until the temperature in the room is a little above the set temperature.

Automatic Hand Dryer:

Sensing Mechanism:

A Hand Dryer also senses distance.

Control Computation:

This also uses bang-bang control.  When hands come a certain distance from the hand dryer, it turns off, otherwise, hands are not near the dryer and it turns off.

Actuation Mechanism:

The hand dryers stay on until the hands are a certain distance away from the hand dryer.

Gas Pumps:

Sensing Mechanism:

Gas pumps sense air pressure in the tank.

Control Computation:

In the nozzle is a pipe called venturi which measures the pressure due to the amount of gas in the tank.  As the level of gas rises, the pressure increases and the venturi pipe automatically stops the flow of gas from the nozzle.

Actuation Mechanism:

Gas pumps continuously pump gas into the car until the air pressure is met.