Guide

Robot
Brain
Robot
Actions
Sensor Feedback
Control
Commands
Actual
Result
(Robot position,
velocity, etc.)
Desired
Result
Robot
Brain
Robot
Actions
Control
Commands
Actual
Result
(Robot position,
velocity, etc.)
Desired
Result
K.2
Key Concepts and Terminology
Learning to manipulate and use your VEX IQ controller well is one way to gain better control over
your robot, but that is a purely Teleoperated solution. What about Autonomous and Hybrid robots?
Well, you’ve already seen in the Smart Machines Unit that using sensors and programming to create
desirable Autonomous and Hybrid solutions can lead to some amazing solutions. Before furthering
your programming skills to create more advanced solutions, you must rst have an understanding
of what Control is and the types of control systems that can be created.
Control, simply, is dened as the ability to direct the actions or function of something. Having better
Control over your VEX IQ creations will lead to seeing more expected repeatable behavior and more
positive results in general. Open-Loop Control Systems are also called Non-Feedback Control
Systems. This type of control system is generally more simplistic and easier to implement. It cannot
correct for errors or disturbances along the way. In the Open-Loop Control System shown below,
a desired result is programmed and/or sent to the Robot Brain, the Robot Brain sends control
commands to the robot’s subsystems, telling them to take certain actions, and those actions lead
to an actual result. Using the VEX IQ Smart Motors to drive straight forward autonomously for ve
seconds is one example of Open-Loop Control.
Systems that utilize feedback are called Closed-Loop Control Systems. These systems tend
to be more complex and more dicult to implement, but can often lead to more repeatable and
predictable control. The feedback in a Closed-Loop Control System, like the one shown below,
is used to recognize +/- dierences between desired and actual results and correct for those
dierences along the way. Using the VEX IQ Gyro Sensor to maintain a constant heading/direction
while a robot drives autonomously is one example of Closed-Loop Control.
Open-Loop or Closed-Loop, Which is Best for Me?
There is no one answer. Control System type choices depend on your time, resources, expertise,
the environment your robot will be operating in, the level of control and error correction that you
need or desire, and any other constraints that are presented before you.