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Key Concepts and Terminology

VEX IQ Curriculum - Smarter Machines

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 first have an understanding of what Control is and the types of control systems that can be created.

Control, simply, is defined 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 five 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 difficult 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 +/- differences between desired and actual results and correct for those differences 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.