"Wisdom begins in wonder" – Socrates
Tag: Controls
Feedback
08/21/17
“Can an output be used to affect input?”
Systems take an input and produce an output. However, a portion of this output can be cycled back to affect the input as feedback. Feedback that makes the input smaller is known as negative feedback while ones that make the input larger is known as positive feedback. Negative systems are much more stable while positive ones tend to instability. Feedback is vital for closed loop control systems.
All Pass Systems
08/21/17
“What are systems with a constant frequency response magnitude for all frequencies?”
We know that control systems are dependent upon frequency responses and that the magnitude of these responses is usually dependent on the input frequency. However, some systems have a constant frequency response magnitude for all input frequencies, which are termed All Pass Systems.
Step Response
08/21/17
“What is the reaction to an abrupt change in conditions for a system?”
Complex systems are easily controlled by external forces, such as the flip of a switch. And when these forces do cause change, they can be quite quick and drastic, changing all of the conditions of the system. And since the reaction to such changes can be very quick and drastic as well, engineers and scientists have decided to term these changes as the step responses to the system. An example of a step response includes a mechanical body’s friction to moving forces.
Electric Compensators
08/20/17
“How can we control object characteristics of a control system?”
When we have control systems, we often have object characteristics that we desire but are not implemented. For example, we might want to have the phase shift of an output signal to achieve peak frequency at a certain value. Well, after many years of hard work, engineers have invented compensators to accomplish this task. Compensators can be commonly found in PID control systems and electrical power systems.
Minimum Phase Systems
08/20/17
“What do we call systems that have all poles and zeros inside the unit circle?”
Systems that have all poles and zeros inside the unit circle are very special. Why? Well, because with these systems, their causal system will be completely stable and will have a phase lag less than a system of identical magnitude. Since these systems are so special, controls and signal engineers have termed them Minimum Phase Systems.
Unity feedback
08/19/17
“When is the output unchanged from the input of a control block?”
In control systems, the output of a control block is usually modified from the input. However, when there is no change, the process is said to be in unity feedback
Closed-loop Summing Points
08/19/17
“What are the points on a control diagram for comparing the output and the setpoint?”
What makes a closed-loop control system truly closed loop is the comparison of the output and setpoint for making the error value. However, how is this represented on a control diagram? Well, Control Engineers like to use something called a Closed-loop Summing Point. Closed-loop Summing Points are small circular elements on a diagram that takes in an input on one quadrant, the setpoint on another and then produce the error term. Depending on the signs of the quadrant, the input value might be positive (for a + sign) or negative (for a – sign)
Tracking control
08/18/17
“How can we measure the disturbance between a setpoint and an output?”
When a closed loop control system sends an output, it must be compared to an initial setpoint. This process is known as tracking control and is one of the most fundamental parts of every control system
Closed-loop Control Systems
08/18/17
“How can we have a self-correcting control system?”
Open loop control systems may be affordable, but the lack of control over them (pun intended) makes them useful for only select applications. So how can we fix this problem? Well, what if every time our system was to produce an output, we compare it to our setpoint, and then modify the process to achieve our desired result accordingly? This is the fundamental idea behind a closed-loop control system and is used in a vast array of controls applications from electric vehicle battery life monitoring to drones and even laundry machine monitoring.
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