{"id":45,"date":"2019-04-07T19:07:48","date_gmt":"2019-04-07T19:07:48","guid":{"rendered":"https:\/\/pressbooks.library.ryerson.ca\/controlsystems\/?post_type=chapter&#038;p=45"},"modified":"2021-01-14T16:50:39","modified_gmt":"2021-01-14T16:50:39","slug":"1-2-types-of-control-actions","status":"publish","type":"chapter","link":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/chapter\/1-2-types-of-control-actions\/","title":{"raw":"1.2 Types of Control Actions","rendered":"1.2 Types of Control Actions"},"content":{"raw":"<p style=\"text-align: justify;\">Note that examples shown here are from Online Control Systems Tutorials that provided illustrations and visualization of basic concepts of Control through streamed video, animations and interactive, self-scoring quizzes.\u00a0 Unfortunately these tutorials are no longer available as they were created using Flash.\r\n\r\n<\/p>\r\n\r\n\r\n[caption id=\"attachment_1195\" align=\"aligncenter\" width=\"592\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1.png\" alt=\"Figure 1-1: Online Tutorials\" width=\"592\" height=\"445\" class=\"wp-image-1195 size-full\" \/> Figure 1-1: Online Tutorials[\/caption]\r\n<p style=\"text-align: justify;\"><strong>1.2.1 Basic Concepts of Feedback<\/strong><\/p>\r\n<p style=\"text-align: justify;\">The diagram below represents basic feedback loop configuration that we will be studying in this course. See more introductory information in the Tutorials online in the section on Basic Introduction to Control Systems.<\/p>\r\n\r\n\r\n[caption id=\"attachment_49\" align=\"aligncenter\" width=\"975\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2.png\" alt=\"Figure 1 2: Diagram showing feedback\" width=\"975\" height=\"352\" class=\"wp-image-49 size-full\" \/> Figure 1-2: Diagram showing feedback[\/caption]\r\n<p style=\"text-align: justify;\">Question: In common sense of the word, positive feedback is good, negative feedback is bad. Would that work for a control system? If yes, why? If no, why? Give examples of positive and negative feedback in real-life systems.<\/p>\r\n<p style=\"text-align: justify;\"><strong>1.2.2 Math of the Basic Feedback Loop<\/strong><\/p>\r\n<p style=\"text-align: justify;\">Consider the basic negative feedback loop in Figure 1\u20113. Derive the Input-Output relationship for this loop, describing the closed loop gain of this system:<\/p>\r\n\r\n\r\n[caption id=\"attachment_53\" align=\"aligncenter\" width=\"300\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-300x171.png\" alt=\"Figure 1-3: Basic Negative Feedback Loop\" width=\"300\" height=\"171\" class=\"wp-image-53 size-medium\" \/> Figure 1-3: Basic Negative Feedback Loop[\/caption]\r\n<p style=\"text-align: justify;\">HINT: Consider these basic blocks and the equations they represent.<\/p>\r\n<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31.png\" alt=\"\" width=\"640\" height=\"188\" class=\"wp-image-1197 size-full aligncenter\" \/>\r\n<p style=\"text-align: justify;\"><strong>1.2.3 Positive Feedback<\/strong><\/p>\r\n<p style=\"text-align: justify;\">Positive feedback leads to instability. Example - putting a powered mike in front of a speaker.<\/p>\r\n\r\n\r\n[caption id=\"attachment_64\" align=\"aligncenter\" width=\"300\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-300x168.png\" alt=\"Figure 1-4: Positive Feedback Loop\" width=\"300\" height=\"168\" class=\"wp-image-64 size-medium\" \/> Figure 1-4: Positive Feedback Loop[\/caption]\r\n<p style=\"text-align: justify;\"><strong>1.2.4 Open Loop Control - No Disturbance Present<\/strong><\/p>\r\n<p style=\"text-align: justify;\">Consider an example in the Tutorials online in the section on Basic Introduction to Control Systems - car driving with no feedback. Let us look at two cases:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>\u00a0No disturbance - flat road<\/li>\r\n \t<li>\u00a0Disturbance - road grade<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\">Case # 1 - No Disturbance Present<\/p>\r\n\r\n\r\n[caption id=\"attachment_67\" align=\"aligncenter\" width=\"718\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5.png\" alt=\"Figure 1-5: Open Loop Control Example\" width=\"718\" height=\"331\" class=\"wp-image-67 size-full\" \/> Figure 1-5: Open Loop Control Example[\/caption]\r\n\r\n[caption id=\"attachment_70\" align=\"aligncenter\" width=\"905\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6.png\" alt=\"Figure 1-6: Open Loop Control\" width=\"905\" height=\"433\" class=\"wp-image-70 size-full\" \/> Figure 1-6: Open Loop Control[\/caption]\r\n<p style=\"text-align: justify;\">Examples of a Simple Open Loop Control:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>\u00a0Lights On\/Lights Off<\/li>\r\n \t<li>\u00a0Toaster<\/li>\r\n \t<li>\u00a0Electric Screwdriver<\/li>\r\n \t<li>\u00a0Programmable Logic Controller<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\"><strong>1.2.5 Open Loop Control - Disturbance Present<\/strong><\/p>\r\n<p style=\"text-align: justify;\">Case # 2 \u2013 Disturbance Present<\/p>\r\n<p style=\"text-align: justify;\">Imagine now driving a car at an intended constant speed (e.g. 100 km\/hr) - to achieve that, you press the gas pedal up to a certain throttle opening. Suddenly the road grade changes - a disturbance occurs. If driven with the same throttle opening, the car will slow down. Conclusion - Open Loop Control cannot handle uncertainty (disturbance).<\/p>\r\n\r\n\r\n[caption id=\"attachment_1199\" align=\"aligncenter\" width=\"828\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5.png\" alt=\"Figure 1 7 Disturbance in Open Loop Control System\" width=\"828\" height=\"376\" class=\"wp-image-1199 size-full\" \/> Figure 1-7: Disturbance in Open Loop Control System[\/caption]\r\n\r\n[caption id=\"attachment_89\" align=\"aligncenter\" width=\"952\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8.png\" alt=\"Figure 1\u20118 Open Loop Control in Presence of Disturbance\" width=\"952\" height=\"531\" class=\"wp-image-89 size-full\" style=\"color: #373d3f; font-weight: bold; font-size: 1em;\" \/> Figure 1\u20118 Open Loop Control in Presence of Disturbance[\/caption]\r\n<p style=\"text-align: justify;\"><strong>1.2.6 Closed Loop Control<\/strong><\/p>\r\n\r\n\r\n[caption id=\"attachment_94\" align=\"aligncenter\" width=\"799\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9.png\" alt=\"Figure 1\u20119 Closed Loop Control Example\" width=\"799\" height=\"371\" class=\"wp-image-94 size-full\" \/> Figure 1\u20119 Closed Loop Control Example[\/caption]\r\n<p style=\"text-align: justify;\">Feedback (Closed Loop) Control can handle uncertainty (both disturbance and parameter drift).<\/p>\r\n\r\n\r\n[caption id=\"attachment_96\" align=\"aligncenter\" width=\"933\"]<img src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10.png\" alt=\"Figure 1\u201110 Closed Loop Control in Presence of Disturbance\" width=\"933\" height=\"527\" class=\"wp-image-96 size-full\" \/> Figure 1\u201110 Closed Loop Control in Presence of Disturbance[\/caption]\r\n<p style=\"text-align: justify;\">Feedback reduces System Error (i.e. difference between Reference and Output) and can minimize the effect Disturbance has on the Output - this action is referred to as Disturbance Rejection.<\/p>\r\n<p style=\"text-align: justify;\">Examples of Closed Loop Control:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>Human Only: walking, sweating (temperature regulation), skateboarding etc.<\/li>\r\n \t<li>Human-in-the-Loop: driving a car (or any other vehicle), adjusting temperature of water in the shower; manual adjustment of settings for a device (e.g. valve, furnace, etc.)<\/li>\r\n \t<li>Automatic Feedback: thermostat heater, any industrial or non-industrial autonomous robot, cruise control in a car, \u201csmart\u201d prosthetics (biofeedback), Dean Kamen's wheel-chair that can climb stairs; gap control in mag-lev (magnetic levitation) system in super-fast trains, balancing of a Segway device, etc.<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\">Systems can have Human-in-the-Loop and Automatic Control at the same time. Example: operating the Segway - at one level, an automatic control system makes sure that the device is balanced in an upright position, on another level, the human operator makes control decisions about direction and speed of travel.<\/p>\r\n<strong>1.2.7 Summary\u00a0<\/strong>\r\n<p style=\"text-align: justify;\">Open Loop Control:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>OK in predictable environments &amp; uncomplicated tasks<\/li>\r\n \t<li>Limitation: Vulnerable to unpredictability (Disturbance)<\/li>\r\n \t<li>Result: Errors occur<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\">Closed Loop Control:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>Robust performance - excellent handling of unpredictability (Disturbance);<\/li>\r\n \t<li>Result: Error reduced or eliminated;<\/li>\r\n \t<li>Limitation: complexity &amp; cost; instability may occur<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\">Differences:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>Open Loop - no attempt to verify the outcome, no feedback, no correction<\/li>\r\n \t<li>Closed Loop - outcome assessed, feedback provided, corrective action taken<\/li>\r\n<\/ul>\r\n<p style=\"text-align: justify;\">Similarities:<\/p>\r\n\r\n<ul style=\"text-align: justify;\">\r\n \t<li>Both have a power source and a certain level of complexity<\/li>\r\n \t<li>Both perform useful tasks.<\/li>\r\n<\/ul>","rendered":"<p style=\"text-align: justify;\">Note that examples shown here are from Online Control Systems Tutorials that provided illustrations and visualization of basic concepts of Control through streamed video, animations and interactive, self-scoring quizzes.\u00a0 Unfortunately these tutorials are no longer available as they were created using Flash.<\/p>\n<figure id=\"attachment_1195\" aria-describedby=\"caption-attachment-1195\" style=\"width: 592px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1.png\" alt=\"Figure 1-1: Online Tutorials\" width=\"592\" height=\"445\" class=\"wp-image-1195 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1.png 592w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1-300x226.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1-65x49.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1-225x169.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.1-350x263.png 350w\" sizes=\"auto, (max-width: 592px) 100vw, 592px\" \/><figcaption id=\"caption-attachment-1195\" class=\"wp-caption-text\">Figure 1-1: Online Tutorials<\/figcaption><\/figure>\n<p style=\"text-align: justify;\"><strong>1.2.1 Basic Concepts of Feedback<\/strong><\/p>\n<p style=\"text-align: justify;\">The diagram below represents basic feedback loop configuration that we will be studying in this course. See more introductory information in the Tutorials online in the section on Basic Introduction to Control Systems.<\/p>\n<figure id=\"attachment_49\" aria-describedby=\"caption-attachment-49\" style=\"width: 975px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2.png\" alt=\"Figure 1 2: Diagram showing feedback\" width=\"975\" height=\"352\" class=\"wp-image-49 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2.png 975w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2-300x108.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2-768x277.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2-65x23.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2-225x81.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_2-350x126.png 350w\" sizes=\"auto, (max-width: 975px) 100vw, 975px\" \/><figcaption id=\"caption-attachment-49\" class=\"wp-caption-text\">Figure 1-2: Diagram showing feedback<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Question: In common sense of the word, positive feedback is good, negative feedback is bad. Would that work for a control system? If yes, why? If no, why? Give examples of positive and negative feedback in real-life systems.<\/p>\n<p style=\"text-align: justify;\"><strong>1.2.2 Math of the Basic Feedback Loop<\/strong><\/p>\n<p style=\"text-align: justify;\">Consider the basic negative feedback loop in Figure 1\u20113. Derive the Input-Output relationship for this loop, describing the closed loop gain of this system:<\/p>\n<figure id=\"attachment_53\" aria-describedby=\"caption-attachment-53\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-300x171.png\" alt=\"Figure 1-3: Basic Negative Feedback Loop\" width=\"300\" height=\"171\" class=\"wp-image-53 size-medium\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-300x171.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-65x37.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-225x128.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3-350x199.png 350w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_3.png 502w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-53\" class=\"wp-caption-text\">Figure 1-3: Basic Negative Feedback Loop<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">HINT: Consider these basic blocks and the equations they represent.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31.png\" alt=\"\" width=\"640\" height=\"188\" class=\"wp-image-1197 size-full aligncenter\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31.png 640w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31-300x88.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31-65x19.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31-225x66.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.31-350x103.png 350w\" sizes=\"auto, (max-width: 640px) 100vw, 640px\" \/><\/p>\n<p style=\"text-align: justify;\"><strong>1.2.3 Positive Feedback<\/strong><\/p>\n<p style=\"text-align: justify;\">Positive feedback leads to instability. Example &#8211; putting a powered mike in front of a speaker.<\/p>\n<figure id=\"attachment_64\" aria-describedby=\"caption-attachment-64\" style=\"width: 300px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-300x168.png\" alt=\"Figure 1-4: Positive Feedback Loop\" width=\"300\" height=\"168\" class=\"wp-image-64 size-medium\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-300x168.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-65x36.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-225x126.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1-350x196.png 350w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_4-1.png 420w\" sizes=\"auto, (max-width: 300px) 100vw, 300px\" \/><figcaption id=\"caption-attachment-64\" class=\"wp-caption-text\">Figure 1-4: Positive Feedback Loop<\/figcaption><\/figure>\n<p style=\"text-align: justify;\"><strong>1.2.4 Open Loop Control &#8211; No Disturbance Present<\/strong><\/p>\n<p style=\"text-align: justify;\">Consider an example in the Tutorials online in the section on Basic Introduction to Control Systems &#8211; car driving with no feedback. Let us look at two cases:<\/p>\n<ul style=\"text-align: justify;\">\n<li>\u00a0No disturbance &#8211; flat road<\/li>\n<li>\u00a0Disturbance &#8211; road grade<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Case # 1 &#8211; No Disturbance Present<\/p>\n<figure id=\"attachment_67\" aria-describedby=\"caption-attachment-67\" style=\"width: 718px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5.png\" alt=\"Figure 1-5: Open Loop Control Example\" width=\"718\" height=\"331\" class=\"wp-image-67 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5.png 718w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5-300x138.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5-65x30.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5-225x104.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_5-350x161.png 350w\" sizes=\"auto, (max-width: 718px) 100vw, 718px\" \/><figcaption id=\"caption-attachment-67\" class=\"wp-caption-text\">Figure 1-5: Open Loop Control Example<\/figcaption><\/figure>\n<figure id=\"attachment_70\" aria-describedby=\"caption-attachment-70\" style=\"width: 905px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6.png\" alt=\"Figure 1-6: Open Loop Control\" width=\"905\" height=\"433\" class=\"wp-image-70 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6.png 905w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6-300x144.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6-768x367.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6-65x31.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6-225x108.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_6-350x167.png 350w\" sizes=\"auto, (max-width: 905px) 100vw, 905px\" \/><figcaption id=\"caption-attachment-70\" class=\"wp-caption-text\">Figure 1-6: Open Loop Control<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Examples of a Simple Open Loop Control:<\/p>\n<ul style=\"text-align: justify;\">\n<li>\u00a0Lights On\/Lights Off<\/li>\n<li>\u00a0Toaster<\/li>\n<li>\u00a0Electric Screwdriver<\/li>\n<li>\u00a0Programmable Logic Controller<\/li>\n<\/ul>\n<p style=\"text-align: justify;\"><strong>1.2.5 Open Loop Control &#8211; Disturbance Present<\/strong><\/p>\n<p style=\"text-align: justify;\">Case # 2 \u2013 Disturbance Present<\/p>\n<p style=\"text-align: justify;\">Imagine now driving a car at an intended constant speed (e.g. 100 km\/hr) &#8211; to achieve that, you press the gas pedal up to a certain throttle opening. Suddenly the road grade changes &#8211; a disturbance occurs. If driven with the same throttle opening, the car will slow down. Conclusion &#8211; Open Loop Control cannot handle uncertainty (disturbance).<\/p>\n<figure id=\"attachment_1199\" aria-describedby=\"caption-attachment-1199\" style=\"width: 828px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5.png\" alt=\"Figure 1 7 Disturbance in Open Loop Control System\" width=\"828\" height=\"376\" class=\"wp-image-1199 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5.png 828w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5-300x136.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5-768x349.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5-65x30.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5-225x102.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/1.5-350x159.png 350w\" sizes=\"auto, (max-width: 828px) 100vw, 828px\" \/><figcaption id=\"caption-attachment-1199\" class=\"wp-caption-text\">Figure 1-7: Disturbance in Open Loop Control System<\/figcaption><\/figure>\n<figure id=\"attachment_89\" aria-describedby=\"caption-attachment-89\" style=\"width: 952px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8.png\" alt=\"Figure 1\u20118 Open Loop Control in Presence of Disturbance\" width=\"952\" height=\"531\" class=\"wp-image-89 size-full\" style=\"color: #373d3f; font-weight: bold; font-size: 1em;\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8.png 952w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8-300x167.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8-768x428.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8-65x36.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8-225x125.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_8-350x195.png 350w\" sizes=\"auto, (max-width: 952px) 100vw, 952px\" \/><figcaption id=\"caption-attachment-89\" class=\"wp-caption-text\">Figure 1\u20118 Open Loop Control in Presence of Disturbance<\/figcaption><\/figure>\n<p style=\"text-align: justify;\"><strong>1.2.6 Closed Loop Control<\/strong><\/p>\n<figure id=\"attachment_94\" aria-describedby=\"caption-attachment-94\" style=\"width: 799px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9.png\" alt=\"Figure 1\u20119 Closed Loop Control Example\" width=\"799\" height=\"371\" class=\"wp-image-94 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9.png 799w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9-300x139.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9-768x357.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9-65x30.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9-225x104.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_9-350x163.png 350w\" sizes=\"auto, (max-width: 799px) 100vw, 799px\" \/><figcaption id=\"caption-attachment-94\" class=\"wp-caption-text\">Figure 1\u20119 Closed Loop Control Example<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Feedback (Closed Loop) Control can handle uncertainty (both disturbance and parameter drift).<\/p>\n<figure id=\"attachment_96\" aria-describedby=\"caption-attachment-96\" style=\"width: 933px\" class=\"wp-caption aligncenter\"><img loading=\"lazy\" decoding=\"async\" src=\"http:\/\/pressbooks.library.ryerson.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10.png\" alt=\"Figure 1\u201110 Closed Loop Control in Presence of Disturbance\" width=\"933\" height=\"527\" class=\"wp-image-96 size-full\" srcset=\"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10.png 933w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10-300x169.png 300w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10-768x434.png 768w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10-65x37.png 65w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10-225x127.png 225w, https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-content\/uploads\/sites\/75\/2019\/04\/fig1_10-350x198.png 350w\" sizes=\"auto, (max-width: 933px) 100vw, 933px\" \/><figcaption id=\"caption-attachment-96\" class=\"wp-caption-text\">Figure 1\u201110 Closed Loop Control in Presence of Disturbance<\/figcaption><\/figure>\n<p style=\"text-align: justify;\">Feedback reduces System Error (i.e. difference between Reference and Output) and can minimize the effect Disturbance has on the Output &#8211; this action is referred to as Disturbance Rejection.<\/p>\n<p style=\"text-align: justify;\">Examples of Closed Loop Control:<\/p>\n<ul style=\"text-align: justify;\">\n<li>Human Only: walking, sweating (temperature regulation), skateboarding etc.<\/li>\n<li>Human-in-the-Loop: driving a car (or any other vehicle), adjusting temperature of water in the shower; manual adjustment of settings for a device (e.g. valve, furnace, etc.)<\/li>\n<li>Automatic Feedback: thermostat heater, any industrial or non-industrial autonomous robot, cruise control in a car, \u201csmart\u201d prosthetics (biofeedback), Dean Kamen&#8217;s wheel-chair that can climb stairs; gap control in mag-lev (magnetic levitation) system in super-fast trains, balancing of a Segway device, etc.<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Systems can have Human-in-the-Loop and Automatic Control at the same time. Example: operating the Segway &#8211; at one level, an automatic control system makes sure that the device is balanced in an upright position, on another level, the human operator makes control decisions about direction and speed of travel.<\/p>\n<p><strong>1.2.7 Summary\u00a0<\/strong><\/p>\n<p style=\"text-align: justify;\">Open Loop Control:<\/p>\n<ul style=\"text-align: justify;\">\n<li>OK in predictable environments &amp; uncomplicated tasks<\/li>\n<li>Limitation: Vulnerable to unpredictability (Disturbance)<\/li>\n<li>Result: Errors occur<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Closed Loop Control:<\/p>\n<ul style=\"text-align: justify;\">\n<li>Robust performance &#8211; excellent handling of unpredictability (Disturbance);<\/li>\n<li>Result: Error reduced or eliminated;<\/li>\n<li>Limitation: complexity &amp; cost; instability may occur<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Differences:<\/p>\n<ul style=\"text-align: justify;\">\n<li>Open Loop &#8211; no attempt to verify the outcome, no feedback, no correction<\/li>\n<li>Closed Loop &#8211; outcome assessed, feedback provided, corrective action taken<\/li>\n<\/ul>\n<p style=\"text-align: justify;\">Similarities:<\/p>\n<ul style=\"text-align: justify;\">\n<li>Both have a power source and a certain level of complexity<\/li>\n<li>Both perform useful tasks.<\/li>\n<\/ul>\n","protected":false},"author":118,"menu_order":2,"template":"","meta":{"pb_show_title":"on","pb_short_title":"","pb_subtitle":"","pb_authors":[],"pb_section_license":""},"chapter-type":[],"contributor":[],"license":[],"class_list":["post-45","chapter","type-chapter","status-publish","hentry"],"part":3,"_links":{"self":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapters\/45","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapters"}],"about":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/wp\/v2\/types\/chapter"}],"author":[{"embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/wp\/v2\/users\/118"}],"version-history":[{"count":52,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapters\/45\/revisions"}],"predecessor-version":[{"id":2744,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapters\/45\/revisions\/2744"}],"part":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/parts\/3"}],"metadata":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapters\/45\/metadata\/"}],"wp:attachment":[{"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/wp\/v2\/media?parent=45"}],"wp:term":[{"taxonomy":"chapter-type","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/pressbooks\/v2\/chapter-type?post=45"},{"taxonomy":"contributor","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/wp\/v2\/contributor?post=45"},{"taxonomy":"license","embeddable":true,"href":"https:\/\/pressbooks.library.torontomu.ca\/controlsystems\/wp-json\/wp\/v2\/license?post=45"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}