ME 4SS3 L14 Smart Systems Lectures PDF

Smart Systems ME 4SS3 Dr. S. Andrew Gadsden Department of Mechanical Engineering, McMaster University L14.1 Introduction to Signal Conditioning L14.2 Operational Amplifier L14.3 Filtering L14.4 Pulse Width Modulation L14.5 Electromagnetic...

Smart Systems ME 4SS3 Dr. S. Andrew Gadsden Department of Mechanical Engineering, McMaster University L14.1 Introduction to Signal Conditioning L14.2 Operational Amplifier L14.3 Filtering L14.4 Pulse Width Modulation L14.5 Electromagnetic Interference  Monday Wednesday Thursday Deliverables (Virtual on A2L or MS Teams) (HH 305) (HH 305) - - L01: Introduction 09/04 L02: Introduction to 09/05 - to Course Project L03: Introduction to 09/09 L04: System 09/11 L05: Project - Laser 09/12 - Smart Systems Modeling I Cutting (JHE A104A) L06: System Modeling 09/16 L07: System Modeling 09/18 L08: Project - Assembly 09/19 - Practice II Check and Testing L09: System Modeling 09/23 L10: System Modeling 09/25 L11: Project - Modeling 09/26 Assignment 1 and Matlab I and Matlab II Examples (09/29) No Class 09/30 L12: Control Theory 10/02 L13: Project - Matlab 10/03 - (Truth and Simulation Reconciliation) L14: Signal 10/07 L15: Controllers 10/09 L16: Project - 10/10 - Conditioning and Matlab Arduino Tutorial Where are we? No Class 10/14 No Class 10/16 No Class 10/17 Assignment 2 (Thanksgiving Monday) (Break) (Break) (10/20) L17: Kalman Filter I 10/21 L18: Kalman Filter II 10/23 L19: Project – TA 10/24 - Consultations L20: Kalman Filter and 10/28 L21: Introduction to 10/30 L22: Project - TA 10/31 Assignment 3 L14 - Smart Systems Matlab Artificial Intelligence Consultations (11/03) L23: Machine Learning 11/04 L24: Resume 11/06 L25: HR Industry 11/07 Assignment 4 Techniques Workshop (Online) Panel (In-Person) (11/10) L26: Machine Learning 11/11 L27: Review of Smart 11/13 L28: Project - TA 11/14 Resume Asgmt. Applications Systems Material Consultations (11/17) Virtual Office Hours on 11/18 L29: Midterm Review 11/20 L30: Midterm 11/21 Midterm MS Teams and Help (11/21) Virtual Office Hours on 11/25 L31: Project - TA 11/27 L32: Project - 11/28 Project Demo MS Teams Consultations (11/28) 2 Demonstration Day * Check A2L for Virtual Office Hours on 12/02 Virtual Office Hours on 12/04 Project - Report Due 12/05 Project Report the latest schedule MS Teams MS Teams (No Class) (12/05) 14.0 L12 Quiz Smart Systems 1. What does PID stand for?... 2. What does changing the proportional gain do? 3. What does changing the integral gain do? 4. What does changing the derivative gain do? L14 - Smart Systems 3 14.1 Signal Conditioning Introduction The output signal from the sensor of a measurement system has generally to be processed in some way to make it suitable for next stage of operation For example:  The signal may be too small and have to be amplified  Signal may contain interference which needs to be removed  Signal may be nonlinear, and require linearization L14 - Smart Systems  Signal could be analogue, and needs to be made digital  Be a resistance change and have to be made into a current change… All of these scenarios can be referred to as signal conditioning 4 14.1 Signal Conditioning Introduction The main processes that can occur in conditioning a signal may be summarized as follows: 1. Protection to prevent damage to the next element  E.g., a microprocessor due to high current or voltage (could use series current-limiting resistors or fuses) 2. Getting the signal into the right type of signal L14 - Smart Systems  E.g., make the signal into a D.C. voltage or current (such as the resistance change of a strain gauge converted into a voltage change – how do we do this?) 3. Getting the level of the signal right  E.g., using an operational amplifier to amplify a signal (such as in a thermocouple) 5 14.1 Signal Conditioning Introduction The main processes that can occur in conditioning a signal may be summarized as follows: 4. Eliminating or reducing noise  E.g., filters might be used to eliminate noise from a signal (this is often the most common type of signal conditioning) 5. Signal manipulation L14 - Smart Systems  E.g., making it a linear function of some variable (consider the signals from a flowmeter that are nonlinear and a signal conditioner could make the reading linear) 6 14.1 Signal Conditioning Introduction L14 - Smart Systems What is Signal Conditioning? (Part 1) by Dataforth (2014) Link: https://www.youtube.com/watch?v=XFF-v99Zvbs 7 14.1 Signal Conditioning Introduction L14 - Smart Systems What is Signal Conditioning? (Part 2) by Dataforth (2014) Link: https://www.youtube.com/watch?v=DEn4rnEEioM 8 14.2 Signal Conditioning Operational Amplifier An amplifier can be considered to be essentially a system which has an input and an output The voltage gain of the amplifier is the ratio of the output and input voltages when each is measured relative to the earth The input impedance of an amplifier is defined as the input voltage divided by the input current L14 - Smart Systems The output impedance is the output voltage divided by the output current 9 14.2 Signal Conditioning Operational Amplifier The basis of many signal conditioning modules is the operational amplifier The ‘op amp’ is a high-gain D.C. amplifier (gain is typically 100,000 or more) that is supplied as an integrated circuit on a silicon chip It has two inputs:  Inverting input (–) L14 - Smart Systems  Non-inverting input (+) Other inputs may include a positive and negative voltage supply 10 14.2 Signal Conditioning Operational Amplifier An ideal model for an operational amplifier is an amplifier with an infinite gain, infinite input impedance, and zero output impedance (i.e., the output voltage is independent of the load) Different types of circuits may be used with operational amplifiers when used as signal conditioners:  Inverting amplifier  Non-inverting amplifier L14 - Smart Systems  Summing amplifier  Integrating and differentiating amplifiers  Difference amplifier  Logarithmic, comparator, and real amplifiers 11 14.2 Signal Conditioning Operational Amplifier L14 - Smart Systems What is an Operational Amplifier? by Khan Academy (2016) Link: https://www.youtube.com/watch?v=lJDjWZqhpVc 12 14.3 Signal Conditioning Filtering The term filtering is used to describe the process of removing a certain band of frequencies from a signal and permitting others to be transmitted The range of frequencies by a filter is known as the pass band, the range not passed as the stop band, and the boundary between stopping and passing as the cut-off frequency L14 - Smart Systems Filters may be classified according to the frequency ranges they transmit or reject  Low-pass, high-pass  Band-pass, band-stop 13 14.3 Signal Conditioning Filtering A low-pass filter has a pass band which allows all frequencies from zero up to some frequency to be transmitted A high-pass filter has a pass band which allows all frequencies from some value up to infinity to be transmitted A band-pass filter allows all the frequencies within a specified band to be transmitted L14 - Smart Systems A band-stop filter stops all frequencies with a particular band from being transmitted 14 14.3 Signal Conditioning Filtering In all cases, the cut-off frequency is defined as being that at which the output voltage is 70.7% of that in the pass band The term attenuation is used for the ratio of input and output power (units of dB) The output voltage of 70.7% of that in the pass band is an attenuation of 3 dB (note that 20 log10 0.707 = 3) L14 - Smart Systems The term passive is used to describe a filter made up using only resistors, capacitors, and inductors The term active is used when the filter also involves an operational filter 15 14.3 Signal Conditioning Filtering Low-pass filters are very commonly used as part of signal conditioning  Most of the useful information being transmitted is low frequency  Since noise tends to occur at higher frequencies, a low-pass filter can be used to block it off  E.g., a low-pass filter with a cut-off frequency of 40 Hz may block off any interference signals from the A.C. main supply and noise in general L14 - Smart Systems (why?) Low-pass filters typically improve the signal-to-noise ratio (the higher, the better!) In MATLAB, you can check out the ‘butter’ function  Type ‘help butter’ in the command window 16 14.3 Signal Conditioning Filtering L14 - Smart Systems An RC Low-Pass Filter Circuit Example by Electronics Learning (2016) Link: https://www.youtube.com/watch?v=NGAbFUIBajk 17 14.4 Signal Conditioning Pulse Width Modulation If a signal is a sequence of pulses rather than a continuous-time signal, you can minimize drift issues Pulse amplitude modulation modifies a signal as if it were being ‘discretized’ L14 - Smart Systems 18 14.4 Signal Conditioning Pulse Width Modulation Pulse width modulation (PWM) is widely used with control systems as a means of controlling the average value of a D.C. voltage If there is a constant analogue voltage and it is chopped into pulses, the average value of the voltage can be changed by varying the width of the pulses L14 - Smart Systems Duty cycle is the fraction of each cycle for which the voltage is ‘high’ 19 14.4 Signal Conditioning Pulse Width Modulation L14 - Smart Systems What is PWM? by Afrotechmods (2008) Link: https://www.youtube.com/watch?v=YmPziPfaByw 20 14.5 Signal Conditioning Electromagnetic Interference Electromagnetic interference is an undesirable effect on circuits resulting from time-varying electric and magnetic fields Common sources include fluorescent lamps, D.C. motors, relay coils, household appliances, and the electrics of ‘motor cars’ Electrostatic interference occurs as a result of mutual capacitance between neighbouring conductors L14 - Smart Systems Interference also occurs when there is a changing magnetic field which induces voltages in the measurement system 21 14.5 Signal Conditioning Electromagnetic Interference How do you protect or minimize the effects?  Electric shielding (e.g., using electrically conductive material such as copper or aluminum)  Twisted pair of cables for interconnections may minimize electromagnetic interference  Physically placing components far apart may minimize magnetic interference L14 - Smart Systems 22 14.5 Signal Conditioning Electromagnetic Interference L14 - Smart Systems Electromagnetic Interference as Fast as Possible by Techquickie (2015) Link: https://www.youtube.com/watch?v=AHbrVad86xw 23 L14 Summary Key Takeaways Signal conditioning: the output signal from the sensor of a measurement system has generally to be processed in some way to make it suitable for next stage of operation The basis of many signal conditioning modules is the operational amplifier The term filtering is used to describe the process of removing a certain band of frequencies from a signal and permitting others to be transmitted (e.g., low-pass filter) L14 - Smart Systems PWM is widely used with control systems as a means of controlling the average value of a D.C. voltage EMI is an undesirable effect on circuits resulting from time-varying electric and magnetic fields 24  Monday Wednesday Thursday Deliverables (Virtual on A2L or MS Teams) (HH 305) (HH 305) - - L01: Introduction 09/04 L02: Introduction to 09/05 - to Course Project L03: Introduction to 09/09 L04: System 09/11 L05: Project - Laser 09/12 - Smart Systems Modeling I Cutting (JHE A104A) L06: System Modeling 09/16 L07: System Modeling 09/18 L08: Project - Assembly 09/19 - Practice II Check and Testing L09: System Modeling 09/23 L10: System Modeling 09/25 L11: Project - Modeling 09/26 Assignment 1 and Matlab I and Matlab II Examples (09/29) No Class 09/30 L12: Control Theory 10/02 L13: Project - Matlab 10/03 - (Truth and Simulation Reconciliation) L14: Signal 10/07 L15: Controllers 10/09 L16: Project - 10/10 - Conditioning and Matlab Arduino Tutorial What’s next? No Class 10/14 No Class 10/16 No Class 10/17 Assignment 2 (Thanksgiving Monday) (Break) (Break) (10/20) L17: Kalman Filter I 10/21 L18: Kalman Filter II 10/23 L19: Project – TA 10/24 - Consultations L20: Kalman Filter and 10/28 L21: Introduction to 10/30 L22: Project - TA 10/31 Assignment 3 L14 - Smart Systems Matlab Artificial Intelligence Consultations (11/03) L23: Machine Learning 11/04 L24: Resume 11/06 L25: HR Industry 11/07 Assignment 4 Techniques Workshop (Online) Panel (In-Person) (11/10) L26: Machine Learning 11/11 L27: Review of Smart 11/13 L28: Project - TA 11/14 Resume Asgmt. Applications Systems Material Consultations (11/17) Virtual Office Hours on 11/18 L29: Midterm Review 11/20 L30: Midterm 11/21 Midterm MS Teams and Help (11/21) Virtual Office Hours on 11/25 L31: Project - TA 11/27 L32: Project - 11/28 Project Demo MS Teams Consultations (11/28) 25 Demonstration Day * Check A2L for Virtual Office Hours on 12/02 Virtual Office Hours on 12/04 Project - Report Due 12/05 Project Report the latest schedule MS Teams MS Teams (No Class) (12/05) Additional Resources Smart Systems Slides (PDF) and relevant code will be found on the course page within Avenue to Learn Relevant textbooks and resources are referenced in the syllabus or within the slides Please contact me if you have any difficulties throughout the course L14 - Smart Systems 26