Dan O. Popa, Intro to EE, Spring 2015 EE 1106 : Introduction to EE Freshman Practicum Lecture-Lab 12: Introduction to DC Motors and Control

Dan O. Popa, Intro to EE, Spring 2015 Electric Motor

Dan O. Popa, Intro to EE, Spring 2015 Electric Motors

Dan O. Popa, Intro to EE, Spring 2015 Electric Motor: Electromechanical Model Lorentz Force (EMAG) Faraday’s Law (EMAG), KVL (Electrical) Newton-Euler Law (Mechanical)

Dan O. Popa, Intro to EE, Spring 2015 Position/Speed Control

Dan O. Popa, Intro to EE, Spring 2015 H-Bridges Allows low voltage logic while driving external power to motors. Easily control current in both directions, allowing motors to move forwards and backwards. Useful for DC motors, stepper motors, servos, solenoids, etc. 6

Dan O. Popa, Intro to EE, Spring 2015 H-Bridges Each half bridge is a transistor with an enable. LOW Voltage Input Control Logic HIGH Voltage Output 7 Motor Voltage Logic Enable Motor Logic Input

Dan O. Popa, Intro to EE, Spring 2015 H-Bridge Pinout -EN pins enable output (1 EN pin per pair) -A’s are control inputs -Y’s are outputs -Vcc1 is circuit logic voltage -Vcc2 is the motor supply -Grounds go to ground 8

Dan O. Popa, Intro to EE, Spring 2015 Full-Bridge with DC Motor 9 Motor + - Enable Input A Input B ENABLEInput AInput BResult 110Motor turns CW 101Motor turns CCW 10 or 1 Fast Stop 00 or 1 Free Spin

Dan O. Popa, Intro to EE, Spring 2015 Basic Concepts: Control Machine control refers to a closed-loop feedback system that uses sensory information to control the motion of a machine. A controller accomplishes : –Trajectory tracking – following the prescribed trajectory for the manipulation. –End-point control - reaching a goal configuration in either task or joint space irrespective of the trajectory it is achieved. This is also called the stabilization problem. –Position/velocity control – compensates for errors in knowledge of the systems parameters and suppresses disturbances. Control algorithms can be linear or nonlinear. –Force control – Controlling the force or torque exerted by the motor onto an object in a single or multiple degrees of freedom.

Dan O. Popa, Intro to EE, Spring 2015 Position Control of Servo Motor

Dan O. Popa, Intro to EE, Spring 2015 Position Control of Servo Motor Transfer function (involves s=jω)

Dan O. Popa, Intro to EE, Spring 2015 Torque Control of DC Motor v r = −R m i d

Dan O. Popa, Intro to EE, Spring 2015 Feedback System Block Diagram Automobile Cruise Control

Dan O. Popa, Intro to EE, Spring 2015 Feedback System Block Diagram Temperature control system

Dan O. Popa, Intro to EE, Spring 2015 General Control System Block Diagram

Dan O. Popa, Intro to EE, Spring 2015 Automatic Control Control: process of making a system variable converge to a reference value If r=ref_value=changing - servo (tracking control) If r=ref_value=constant - regulation (stabilization) Open loop vs. closed loop (feedback) control Controller K(s) Plant G(s) + - Sensor Gain H(s) + + Controller K(s) Plant G(s) r r y y

Dan O. Popa, Intro to EE, Spring 2015 Feedback Control Role of feedback: –Reduce sensitivity to system parameters (robustness) –Disturbance rejection –Track desired inputs with reduced steady state errors, overshoot, rise time, settling time (performance) Systematic approach to analysis and design –Select controller based on desired characteristics Predict system response to some input –Speed of response (e.g., adjust to workload changes) Approaches to assessing stability

Dan O. Popa, Intro to EE, Spring 2015 Robots as Complex Systems Controlled by Feedback Robot = an entity that can sense, think and act. Extensions: communicate, imitate, collaborate Classification: manipulators, mobile robots, mobile manipulators. SenseThinkAct Robot

Dan O. Popa, Intro to EE, Spring 2015 Research in Robotics at Next Gen Systems (NGS) Group Robotics Control Systems Manufacturing & Automation Established TechnologiesEmerging Technologies Micromanufacturing Microrobotics Microassembly Micropackaging Sensor & Actuator Arrays NanoManufacturing Microsystems & MEMS Nanotechnology Biotechnology Small-scale Robotics & Manufacturing Modeling & Simulation Control Theory Algorithms Tools and Fundamentals Assistive Robots Human-like robots Distributed and wireless sensor systems New applications for robot systems

Dan O. Popa, Intro to EE, Spring 2015 Final in-class exam information - Prepare a 3 double-sided page cheat sheet covering material in textbook Chapters 1 through 5 that appears in lecture slides. Topics: 1) Basics of electrical units, basic modules (resistor, sources), 2) Ohm’s Laws, KVL, KCL with independent sources, equivalent resistive networks, 3) Nodal Analysis, Mesh Currents, Thevenin, Superposition, Maximum Power Transfer 4) Nonlinear circuit elements: Transistor, Diode, Op-Amp Final in-lab proficiency exam information - Prepare and review your Vis, Code, procedures for all labs. - Practice wiring up a circuit on breadboard, resistor color code, basic measurements (R, V, I) - Produce your lab notebook for inspection. 21 Final Week