Transcript Behavior-Based Robotics

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
+
M
S1
MOTOR
To P1.6 on MSP430
Q1
MPS8098
Dan O. Popa, Intro to EE, Spring 2015
V1
3V
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.
Dan O. Popa, Intro to EE, Spring 2015
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H-Bridges
• Each half bridge is a transistor with an
enable. Motor Voltage
Logic Input
Logic Enable
Motor
Dan O. Popa, Intro to EE, Spring 2015
• LOW Voltage Input Control Logic
• HIGH Voltage Output
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H-Bridge Pinout
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•
•
•
•
•
-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
http://www.ti.com/lit/ds/symlink/l293d.pdf
Dan O. Popa, Intro to EE, Spring 2015
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Full-Bridge with DC Motor
Input A
Enable
+
Motor
-
Input B
Dan O. Popa, Intro to EE, Spring 2015
ENABLE
Input A
Input B
Result
1
1
0
Motor turns CW
1
0
1
Motor turns CCW
1
0 or 1
0 or 1
Fast Stop
0
0 or 1
0 or 1
Free Spin
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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
vr = −Rm id
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
r
Controller
K(s)
Plant
G(s)
+
+
y
r
Controller
K(s)
+
Sensor Gain
H(s)
Dan O. Popa, Intro to EE, Spring 2015
Plant
G(s)
y
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.
Sense
Think
Robot
Dan O. Popa, Intro to EE, Spring 2015
Act
Research in Robotics at
Next Gen Systems (NGS) Group
http://ngs.uta.edu
Tools and Fundamentals
Established Technologies
Modeling & Simulation
Microsystems &
MEMS
Robotics
Control Systems
Control Theory
Nanotechnology
Manufacturing &
Automation
Algorithms
Assistive Robots
New applications
for robot systems
Emerging Technologies
Human-like robots
Distributed and
wireless sensor
systems
Dan O. Popa, Intro to EE, Spring 2015
Biotechnology
Small-scale
Micromanufacturing
Robotics &
Microrobotics
Manufacturing
Microassembly
Micropackaging
Sensor & Actuator Arrays
NanoManufacturing
Final Week
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.
Dan O. Popa, Intro to EE, Spring 2015
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