260 likes | 512 Views
QUIZ PREP. Have Quiz sheet ready. Title = QUIZ 8 Name (L, F, MI), Today’s date 10/9/12 , Lab day , time section number. Announcements. First professional memo due today in lecture. Submit when called for.
E N D
QUIZ PREP • Have Quiz sheet ready. Title = QUIZ 8 • Name (L, F, MI), • Today’s date 10/9/12, • Lab day , time • section number
Announcements • First professional memo due today in lecture. Submit when called for. • The preliminary design report is due at the beginning of your Week 10 lab mtg. • The final design report is due at the beginning of Week 13 lab.
Design Reports: Audience • Design reports: Target audience is a busy technical manager, not … • Dr. Roppel • Your GTA • Mom • Team members • General public
Design Reports: Audience Characteristics of your target audience: • Very limited time to comprehend your results. Can’t / won’t dig through fluff. Make results jump off the page. • Technically savvy, but not familiar with your project details (you must suspend reality here to get it right – role playing).
Scores on Canvas • Check your scores on Canvas • If they are not right or not posted after two weeks, check with your GTA. • If you still need help, email me or see me in person. • All memos graded at same time, even if you submitted early.
Announcements • Format and grading rubric for the Design Reports are on the class website and syllabus.
Announcements • Each TEAM bring the following to lab this week: • Motor control board • Transmitter/receiver pair (check batteries – voltage should be above 10.0 V). • Two motors • R1 and R2 that will give you 10 to 12 V.
Resistors • Can use resistors in lab for this week’s experiment. • You need to obtain your own for your car. • Science supply store (best option) • Radio Shack • Online (shipping cost!)
Pulse Position Modulation - PPM • “Regular” or “Differential” PPM • Used for simplicity • Inexpensive, lightweight RX • Fine for R/C; not great for general communications
Differential PPM Six Channels, all zero (center stick) except Channel 3 (right stick). 1 2 6 5 4 3 time Easier to decode – just need to detect time between two pulses. Differential PPM is what our setup uses.
Servos and Op-Amps • Servos are special motors that include control circuitry. Used for precise control of position or velocity • DC servos are used in R/C and robots. AC servos are common in industry. • Op-Amps are important analog circuits. Used for amplifying, filtering, isolation, and motor control.
DC Servos Web link
Servos Purchase servos locally at Hobbytown USA
Servos Position vs. Pulse Width • Input is a PWM signal; motor responds by turning to a fixed position. Example:
Other Servo Types • Continuous Rotation (control speed and direction) • Digital • AC
Continuous Rotation Servos • Can be purchased or can modify traditional servos. • “Neutral” signal (e.g. 1.5 ms) yields no movement. • PW >1.5 ms yields CW rotation. PW < 1.5 ms yields CCW rotation. • Great for driving robots.
Digital Servos • Use a microprocessor to analyze incoming signal and perform motor control. • Higher pulse rate (300 Hz vs. 50 Hz) yields faster response, less deadband, more holding power. • ‘After flying digital servos, analogue versions are like controlling custard’ • Tradeoff: use more power.
AC Servo Motors • Typically used for factory automation
Op-Amps • Operational Amplifier • Developed circa 1940 by Bell Labs for telephone amplification. • Used for artillery aiming in WWII. • Analog computers • Now: input “pretreatment” and output buffering for DSP.
Example Op-Amp Circuit Inverting Amplifier
Op-Amp Circuit Analysis VX Gain = A Very large 0
QUIZ PREP • Have Quiz sheet ready. Title = QUIZ 8 • Name (L, F, MI), • Today’s date 10/9/12, • Lab day , time • section number
Quiz 8: Page 1 of 2 Write the correct answers on your Quiz sheet. 1. For a technical report, the use of lists, bullets, and headers should be avoided. TRUE / FALSE 2. The appropriate reader for whom you should target your design reports is: Dr. Roppel / Busy Manager / Mom 3. Differential PPM encodes joystick position as: Absolute pulse position / Space between pulses / Pulse width
Quiz 8: page 2 of 2 4. For standard servos, position is determined by: Absolute pulse position / Space between pulses / Pulse width 5. Operational amplifiers are used primarily to: Calculate trajectories / Perform signal processing 6. Op-amps have internal voltage gain that is: Very small / Very large