Robotics

default directory for the Apache server on the pi?

/etc/apache2

what does 'bash' mean

Born Again Shell

why is unix/linux admin important?

b/c the world runs on linux

what command-line command do you type to determine the search order for finding commands that you type?

echo $PATH

what does ps -ef do?

shows every process on the system

what is the difference between ln, cp, and mv commands?

ln : creates a link cp: copies mv: moves

what 'crontab' can do?

sets a command to run at specific times or intervals

what does the 'df' command provide?

shows disk freespace

what does the 'du' Command provide?

shows disk usage

describe what 'at' can do

similar to crontab, 'at' can set a command to run in a certain amount of time or at a moment in time

what command do you use to change your password in linux?

$passwd

If you do not use parallel programming or multi-threading in program , what character do you type at the end of a command line to run a linux program in the background?

&

what file would you modify if you wanted to auto run a command immediately after the pi is booted?

/etc/rc.local or /etc/init.d

what directory is used to configure most of the linux server and security files?

/etc/security

Name of configuration file that needs to be modified so you can use filezilla?

/etc/vsftpd/conf

what are the two configuration files that you modified to make the pis accessible thru putty ??

/etc/wpa_supplicant/wpa_supplicant.conf and /etc/dhcpcd.conf

what system directory provides most of the commands for command-line instructions. The /usr dir is the parent dir

/usr/bin

5 decision criteria for deciding on which architectural control structure to use

1) Noise: sonar & actuator 2) Environment: dynamic & stable 3) Speed: sensing & movement 4) learn new behavior 5) hardware: can/does the machine sense/remember to map out

what is the approximate data rate (bits per second) for data traveling to Mars?

128-250 kb/s

How many digital cameras does it take to try to sense distance?

2

why is a diode important when driving a servo motor?

A diode allows current to flow in one direction. Protect the flow from reversing the motor.

What would be the drawback of using 12 distance sensors?

A massive power drain from using and computing data from 12 sensors. It would be very complicated to coordinate/combine the code for all of them.

describe behavioral control

A mix of other control architectures to give a robot personality in reacting to the environment

Why is parallelism important in programming controllers?

A robot needs to do multiple actions at once, the language needs to execute many rules with multitasking.

Is a break beam detector a passive or active sensor?

Active

Name one things that causes photocells to be inaccurate

Ambient Light

What is AI as it applies to robotics?

An advanced form of autonomy in which the robot is able to move and achieve goals on its own

What is a robot

An autonomous system that senses its environment & acts on it to achieve its goals

What is an effector?

Any device on a robot that has an effect on the environment

Why is a break beam detector active?

B/C it is a reflective optosensor that operates on reflected light

Why do robots tend to shake when they move?

B/c of pulse width modulation

What does BBC stand for?

Behavior Based Control

differences between behavior-based control and hybrid-based control

Behavior based modules have more than 3 modules in paralled but BBC does not have deliberation

levels of abstractions, why those readings are important to reading and reacting to what happens in robotics' controller

Behaviors take differing times and details Abstraction makes things less detailed for flexibility this helps to ensure the time-table

What are the four main components in a robot?

Body, controller, effectors, sensors

Describe how the two maps in the book, relate to each other and how one can be used to help program the robots movements

Both are different representations of the same map. They show the decisions at each turn.

Subsumption Architecture

Build systems incrementally. Systems build up layers that each do a task. High layers assume existence of lower layers.

What does CCD stand for?

Charge Coupled Device

Describe teleoperation

Completely or mostly controlled by a human

What is a disadvantage of using two digital cameras to sense distance?

Computes distance depth by using perspective & makes assumptions about the environment

______ is the mathematical study of the properties of automated control systems ranging from steam engines to airplanes and much in between

Control Theory

What are the two most common types of motors used in robots?

DC and H-Bridge

What is DOF and what does it mean?

Degrees of Freedom, the dimensions in which a manipulator can move

When talking about a motor, what does DC stand for?

Direct Current

How is edge detection achieved using digital cameras?

Finds sharp changes in pixel brightness

Describe deliberate Control

Follows a time-based "map-based" plan

Why is edge detection important?

Identifying & avoiding objects

Describe how mutually exclusive conditions from robotics' sensors can provide information that will help the programs controlling the controller react appropriately to achieve its goal.

It can trigger a unique action and make precise instructions on what to do next

A robot's program has a very accurate map programmed with precise pulses and pulse-widths programmed into its controller. It needs to navigate a maze that does not move and there are no surprise obstacles possible. Why would hybrid control be more desirable than deliberative control?

It would not need to sense its environment and scan for updates.

What are two advantages of lase sensors over sonar sensors?

Laser is more accurate and travels and the speed of light

What are charge coupled devices used for?

Light detection, image sensors

At what speed does data travel to and from satellites orbiting Mars?

Light speed

List three types of exteroceptive sensors

Light, Thermometer(external), sonar, IR sensitive, ultrasonic distance, color sensors

Name four types of sensors used in robotics

Light, distance, temperature, motion

Give three examples of what proprioceptive sensors do`

Measures battery level, wheel position, thermometer sensing internal temperature

List three types of actuators

Motors, hydraulics, Lasers

Name three causes of error in sonar sensor readings

Moving objects, angled objects, specular reflection

Describe the paths that these rovers are following, how they are being directed and why the rover using PID is normalizing closer to a straight line.

PID remembers its errors so it wont make them again, slowly coming to a straight line due to that aspect.

What is the difference between passive and active sensors?

Passive sensors: measure physical property from the environment & use a detector Active sensors: provide their own signal & consist of emitter

What are the three layers that must be programmed to create hybrid control?

Planning, middle, reactive

Describe the PD Controller

Proportional Differential: moves proportionally to feedback from distance sensor in account to time

Describe the PID Controller

Proportional Integral Differential: same as PD but keeps track of accuracy by summing errors & effectiveness of correctness

Describe the P Controller

Proportional: system responds in proportion to the error from feedback by distance sensor

What changes in a photo cell so it can detect "darkness" vs "light"?

Resistance

Describe "magnitude of error"

Robot knows how far off it is from the goal ( the distance to the goal state)

What does SPA stand for?

Sense, Plan, Act

What do you call it when you use more than one type of sensor?

Sensor Fusion

What are Exteroceptive sensors?

Sensors that tell the robot about the world around it

What manipulator links are we using to move our camera and launcher?

Servo

What to you call the problem of getting an intelligent response from a processor as a result of an output from a sensor reading? s________to s_______

Signal to Symbol

Which requires more signal processing, sonar or odometry?

Sonar

What does Sonar stand for?

Sound Navigation Ranging

When sonar transducer sends an ultrasonic pulse toward an object, it delivers a cone-shaped pulse that sometimes does not get received correctly by the receiver. The pulse reflects in a manner that occasionally does not provide accurate readings. This is known as ________ reflections

Specular

Describe "direction of error"

Tells the robot which motor to move. Minimizing error to getting closer to the goal

What is autonomy?

The ability to make ones own decisions and act on them

What is an actuator?

The mechanism that enables an effector to execute an action or movement

Describe how PWM is used to move the SG90 Tower Pro Servo

The orange wire uses pulse width modulation to close the circuit when voltage is applied from the controller

Describe how SPA is used to control achieving a goal using a motor-driven rover.

The robot navigates through a series of obstacles by interpreting its surroundings , thinks , then moves

Describe how static stability, COG, and the "polygon of support" are related

They all have an effect on the robot standing upright. COG affects the static stability (maintaining balance while not moving) and the COG is the center point of the polygon of support, the ground points(legs/wheels) make the edges of the POS

What is one disadvantage of laser sensors vs sonar sensors?

They are more expensive and larger , the small beam cant cover an area unless it sweeps

If using sonar sensors to determine distance from a wall or object, what is the advantage of using multiple sensors?

They can triangulate readings to compute a more accurate distance.

Why might you need more than one controller in a robot?

To partition different functions to separate controllers. For examples separate calculations and sensor reading from motor functions.

T/F : Robotic involves autonomy, sensing, action, and achieving goals all in the physical world

True

T/F: Perception requires input from sensors, controller computation, and wires to get input from sensors to the controller

True

What can a potentiometer be used for?

Tune sensitivity of sliding & rotating mechanisms

Why cant we hear pulses sent by sonar?

Ultrasound wave frequency is not in the human hearing range

What is the disadvantage of using multiple sensors?

Uses more power and software has to be connected

What is a potentiometer?

Variable resistor used to calibrate sensors

Explain BBC?

Works to bring time-scales together

describe topological map

a series of landmarks with links connecting them. Tells the robot what to do at each point.

command to make shell script named "doit" rwx by owner, rx by group and no access to other id

chmod 750 doit.sh

Describe hybrid control

combination of reactive and deliberative control

take pics on motion detection and auto load them to another linux server?

dd if $source of $destination

List two reasons why facial recognition is so difficult

edge detection is difficult, shadows and contours

what is the significance of /etc/sudoers file?

it controls who has super-user (god mode) priviledges

Why did we use Python for our rovers?

it has good scripting capabilities and there are a lot of libraries with code.

Why is representation more than just remembering data from robots sensors?

it needs a sense of history and its place in order to plan.

what command do you use to list, long way, all files in /home/pi/bin

ls -a /home/pi/bin

Differences between off-line and on-line planning?

off-line: stores plans for later use on-line: is in-the-moment planning

Describe Analog I/O

one that is continuous in time and amplitude, converts to digital for computer processing

Describe Digital I/O

ones + zeros input from a sensor that gets converted

What is the name of the package that can be used to create a window server on linux?

samba

Describe Reactive Control

specific reactions are defined for a robot

In robotics, describe how is sonar used to determine distance

time is started when emitter sends a ping and is stopped when reflected ping returns, it takes the return time to calculate distance.

why did we use /home/pi/bin

to create services to run automatically

why do you need "sudo" part in "sudo ptyhon runme.py"?

to run it as the super-user (GOD MODE)

why a separate directory for pybin?

to store the .py files and executables

Define a waveform

up and down pattern of pulses

What linux commmand would you issue to read the internal temp of the pi and convert it to degrees Farenheit?

vcgencmd measure_temp

How many minutes does it take data to travel to and from Mars (one direction)?

~1200 minutes