201_3
Range of signed integer n-bit
-2^(n-1) to 2^(n-1) - 1
Range of unsigned n-bit integer
0 to 2^n - 1
Structure/body of a robot
A frame or chassis to hold components together
Structure/body
A frame or chassis to the other components together
Analog vs. Digital signal
Analog is continuous in time and values, while digital is discrete
Conversion of Analog inputs
Analog signal must be converted to digital for input and input must be converted to analog for output
Which number systems are suitable for computers
Binary and hexadecimal (computers with large memory addresses)
Benefit of twos complement
Can use existing binary adders without any modifications
Arithmetic and logic unit (ALU) of CPU purpose
Data processing (e.g. adding numbers)
Computer controllers
Decides sequence of actions to take based on sensor movements to achieve objective
Computer controller(s)
Decides the sequence of actions to take (i.e. command the actuators) based on sensor measurements to achieve its objective. Can be a cheap microcontroller or expensive processing system. Depends on processing power required.
Control unit of CPU purpose
Determines timing and sequence of operations
Actuators
Devices that affect the environment
Actuators
Devices that manipulate/affect their environment. Examples: motors, hydraulic or pneumatic cylinders, etc. devices that are able to manipulate the plant's inputs to influence the plant's outputs
Sensors
Devices that measure or detect certain attributes of the environment or the robot itself. Examples: buttons, limit switches, shaft encoders, temperature, light, vision, magnetic, lasers, sonar, etc. measure outputs/signals from the plant
Sensors
Devices that measure/detect things about environment or robot
Find twos complement of -5 in 4 bits
Doko
CPU of microprocessor purpose
Executes program instructions
Using a transistor to control the motor's rotational speed
Feed a high-frequency square wave to the base. Increase the duty cycle for faster speed, decrease for slower. If the frequency is too low, motor keeps starting and stopping or at least changing its speed.
What happens if R is too large in a zener regulator?
For the zener diode t keep voltage constant, it must have current flowing through itself and operate in the breakdown region. If R is too large, when the load draws too much current, V(R) will become too large and V(zener) will drop below the required voltage and I(zener) will be zero.
How is a micro controller programmed
High level language (C) is converted to machine code by compiler or low level language (assembly language) is converted to machine code by assembler program
Advantages of Field Effect Transistors
Higher input impedance: generally we can take the gate current for a FET as zero. Lower power requirement Simple manufacturing process Higher miniaturisation possible
Draw the elements of a Mechatronics system
ILILILILILI
Offset Voltage
If both inputs of an op amp are joined together and grounded, the output voltage should certainly be zero. However, for a real op amp, the output voltage is likely to be very different from zero. It may even be at the positive of negative saturation level.
Clipping
If the input signal is so large that the output voltage tries to exceed these limitations, then the output voltage will be clipped. It will also occur whenever the output tries to exceed the maximum possible output current.
The ideal op amp
Infinite open-loop game. Infinite input resistance zero output resistance infinite bandwidth
Pseudocode
Informal (syntax-wise) way of describing the procedure/algorithm that is easy to read and understand.
Registers purpose in CPU
Internal memory locations to store temporary results while ALU is processing
armDown(float pctPwr);
Lowers the arm to its lowest position (until it hits the lower limit switch) at the given percentage power level.
What is a robot
Machine that can sense environment, act based on senses to do a job and js autonomous
Micro controller vs microprocessor (memory and integrated circuits)
Microprocessor: memory is on separate IC to I/O components. - high processing power and memory e.g. (PC) Micro controller: all on one IC - lower processing power and memory e.g. appliances
More bits means...
More precise and more overall memory locations
Advantages for transistors as switches
Much faster switching. Less power consumption Less current needed to initiate switching Smaller size than relays
ROM Memory (Read Only Memory)
Non volatile memory. Can be read but not written to during execution.
Important factors in choosing a micro controller
Number of ports required, interfaces (e.g. PWM) required, memory requirements, processing speed, number of interrupts if needed
How can the assumption of infinite bandwidth be sensibly made?
Op amps are used with negative-feedback loops. These loops reduce the gain and increase the bandwidth by the same factor. The product of gain and roll-off frequency remains constant.
Uses of dedicated ports
PWM, aerial communication, interrupts etc.
Buses from CPU
Paths which transfer digits signals, could be tracks on circuit board or wires
SRAM (Static RAM)
RAM that does not need to be refreshed as long as power is applied. Faster but more expensive than DRAM.
DRAM (Dynamic RAM)
RAM using capacitors, data must be refreshed due to charge leakage
EEPROM (Electrically Erasable Programmable Read-Only Memory)
ROM that can be electrically erased by high voltage and rewritten repeatedly.
EPROM (erasable programmable read-only memory)
ROM that can be programmed more than once, contents are erased using UV light
PROM memory (programmable ROM)
ROM that can be programmed once by user
armUp(float pctPwr);
Raises the arm to its highest position (until it hits the upper limit switch) at the given percentage power level.
ClearTimer(timerName);
Resets the named timer (T1 to T4) to zero
Drawback of twos complement
Result is super dependent on number of bits
Overflow
Result of addition returns number outside range
time1[timerName];
Returns the specified timer count (integer) in milliseconds units
Sonar
Sends 40kHz ultrasonic pulses and measures the time it takes for the reflected waves to arrive to calculate the distance. Assumes a constant speed of sound. Some surfaces may absorb these ultrasonic waves. Has an apporx. 30° beam angle.
Draw a microprocessor system
Shanna
Use of Digital input-output ports
Some digital ports can be configured to be input or output, some can be used for communication and pulse width modulation
Power source
Source of energy for active sensors and actuators and computer controller
StartTask(taskName);
Starts running the designated task
StopAllTasks();
Stops all running tasks including main()
StopTask (taskName);
Stops executing the designated task
5 parts of a robot
Structure, sensors, actuators, computer controllers, power source
Imperfections in the linear range of operations
The ideal op amp has infinite input impedance, zero output impedance, infinite open-circuit gain, and infinite bandwidth. Real op amps don't quite achieve this level of perfection.
Non-inverting amplifier
The input current is zero, the input impedance is infinite. The output impedance is zero since the output voltage Vo does not depend on the load resistance. An ideal amplifier. Vo = ((R1 + R2)/R1)Vi
Slew Rate
The maximum rate at which output voltage can change. If the output voltage tries to exceed this value, then the required rate-of-change of voltage will be too high and the resultant waveform will not be sinusoidal. Instead, it will be at least partially triangular as the voltage changes at its maximum possible rate.
Power source
The source of energy to power the active sensors and actuators as well as the computer controller. Usually electrical power stored in a battery for mobility.
Amplification for Common-Emitter Amplifier
The varying signal V(s) makes V(BE) vary too, producing corresponding changes in i(c) and, therefore, V(c). The changes in V(C) and V(o) are bigger than those in V(s), hence amplification.
Flow Charts
Used to visually describe the program flow. Do NOT write code in flowchart symbols
Cutoff Region
V(BE) < 0.7 V and i(B) = i(E) = 0
Saturated Region
V(BE) = 0.7 V and V(CE) = 0.2 V
Active Region
V(BE) = 0.7 V and V(CE) > 0.2 V
Difference Amplifier Output Voltage
Vo = (Rb/Ra)(V2-V1)
Integrator circuit
Vo = -(1/RC)int(0 -> t) Vi dt
differentiator circuit
Vo = -RC dVi/dt
RAM (Random Access Memory)
Volatile memory that requires power to hold data.
Flyback/Freewheeling Diode
When the switch is closed, current flows through the motor. When the switch is opened, the current is required to reduce to zero, ideally instantaneously. Provides a way for the current to flow after the voltage is dropped instantaneously. However, the motor contains some inductance, so any very rapid change in current produces a very large voltage which could damage the switch. The diode in the circuit enables the motor current to keep flowing after the switch is opened, so the current can reduce more slowly, and no large voltage spike is produced.
Forward Bias ideal Diode
a voltage is applied across the diode so as to drive conventional current from anode to cathode. Under these conditions the diode is a conductor, and has zero resistance
Monostable Mode for 555 timer IC
an external trigger causes the 555 timer to output a single pulse of adjustable duration. Uses include creating time delays, producing bounce-free switches, touch switches, etc.
Diode
are electronic devices which allow current to flow in one direction only.
Zener Diode
are specifically designed to regulate voltage; unlike most diodes, they are intended to operate in the breakdown region.
Transistor
are three-terminal semiconductor devices: a voltage across one pair of the terminals can be used to control the flow of current through another pair. Their main uses are to amplify of switch electronic signals.
Light Sensors
are used to detect ground colour changes. Can be utilised to follow lines or detect borders. The returned reading for the same colour can be: different for each sensor, affected by external light sources, or varying across a range of values (i.e. not constant).
Timers
are used to measure elapsed time of certain events. They run in the background (wait commands pause the program). Timers use signed 32-bit integers. Tick every 1 millisecond. Start counting when the program starts. Should be reset before overflowing. Will reach 2,147,483,647 ms before overflowing
Transistors as switches
by making use of the cutoff and saturation states
Arm Encoder
can be used to determine the absolute position of the arm. First you must move the arm to one of the known limits (upper or lower) which we know/can measure the real arm angle. Once the arm is there, reset the encoders once. Each robot will have it's unique values for the minimum and maximum arm positions.
Wheel Encoders
can be used to work out the linear distance travelled or the angle turned by the robot assuming no slip.
Summer circuits
circuit which produces a weighted sum of the input voltages. Vo = -(Rf/Ra)Va - (Rf/Rb)Vb
Controller
commands the actuators to manipulate the plant output based on sensor measurements to achieve a desired output.
Operational Amplifier
considered by many to be the most useful single device in analogue electronics. Their characteristics are very often close to ideal. Originally, however, they were used in analogue computers to carry out operations such as addition and differentiation, hence the name.
Optical Shaft Encoders
contains a slotted wheel and a light sensor. As the shaft rotates, the light sensor inside generates a digital signal that correspond to counts per revolution
What happens if R is too small in a zener regulator?
current will be large and flow into the zener diode, thus damaging the diode. More current will lead to waste of energy and heat produced could be dangerous.
Tasks
have to be defined before they are started. Like functions, they have prototypes and their own scope. Unlike functions, they do not have inputs or return arguments
Coupling Capacitors in the Common-Emitter Amplifier
ideally allow AC signals to pass, while blocking DC
Summing point constraint
input currents are zero and the input voltages are equal. Other terms are virtual short circuit and virtual earth principle.
Filter
is a circuit designed to pass inputs in a certain frequency range while blocking other inputs.
Robot
is a system that: Physically exists in the real world; can sense its environment or part of it; can act based sensor measurements to achieve and objective; and is autonomous (not remotely controlled by an operator)
Pulse-width Modulation (PWM)
provides a mich more efficient way to control power delivery than more-traditional approaches, such as a variable resistor in series.
Function
section of code that: is named; is independent; performs a specific task; and can return a value to the calling program. It doesn't execute unless it is called by the main program.
Instrumentation Amplifier
superior version of the difference amplifier where the Vo = (Rb/Ra)(1 + (R2/R1))(V2 - V1)
Astable Mode for 555 timer IC
the 555 timer outputs a periodic waveform of adjustable pulse width and frequency. Uses include keeping time in a circuit, making an analogue synthesiser, or simply making lights flash.
Bistable Mode for 555 timer IC
the 555 timer's output toggles between high and low states in response to the state of its two inputs.
Offset-voltage nulling
the effect of voltage on output voltage can be reduced by balancing the op amp using a potentiometer, and this potentiometer is adjusted until zero input gives zero output.
The inverting amplifier
the output voltage is out of phase with the input voltage. Vo = -(R2/R1)Vi
Plant
the system we are trying to control
Reverse Bias ideal Diode
the voltage is connected in the opposite sense, as if to drive conventional current from cathode to anode. The diode now behaves as an open-circuit, so no current flows.
V = 0.7 V
usual assumption for conducting silicon diodes