CHAPTER 5: THE SYSTEM HARDWARE
5.5 Sensors
5.5.1 Edge Detector Sensor
These sensors can be used to find distance or obstacle avoidance. The selected sensor can be easily integrated with the selected microcontroller using its available libraries.
Working
These sensors transmit a high frequency sound pulses and then receives the reflected echo and then calculate the time taken by the wave to come back. It has two openings at the front. One opening is for the transmitter while the other is for the receiver.
The speed of sound in air is around 341 m/sec. The ultrasonic sensor uses this value to calculate the distance of the object. The formula used is given below
[Mohammad Tahir Aqeil_ 0061012769] 53 Distance = Time x Speed of Sound/ 2
Selected Sensor (Arduino-elektronika, 2017)
Me Ultrasonic Sensor
Features (Arduino-elektronika, 2017):
Arduino library available
Protection against high current
Easily integrated with RJ25 interface
Breakout pins available to connect to jumper wires
Indicators LEDs available for debugging
Detecting range: 3cm~4m, best in 30 degree angle
Figure 29: Selected Sensor for Cleaning Drone (Arduino-elektronika, 2017)
[Mohammad Tahir Aqeil_ 0061012769] 54 5.5.2 Dust Sensor
5.5.2.1 Dust Detection Sensor
These types of sensors are new to the industry, a few sensors were found on the literature and most of these sensors data were under experiment. In this section, the research paper
conclude the available data for such sensors which will be used in panels to detect dust accumulation:
Lunar Dust Detector (DTREM) (Williams, 2017)
This dust accumulation detector was developed by NASA for the purpose of study the effects of lunar environment on the silicon solar cells in terms of dust accumulation, thermal, and radiation.
The detector comprises of two components; the senor component which is held on the housing of the sun shield (In this case the PV panel), and the board which is connected to the data system and include a preamplifier, and power distribution unit.
The sensor package had three 10-ohm-cm n-on-p silicon solar cells, each 1 x 2 cm. The power output of each cell varied from 0 to 150 mV. They were mounted on the top horizontal surface of the dust detector housing. One cell was exposed directly to the environment. The other two were covered with clear fused silica shields of 0.15 mm and 0.51 mm thickness, respectively.
The particle energy required to damage the cells is determined by the thickness of the shield.
The energy threshold for the uncovered cell was 173 keV electrons and 60 keV protons, for the 0.15 mm covered cell 175 keV electrons and 4.25 MeV protons, and for the 0.51 mm covered cell 380 keV electrons and 8.5 MeV protons. Three temperature sensors were also mounted on the housing, one beneath the solar cells and two, one internally and one externally, on a vertical side of the housing. The sensors are high-precision nickle resistance thermometers with a range of 84 to 408 K (Williams, 2017).
[Mohammad Tahir Aqeil_ 0061012769] 55 Product Specification (Williams, 2017):
Mass: 0.27 kg Power (avg): 0.5 W
Sensor based on luminescent glazing
The sensor is published on Clean Techn Environ Policy (2017) a research paper (Fathi &
Abderrezek, 2017). This type of sensor depends on the different impression of the dust concentrations that produces shade effect on the PV panel surface and using a luminescent transparent material that moves along the PV panel. The following figure represents the concept of the sensor processing (Fathi & Abderrezek, 2017):
Figure 30 luminescent Glazing Sensor Concept (Fathi & Abderrezek, 2017)
The figure legends are as follows:
1. Ammeter 2. Photocell
3. Strong edge light 4. Transmitted light 5. Luminescent glass plate 6. LED lamp
7. Incident light
[Mohammad Tahir Aqeil_ 0061012769] 56 8. Luminescent dyes
9. Black box 10. Dust particles
The following figures represent the schematic diagram of the sensor circuit and the resulting output versus the shading percentage:
Figure 31 Electrical Circuit of the LED Driver (Fathi & Abderrezek, 2017)
Figure 32 Darlington Current Amplifier Circuit(Fathi & Abderrezek, 2017)
[Mohammad Tahir Aqeil_ 0061012769] 57
Figure 33Optical Study of Light Transmission (Fathi & Abderrezek, 2017)
Figure 34 Photocurrent from Photocell versus Level of Shading Area (Fathi & Abderrezek, 2017)
***This type of sensors could be replaced by the power output mentoring for each panel to detect deficiencies from the normal operations. The regular maintenance will save the power and the time consumed to clean the whole plant.
5.5.2.2 Dust Concentration Sensor
This type of sensors are known commercially and used for measuring air quality inside contaminate environment such as factories that produces debris due to processes and other usages.
[Mohammad Tahir Aqeil_ 0061012769] 58 These sensor function to assure that the surface of the PV panel are cleaned to the best possible configuration, and control the speed and the output of the air blower to save the power and time required to clean the PV panel.
TELAIRE SMART Dust Sensor SM-PWM-01A
This sensor using the optical method to detect the dust concentration which uses infrared light emitting diode and a photoelectric sensor to detect and reflect the IR LED light by dust
particles in air (TELAIR, 2014)
This sensor can monitor the outdoors dust associated with IAQ monitor.
The sensor general features are (TELAIR, 2014):
Compact size, light weight (about W59x H46x D18 mm, 23g)
PWM (pulse width modulation) output (Low pulse output)
Able to distinguish small particles of cigarette
Smoke from large particles of house dust
The Low pulse width is proportion to particle size and concentration
Constant forced air convection flow by heater resister in dust sensor
Lead free and ROHS directive compliant
Minimum particle size can be detected over 1μm (House dust size: avg 20 μm , yellow dust size: avg 20um, cigarette dust size: avg 1μm)
The electrical data for the sensor are as follows (TELAIR, 2014):
Supply voltage -0.3 to + 7.0 V
Operating temperature -10 to 60 °C
Storage temperature -30 to 80 °C
Current Consumption < 100± 5% mA
Signal output Hi : > 4.5V, Lo : <0.7V,
[Mohammad Tahir Aqeil_ 0061012769] 59
Input impedance 200 kΩ
Pull-Up 10 kΩ
The following represent the circuit schematic of the sensor:
Figure 35 Telaire Smart Dust Sensor Circuit Schematic (TELAIR, 2014)
SAMYOUNG S&C Particle / Dust Sensor Module DSM 501Series
This sensor is able to detect and measure the quantity of dust particles in a space up to 30 m2 (SAMYOUNG S&C, 2012). The dust particles that sensor can detect is as minimum as 1μm and it is ideal for automatic control of air as in the air conditioner, air cleaner, and indoor air quality (IAQ).
The following figure represents a top view of the sensor:
Figure 36 DSM 501 Sensor Top View (SAMYOUNG S&C, 2012)
[Mohammad Tahir Aqeil_ 0061012769] 60 The sensor dimensions:
The following figure represents the sensor measurements:
Figure 37 DSM 501 Sensor Dimensions (SAMYOUNG S&C, 2012)
The sensor main features (SAMYOUNG S&C, 2012):
Quantitative particle density measurement with the principle of particle counter.
Fine particles of bigger than one micron could be detected with high sensitivity.
Inside heater induces air inflow to the module.
The operating conditions:
Supply Voltage 4.5-5.5 V
Power Consumption 90 mA
[Mohammad Tahir Aqeil_ 0061012769] 61
Storage Temperature Range -20/80 °C
Operating Temperature Range -10/65 °C
Operating Humidity Range (without dew condensation) 95 %RH The sensor electrical characteristics are as follows (SAMYOUNG S&C, 2012):
Detectable particle size 1 ㎛.
Detectable range of concentration: 0-15,000 pcs/283㎖
Output signal: PWM (pulse width modulation)
The sensor output characteristics are as follows (SAMYOUNG S&C, 2012):
Vout 1, 2 at high (Vout 1 and Vout 2 are high state when particles are not detected.
(=clean room)) 4.0-4.3 V.
Vout 1, 2 at low (Vout 1 and 2 go to low state when particles are detected) 0.7-1.0 V
Time for stabilization (After the power is turned on) 1 min.
The following figures represents the sensor output at low state:
Figure 38 Sensor Output at Low State (SAMYOUNG S&C, 2012)
The sensor block diagram is as follows:
[Mohammad Tahir Aqeil_ 0061012769] 62
Figure 39 Sensor Block Diagram (SAMYOUNG S&C, 2012)
PM2.5 laser dust sensor
This sensor measures the dust concentration in a unit volume of air typically 0.3:10 micron, and it has a digital output interface. The sensor uses laser scattering theory which depends on the irradiation of laser scattering collection in a specific angle. The output signal is using the scattering light intensity against time curve and uses multiple algorithm to interpret the data to the number of particles according the typical values of particles quantities and sizes.
The following figure represents the sensor general description:
[Mohammad Tahir Aqeil_ 0061012769] 63
Figure 40 PM 2.5 Air Concentration Sensor (Dfrobot, 2017)
Product Specifications(Dfrobot, 2017) :
Operating voltage: 4.95 ~ 5.05V
Maximum electric current: 120mA
Measuring pm diameter: 0.3~1.0、1.0~2.5、2.5~10（um）
Measuring pm range：0~500 ug/m3
Standby current: ≤200 uA
Response time: ≤10 s
Operating temperature range:: -20 ~ 50C
Operating humidity range: 0 ~ 99% RH
Maximum size: 65 × 42 × 23 (mm) Product Features (Dfrobot, 2017):
Quick response
Standard serial input word output
Second-order multi-point calibration curve
[Mohammad Tahir Aqeil_ 0061012769] 64
The minimum size of 0.3 micron resolution The following figure represents the sensor dimensions:
Figure 41 PM2.5 Dust Sensor Dimensions (mm) (Dfrobot, 2017)
The following figure represents the block diagram of the sensor:
Figure 42 Sensor Block Diagram (Dfrobot, 2017)
This sensor has the ability for IO expansion as per the following figure:
[Mohammad Tahir Aqeil_ 0061012769] 65
Figure 43 IO Expansion Ability for the PM2.5 Sensor (Dfrobot, 2017)
5.5.2.3 Product Selection:
The selection criteria for the sensor should be according to:
a. Quantity measuring b. Precise measurement
c. The ability for signal modification d. Incorporate with microcontroller e. Low voltage input
f. Low power consumption
According to the above criteria; the sensor selected is SAMYOUNG S&C Particle / Dust Sensor Module DSM 501Series. This senor is precise for measuring quantities of dust concentration (0-15,000 PCs), the ability of the signal modulation for different ranges (low, average, high) which is suitable for the air blower speed control, low voltage input (4.5 V to 5.5) these value are average values since other sensors may exceed these input voltage values, and the power consumption for this sensor is low due to low current consumption compared to the other sensors (90 mA for the selected sensor).
5.6 Air Blower
Different air blowers are found in the market, the following are some types of air blowers that satisfy the weight constraint for the driving drone (1.5-2 Kg):
[Mohammad Tahir Aqeil_ 0061012769] 66 5.6.1 60x60x15mm 5V solar blower fan 12V dc blower fan
Figure 44 Yofon Air Blower (Shenzhen Yofolon Electronic, 2017)
The product specifications (Shenzhen Yofolon Electronic, 2017):
Type: Axial Flow Fan
Electric Current Type: DC
Mounting: Screw fixing Blade Material: Plastic
Place of Origin: Guangdong, China (Mainland)
Brand Name: YOFOLON
Model Number: DB6015B05H
Voltage: 5V-12V
Power: 2.5W
[Mohammad Tahir Aqeil_ 0061012769] 67
Air Volume: 4.85CFM
Speed: 4200RPM
Certification: CE, ROHS, UL Bearing Type: Two Ball Rated Current: 0.5A
Static Pressure: 11.36mmH2O Noise Level: 37.68dBA
Fan Life: 50,000 Hours
Weight: 35 g
4.6.2 ANENG R1G133-H045-01F
Figure 45 ANENG Air Blower (Shanghai Anneng Fan, 2017)
Product Specification (Shanghai Anneng Fan, 2017):
Type: Centrifugal Fan
Electric Current Type: DC
Blade Material: galvanized steel
[Mohammad Tahir Aqeil_ 0061012769] 68 Mounting: Free Standing
Place of Origin: Shanghai, China (Mainland)
Brand Name: Anneng
Model Number: R1G133-H045-01F
Power: 40 W
Voltage: 12V / 24V / 48V
Air Volume: 255 m3/h
Speed: 2000 rpm
Certification: CCC, CE, ROHS
Motor: Brushless External Rotor Motor
Rotor: Electrophoresis
Type of Protection: IP44 or IP55 Insulation class: Class "B" or "F"
Bearing: NMB Ball bearing
Life Time: 40000h+
Color: Black
Weight: 1.4kg
Cable Length: 450 mm
[Mohammad Tahir Aqeil_ 0061012769] 69 4.6.3 WORX 32-Volt AIR Multi-Purpose Blower/Sweeper/Cleaner
With 120 MPH / 80 CFM Output, 4 lb. Weight, with 8 Attachments – WG575.1 (Worx, 2017)
Figure 46 WORX Air Blower and Attachments (Worx, 2017)
Product Specifications (Worx, 2017):
Item Dimensions 8 x 7 x 20 inches
Item Weight 4.1 pounds = 1.86 Kg
Manufacturer Part Number WG5751
Manufacturer Warranty Description 3-Year Warranty
Model Number WG5751
Voltage 32 Volts
[Mohammad Tahir Aqeil_ 0061012769] 70 5.6.4 Makita DUB182Z 18V LXT Lithium-Ion Cordless Blower
Figure 47 Makita Air Blower 32V (Makita, 2017)
Product Specification (Makita, 2017):
Item Dimensions 7.2 x 12.7 x 6.4 inches
Item Weight 3 pounds = 1.36 Kg
Manufacturer Part Number DUB182Z
Manufacturer Warranty Description 3 years
Model Number DUB182Z
Style Name Short nozzle
Voltage 18 Volts
[Mohammad Tahir Aqeil_ 0061012769] 71 4.6.5 Black & Decker 20v Lithium Hard Surface Sweeper Blower
Figure 48 Black and Decker Air Blower 20V (Peterr900, 2017)
Product Specifications (Peterr900, 2017):
120 MPH sweeper easily clears debris from hard surfaces like driveways, decks, and garages.
Powerful 20V MAX* Lithium Ion Battery holds a charge up to 18 months.
Lightweight at just 3.7 pounds, the hard surface sweeper is easy to handle with one hand for quick cleanup.
Low noise design allows for quiet operation
Part of the 20V* MAX System - A System that Demands Attention
*Maximum initial battery voltage (measured without a workload) is 20 volts. Nominal voltage is 18.duct
4.6.6 Product Selection
The selection criteria of the product should be according to the following:
a. Light weight
[Mohammad Tahir Aqeil_ 0061012769] 72 b. Low power consumption
c. Variable speed d. Low noise levels e. Powerful output.
According to the selection above the best possible choice is Makita DUB182Z 18V LXT Lithium-Ion Cordless Blower.
This device is light weight (only 3 pounds = 1.36 Kg), the power consumption are low (18 V), variable speed (0-18000 rpm), up to 12 minutes continuous work in high speed, and rechargeable lithium batteries.
5.7 Batteries
The batteries required are for the air blower, microcontroller and sensors uses mostly. The batteries should able to supply the rated voltage for each component attached to the battery with a descent operating time before recharging.
The selected air blower input voltage is 18 V The selected microcontroller input voltage is 5 V The selected sensor input voltage is 5.5 V
The selected battery should able to supply 18 V (Could be regulated from lower voltage supply i.e 12 V or 6 V etc…) while other devices may assumed to have voltage regulator to obtain the required supply voltages. In this section the selection of battery will be directly from products available online since connecting several devices may lacks the homogenous supplication of power characteristics and the operating time that the batteries can afford. This stage may require the alteration of any product had been chosen above to match the available power supply in terms of voltage, current, and frequency.
[Mohammad Tahir Aqeil_ 0061012769] 73 5.7.1 Single cell batteries (1S):
5.7.1.1 Hawker, Gates, EnerSys Cyclon 0810-0075 Assembly Battery 1x6 ABS:
The following figure represents the general view of the battery:
Figure 49 Hawker, Gate, EnerSys Battery (OSIBATTERIES, 2017)
The battery main features are as follows (OSIBATTERIES, 2017):
Pure Lead-Tin VRLA AGM Design
Superior Deep Discharge Recovery
High Rate Charge and Discharge
Two Year Shelf Life
200+ Full Depth Discharge Cycles
Operating Temperature Range -65°C to +80°C
The battery specifications are as follows (OSIBATTERIES, 2017):
Chemistry: Sealed Lead Acid
Voltage: 12 volts
Nominal Capacity: 2.5Ah
Dimensions (L x W x H) in: 8.25 x 1.55 x 2.74
[Mohammad Tahir Aqeil_ 0061012769] 74
Weight (pounds): 2.4
*** The battery weight may be inappropriate for the designed load specification for the robot weight.
5.7.2 Double cell batteries:
5.7.2.1 Hyperion LiPo Battery
The following figure representing the general view of the battery:
Figure 50 Hyperion LiPo 2S Battery (Hyperion-World, 2017)
The product general features (Hyperion-World, 2017):
Contains 2 Lithium-Polymer Batteries
Nominal voltage of 3.7V
Capacity is 2500 mAH (2.5 AH)
The safest charge rate for most LiPo batteries is 1C
Proper LiPo Storage Voltage = 3.8V per cell
Weight: 205 grams
Dimensions: 105.5 x 34.1 x 26.8mm
Discharge Rate: 50Cmax (50C burst, 25~30C continuous)
Power Connector: XT-60
[Mohammad Tahir Aqeil_ 0061012769] 75
Balance Connector: JST-XH
5.7.3 Triple cell batteries:
5.7.3.1 11.1V, 4000mAh, 40C 3S LiPo Battery
The following figure represents the general view of the battery:
Figure 51 11.3 3S LiPo Battery (Robotshop, 2017)
The general features of the battery are as follows (Robotshop, 2017):
4000mAh rechargeable LiPo battery
Voltage: 3S 11.1V LiPo (rechargeable)
Continuous discharge rate (maximum): 40C (160A)
Charging connector: 4-pin JST
The general product specifications are as follows:
Continuous discharge rate (maximum): 40C (160A)
[Mohammad Tahir Aqeil_ 0061012769] 76
Capacity: 4000mAh (4 Ah)
Lead Length: 4" (XT60), 2" (JST)
Connector: XT60 (female)
Charging connector: 4-pin JST
5.7.4 Product Selection
The selection criteria of the battery could be summarized as the following, however on the practical test will reveal the matching battery or the matching components for the system to operate:
a. Higher capacity b. Light weight c. Smaller dimensions
d. Higher continuous discharge rate
The primary selection of the battery is the 11.1V, 4000mAh, 40C 3S LiPo Battery, alterations may take place when assembling the prototype as explained above.
5.8 Chassis
The chassis is designed to be carried by a drone and be able to contain other components including the air blower. The chassis has a special designed tube and openings that direct the air flow from the blower to the front of the robot. At the front of the chassis, there are specific sensor holder that will be used to mount sensors that will detect edges. At the top of the chassis there is an arch that has two slits at the top where drone’s legs can slide in. The back of the chassis will accommodate the air blower. Other components can be scattered under the blower’s tube. The following figures have a different views of the model with some labels.
[Mohammad Tahir Aqeil_ 0061012769] 77
Figure 52 Chassis 3D model perspective view
Figure 53 Chassis 3D model side front view
A: These two groves are for the drone’s legs. They helps the chassis to be lifted by the drone.
B: These two pieces are for mounting edge detectors. They are angled at 45º.
C: This is the front part of the designed tube that direct air flow from the blower to the front of the robot.
[Mohammad Tahir Aqeil_ 0061012769] 78 D: This hole is for mounting the motors and wheels.
Figure 54 Chassis 3D model side back view
E: This is the back part of the designed tube that direct air flow from the blower to the front of the robot.
F: This is the back of the chassis. IT is where the blower will be placed. Other components will be spread under the tube E.
Figure 55 Chassis 3D model top view
[Mohammad Tahir Aqeil_ 0061012769] 79 A: These two groves are for the drone’s legs. They helps the chassis to be lifted by the drone.
Figure 56 Chassis 3D model bottom view
G: This is a stand where a 3rd wheel can be mounted.
Figure 57 Chassis 3D model without the arch side view
F: This is the back of the chassis. IT is where the blower will be placed. Other components will be spread under the tube E.
G: This is a stand where a 3rd wheel can be mounted.
[Mohammad Tahir Aqeil_ 0061012769] 80
Figure 58 Chassis 3D model without the arch top view
Figure 59Chassis 3D model without the arch top back view
[Mohammad Tahir Aqeil_ 0061012769] 81
Figure 60 Chassis 3D model without the arch angled back view
[Mohammad Tahir Aqeil_ 0061012769] 82
CHAPTER 6: ELECTRONICS CONFIGURATION 6.1 Circuit Diagram
Figure 61 System’s circuit diagram
[Mohammad Tahir Aqeil_ 0061012769] 83 6.2 Microcontroller
Arduino Uno board has ATmega328p microcontroller which is powerful and fulfils the system’s needs. Arduino Uno runs on 16MHz crystal and provide easy connections pins.
Figure 62Arduino UNO schematic
6.2.1 Motor Driver
Figure 63 motor driver schematic
To run the motors a L293D dual full H bridge IC is used. As it can be seen from figure there is an enable terminal for each H bridge. In order to activate an H bridge this pin must be tied to logic 1. Both terminals are tied to high to activate H bridges. Now high signal on IN1 will appear on OUT 1 but with more power so motor can be driven by microcontroller signal, same happens for all other control pins terminals.
[Mohammad Tahir Aqeil_ 0061012769] 84 6.2.2 Blower driving Circuit
Figure 64 schematic of driving circuit for blower
A 5v relay is used to switch on and off blower from a pin of microcontroller. When pin is high it sends 5 volts to the base of BC547 transistor which in turn allow current to pass through it.
This current energizes the relay and NO (Normally Open) terminal of relay become normally close so it will behave same as someone just pressed the switch of blower.
6.2.3 Light sensor
Figure 65 light sensor schematic
LED and LDR are used to transmit and detect reflected light from the surface of Solar panel.
When the robot is in the air, there will be no reflection and LDR will receive nothing but when the robot is on the surface of solar panel some light will get back on LDR by reflection and then sensor send signal to microcontroller to activate corresponding logic.
[Mohammad Tahir Aqeil_ 0061012769] 85 6.2.4 7805 5V regulator IC
Figure 66schematic of 7805 5V regulator IC
This IC convert voltage up to 12 volts to constant 5VDC. It is used to power up all the circuits.
6.2.5 Motors
5v dc brushed motors are used to drive robot assembly.
6.2 Circuit Simulation
The simulation was done by using Proteus. The following are the simulation of the circuit at different situations.
6.2.1 When robot is in the Air
As the edge detection sensor is not getting any reflected light, it means the robot is in the air and all motors are in OFF state.
Figure 67 circuit diagram when the robot in the air
[Mohammad Tahir Aqeil_ 0061012769] 86 6.2.2 When robot is on solar panel surface:
The robot is on the surface of the panel and it starts to move forward.
Figure 68 circuit diagram when robot is on solar panel surface
[Mohammad Tahir Aqeil_ 0061012769] 87 6.2.3 When front sensor is out and in again:
The front sensor is out of panel’s surface. So, the motors are stopped.
Figure 69 circuit diagram when front sensor is out and in again
[Mohammad Tahir Aqeil_ 0061012769] 88 6.2.4 When right sensor is out and in again:
The right sensor is out of the panel’s surface. Thus, the robot is turning left by stopping the left motor until the sensor is back on the surface again.
Figure 70 circuit diagram when right sensor is out and in again
Figure 70 circuit diagram when right sensor is out and in again