This is to test the system capability to distribute messages to several robots using only one coordinator. Each "robot" is only an arduino fio board, with a xbee modem, and at the computer side, there is a module (program) for each "robot". These modules send a message each 100 ms, and at the robot side the boards blink a led to signal the message was received.
Although the tests had good results, its hard to assess if no delay is present on the messages. If one robot is turned off, that affect the others. Only three destination modems were used in this test, and there is a difference between a modem that was previously used in other tests and the other two modems that were just recently put in use.
Further investigation must focus in why a modem shut down affect the others and what is the difference in the configuration of the two "new" modems and the "old" one.
Sunday, December 19, 2010
Saturday, December 18, 2010
ARToolKit Plus
After several tests with the ARToolkit, I found it to be somewhat limited regarding the flexibility of changing the code. So I decided to try the ARToolKitPlus:, which is written in C++, it is very flexible in configuring my setup and it is still maintened.
Today I performed the calibration to the wide angle lens I am using, and managed to track markers up to a distance of 700 mm from the camera, in an area of approximately 1200 x 1200. It is a very loose setup, so further tests are required. However the results are very promising, as I believe this distance is being limited only by the camera resolution (640x480) which can be increased if I use other cameras.
This toolkit is already integrated in the LARToolkit!
Today I performed the calibration to the wide angle lens I am using, and managed to track markers up to a distance of 700 mm from the camera, in an area of approximately 1200 x 1200. It is a very loose setup, so further tests are required. However the results are very promising, as I believe this distance is being limited only by the camera resolution (640x480) which can be increased if I use other cameras.
This toolkit is already integrated in the LARToolkit!
Thursday, December 9, 2010
To do
- Robots: test new arduinos with new car chassis, must find an h-bridge that is specified for 3.3V, although the l293 that is currently being used at the prototype might work (although it specifies a minimum low logic of 4.5V).
- Arena: integrate the ARToolkit into the LAR Toolik, test maximum camera height, resolution, and minimum markers size.
- Xbee: test messaging with one coordinator and several endnodes.
- Tests: integrate RVO2 Library - Reciprocal Collision Avoidance for Real-Time Multi-Agent Simulation into LAR Toolkit!
Tuesday, December 7, 2010
Quick reminders
- ARToolKit: just made some tests with this increadible toolkit. I am going to use this to track the robots position and orientation on the arena. Still have to validate this approach, testing camera height, field of view, robustness, integration with the lar toolkit.
- test several xbee messaging: just remembering that I turned off the acknowledge request that was part of a transmit message, this was causing the lag when messages were being sent to a xbee modem that was turned off.
- test several xbee messaging: just remembering that I turned off the acknowledge request that was part of a transmit message, this was causing the lag when messages were being sent to a xbee modem that was turned off.
Thursday, November 25, 2010
problem with multiple xbee modems II
The problem persisted even if I did not checked in my software the response.
However, once I turn on the "second" modem things work out just fine. The "second" modem was the one to whom once messages started being sent interfered with the normal working of the modem at the robot. Why??
I am not sure, but at least the problem is narrowed to the Xbee modems, maybe a configuration that can be set via XCTU...
More on that later...
However, once I turn on the "second" modem things work out just fine. The "second" modem was the one to whom once messages started being sent interfered with the normal working of the modem at the robot. Why??
I am not sure, but at least the problem is narrowed to the Xbee modems, maybe a configuration that can be set via XCTU...
More on that later...
problem with multiple xbee modems
I am currently going through some major problems. So far tests were just fine when using only one coordinator an one destination modem (both router and endnode). However when I tried to use a setup with 3 modems (coordinator + router + endnode) I am experiencing serious lags in communication, for example the gamepad commands take very long to arrive the destination.
In this tests, there is a program that sends messages at a rate of 2Hz, destinated to a modem that is not turned on. (this may be one of the problems, I remember now that once I powered that other modem, things were fine, or am I mistaken?).
Anyway, I am trying to figure out now where is the bottleneck in this setup. I may be in the way I am handling messages at the computer, it may be hardware limitations (xbee buffer, serial channel speed, wireless comm speed...).
In this tests, there is a program that sends messages at a rate of 2Hz, destinated to a modem that is not turned on. (this may be one of the problems, I remember now that once I powered that other modem, things were fine, or am I mistaken?).
Anyway, I am trying to figure out now where is the bottleneck in this setup. I may be in the way I am handling messages at the computer, it may be hardware limitations (xbee buffer, serial channel speed, wireless comm speed...).
robot base validation videos
these three videos show initial tests and final results in constructing a robot based on a rc car chassis. the first video shows the command of the steering angle using an arduino that is receiving commands from the keyboard of a laptop:
the second video shows the robot being remotely commanded by a gamepad via a xbee modem:
the third video is a test of the robot actually moving on the laboratory floor, commanded by a gamepad:
the second video shows the robot being remotely commanded by a gamepad via a xbee modem:
the third video is a test of the robot actually moving on the laboratory floor, commanded by a gamepad:
New arduino fio
This is a picture of the new arduino board to be used in this project. It is very small, has an integrated Xbee socket and a LiPo charger. The new power source (LiPo 1000mAh) is also in that picture.
Here is a comparison between the duemilanove and the fio boards:
Here is a comparison between the duemilanove and the fio boards:
Wednesday, November 24, 2010
Xbee api + robot
Today I manage to repeat the setup that could command the robot base using the gamepad, via xbee. However the xbee modem is working in API mode. The message payload has three bytes, the first one is used to provide the signal of direction and speed, the second is the direction value and the third is the speed.
The results are much better compared to the older implementation using xbee AT mode. This may be due to the data structure that is now being used.
Now I will post pictures and videos of the completed robot at this point, as it will be unmounted to test the new arduino fio board, with the new 3.7v power supply.
I still want to test the robot behaviour when the coordinator is also sending messages to other modems.
The results are much better compared to the older implementation using xbee AT mode. This may be due to the data structure that is now being used.
Now I will post pictures and videos of the completed robot at this point, as it will be unmounted to test the new arduino fio board, with the new 3.7v power supply.
I still want to test the robot behaviour when the coordinator is also sending messages to other modems.
Wednesday, November 17, 2010
xbee api library
Finally (thanks to the invaluable help of Jorge Almeida) I managed to port the arduino xbee library to C++. According to the library website (xbee-arduino) the code could depended only on the serial library and on the millis function. The millis were substituted by the "gettimeofday" function, and the serial lib was substituted by our lab serial lib, written by Ricardo Pascoal.
I managed to compose and send an API packet from a computer program as well as receive and parse a package.
Next step is to cleanup the code, and use the new xbee lib in the program that will be responsible for sending/receiving messages to the modems.
I managed to compose and send an API packet from a computer program as well as receive and parse a package.
Next step is to cleanup the code, and use the new xbee lib in the program that will be responsible for sending/receiving messages to the modems.
Monday, November 15, 2010
Developments update
Currently I am working creating a xbee api library, so I can create a program that easily send and receives messages through a network of xbee modems, being able to address an individual modem, and being able to know who sent a specific message.
There are already some resources regarding such libraries, even one for arduino, which was tested and worked just fine: xbee-arduino library.
Now I have to adapt that code to be able to run in a Linux machine.
There are already some resources regarding such libraries, even one for arduino, which was tested and worked just fine: xbee-arduino library.
Now I have to adapt that code to be able to run in a Linux machine.
Friday, November 12, 2010
remote command
The current test is the ability to command the robot via a Xbee link, with the lar toolkit at one end, sending messages from the Xbox gamepad.
So far it was found that the xbee devices, (at least while working in AT mode) can have significant delay when the COORDINATOR tries to send messages. According to this forum: XBee series 2 - receiving delay, a possible reason is that the COORDINATOR tries to broadcast messages, while a ROUTER or END NODE, by default, unicast messages to the coordinator, so now the COORDINATOR modem is at the robot and the ROUTER modem is at the command center. It is important to emphasize that the modems will be configured as API in the future, to deal with multiple robots, and it is unknown how good the xbee message rate will be.
So far it was found that the xbee devices, (at least while working in AT mode) can have significant delay when the COORDINATOR tries to send messages. According to this forum: XBee series 2 - receiving delay, a possible reason is that the COORDINATOR tries to broadcast messages, while a ROUTER or END NODE, by default, unicast messages to the coordinator, so now the COORDINATOR modem is at the robot and the ROUTER modem is at the command center. It is important to emphasize that the modems will be configured as API in the future, to deal with multiple robots, and it is unknown how good the xbee message rate will be.
steer control - dc motor with potentiometer II
I managed to get the steer control working. There is still some fine tunning to be performed, as for now there is a tolerance of 40 units among the approximate range of 300 units sweeped by the motor in an analogic read. Factors that affect the tunning are: motor voltage, noise in readings, serial outputs...
The car is being powered with a 9V NIMH battery, as the four 1.2 AAA batteries were not providing enough power for the board 5V regulator, which affected the voltage supplied to the steer potentiometer, therefore affecting the analogic read.
The car is being powered with a 9V NIMH battery, as the four 1.2 AAA batteries were not providing enough power for the board 5V regulator, which affected the voltage supplied to the steer potentiometer, therefore affecting the analogic read.
Wednesday, November 3, 2010
steer control - dc motor with potentiometer
The motor shield that was built is now being used to command the steer motor. The base comes with a very small dc motor and a potentiometer. How the original electronic worked with that "servo" was not deeply investigated (what is the rated voltage of the motor?).
The test setup is the motor shield + arduino 2009 + potentiometer + dc motor
The potentiometer is being fed with3v3 5v output from arduino, to have a stable reading. The input goes to an analogic port of arduino and is represented in a scale of 0 to 1023. There is some noise in this readings, around +/- 2 units in the 1024 scale.
note: maybe the maximum reference is still 5v ??
a 3.3v is provided to the outputs of the l293 on the motor shield, by an external power source (in the future this will come from and independent 3v3 regulator, powered by a 3v7 LiPo battery).
the program running at arduino implements a PID control with the aid of the Arduino - PIDLibrary.
The test setup is the motor shield + arduino 2009 + potentiometer + dc motor
The potentiometer is being fed with
note: maybe the maximum reference is still 5v ??
a 3.3v is provided to the outputs of the l293 on the motor shield, by an external power source (in the future this will come from and independent 3v3 regulator, powered by a 3v7 LiPo battery).
the program running at arduino implements a PID control with the aid of the Arduino - PIDLibrary.
Tuesday, November 2, 2010
Friday, October 29, 2010
Final(?) Hardware Specs and Costs
- base: Wholesale rc car Product-10pcs/lot Mclaren model car Remote control toy ~29€ (40 USD)
- mc:Arduino Fio Sparkfun [SF-DEV-09712] - 19,22 €
- batteries: Polymer Lithium Ion Batteries - 1100mAh Sparkfun [SF-PRT-00339] - 6,41 €
- xbee modem: XBee 1mW Wire Antenna Sparkfun [SF-WRL-08665] - 22,43 €
- build hbridge from lab components: ~10€ (l293e = 6.6€)
- steering servo (not sure if necessary): HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo ~2€
putting all together, individual robot cost: ~90€
real costs to lab per robot (excluding xbee modem and hbridge costs): ~57€
EXTRA EQUIPMENT
50% extra batteries:
3+ Polymer Lithium Ion Batteries - 1100mAh [SF-PRT-00339] - 6,41 €
Xbee device to use with the computer:
2x XBee Explorer Dongle [SF-WRL-09819] - 23,07 €
Device to program the arduino:
2x FTDI Basic Breakout - 3.3V [SF-DEV-09873] - 12,82 €
Devices to change the bootloader of arduino (required to wireless program arduino)
1x Pocket AVR Programmer [SF-PGM-09825] - 12,82 €
1x AVR - ICSP Adapter [SF-DEV-09046] - 5,77 €
2x 2x5 AVR ICSP Male Header [SF-PRT-00778] - 0,51 €
Acessories for connections
4x Break Away Female Headers [SF-PRT-00115] - 0,96 €
4x Break Away Headers - Right Angle [SF-PRT-00553] - 0,96 €
4x Break Away Headers - Straight [SF-PRT-00116] - 0,64 €
USB cables to power arduino, recharge batteries, use programmer, use xbee explorer, use avr
4x USB miniB Cable - 6 Foot [SF-CAB-00598] - 2,69 €
- mc:Arduino Fio Sparkfun [SF-DEV-09712] - 19,22 €
- batteries: Polymer Lithium Ion Batteries - 1100mAh Sparkfun [SF-PRT-00339] - 6,41 €
- xbee modem: XBee 1mW Wire Antenna Sparkfun [SF-WRL-08665] - 22,43 €
- build hbridge from lab components: ~10€ (l293e = 6.6€)
- steering servo (not sure if necessary): HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo ~2€
putting all together, individual robot cost: ~90€
real costs to lab per robot (excluding xbee modem and hbridge costs): ~57€
EXTRA EQUIPMENT
50% extra batteries:
3+ Polymer Lithium Ion Batteries - 1100mAh [SF-PRT-00339] - 6,41 €
Xbee device to use with the computer:
2x XBee Explorer Dongle [SF-WRL-09819] - 23,07 €
Device to program the arduino:
2x FTDI Basic Breakout - 3.3V [SF-DEV-09873] - 12,82 €
Devices to change the bootloader of arduino (required to wireless program arduino)
1x Pocket AVR Programmer [SF-PGM-09825] - 12,82 €
1x AVR - ICSP Adapter [SF-DEV-09046] - 5,77 €
2x 2x5 AVR ICSP Male Header [SF-PRT-00778] - 0,51 €
Acessories for connections
4x Break Away Female Headers [SF-PRT-00115] - 0,96 €
4x Break Away Headers - Right Angle [SF-PRT-00553] - 0,96 €
4x Break Away Headers - Straight [SF-PRT-00116] - 0,64 €
USB cables to power arduino, recharge batteries, use programmer, use xbee explorer, use avr
4x USB miniB Cable - 6 Foot [SF-CAB-00598] - 2,69 €
Thursday, October 28, 2010
Wednesday, October 27, 2010
IW02 Test Report
This is the report of the tests conducted with the RC car chassis, to validate the viability of using such solution. The setup was first assembled in a breadboard linking an Arduino Duemilanove, a Xbee Series 2 and an H-Bridge (L293E). Another Xbee modem was connected to a laptop and sent messages to the remote one (in the car).
This first test was successful, with signals sent via wireless to command the traction motor of the car.
The next step was to build an Arduino compatible shield containing the Xbee and the H-Bridge, to finally test the capability of the car to start the motor with a load applied (the car weight). This test also had good results. The car was fully mobile, and several situations were tested.
Unfortunately the batteries soon wore off and the Arduino board could not obtain enough power. Another minor problem found was a lag of wireless messages, although it was not constant.
The next step is to install new batteries and measure the minimum voltage to start moving the car, and also assess if the servo that came with the RC chassis is good enough for our research purposes.
This first test was successful, with signals sent via wireless to command the traction motor of the car.
The next step was to build an Arduino compatible shield containing the Xbee and the H-Bridge, to finally test the capability of the car to start the motor with a load applied (the car weight). This test also had good results. The car was fully mobile, and several situations were tested.
Unfortunately the batteries soon wore off and the Arduino board could not obtain enough power. Another minor problem found was a lag of wireless messages, although it was not constant.
The next step is to install new batteries and measure the minimum voltage to start moving the car, and also assess if the servo that came with the RC chassis is good enough for our research purposes.
Monday, October 25, 2010
Current Costs of Robot Base
Estimated current costs (excluding shipping costs):
-base: ~17€ (26 USD)
-mc: ~17€
-batteries: ~6.5€
-xbee modem: ~25€
total so far: 65.5€
what is missing?
deppending if I manage to use the h-bridge that comes with the base:
- build hbridge from lab components: ~10€ (l293e = 6.6€)
- buy motor driver shield:
--- Adafruit Motor/Stepper/Servo Shield for Arduino kit [v1.0] - the best and cheaper ~ 20.5
--- SparkFun Electronics - Ardumoto - Motor Driver Shield ~ 22€
--- Arduino - ArduinoMotorShield ~ 20.5
the xbee support:
- SparkFun Electronics - XBee Wireless Shield
- SparkFun Electronics - XBee Explorer Regulated ~9€ (may require some hardware modifications, don't change ttl signals level)
- SparkFun Electronics - Breakout Board for XBee Module (must build connections and level changer if to use a 5V board) ~ 4.5€
- XBee adapter - Simple wireless communication ~10€ (regulate power and ttl levels, pinout needs adapter)
- Arduino - ArduinoXbeeShield ~17.5€
steering servo:
- HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo ~ 2€
so, putting all together:
- expensive solution: 105€
- cheap sollution: 82€
-base: ~17€ (26 USD)
-mc: ~17€
-batteries: ~6.5€
-xbee modem: ~25€
total so far: 65.5€
what is missing?
deppending if I manage to use the h-bridge that comes with the base:
- build hbridge from lab components: ~10€ (l293e = 6.6€)
- buy motor driver shield:
--- Adafruit Motor/Stepper/Servo Shield for Arduino kit [v1.0] - the best and cheaper ~ 20.5
--- SparkFun Electronics - Ardumoto - Motor Driver Shield ~ 22€
--- Arduino - ArduinoMotorShield ~ 20.5
the xbee support:
- SparkFun Electronics - XBee Wireless Shield
- SparkFun Electronics - XBee Explorer Regulated ~9€ (may require some hardware modifications, don't change ttl signals level)
- SparkFun Electronics - Breakout Board for XBee Module (must build connections and level changer if to use a 5V board) ~ 4.5€
- XBee adapter - Simple wireless communication ~10€ (regulate power and ttl levels, pinout needs adapter)
- Arduino - ArduinoXbeeShield ~17.5€
steering servo:
- HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo ~ 2€
so, putting all together:
- expensive solution: 105€
- cheap sollution: 82€
Hardware Links II
New hardware specifications for the robot (must create a name)
Base:
1/28 firelap2.0 miniz rc car chassis products, from alibaba.com
Wholesale rc car Product-10pcs/lot Mclaren model car Remote control toy (new website)
Microcontroller:
Arduino Wiki English
Arduino - ArduinoBoardPro (cheaper and cleaner, must decide for whether 3.3V or 5V, this choice may have an implication in the use of arduino compatible shields?)
Wireless:
Arduino - ArduinoXbeeShield (too expensive)
SparkFun Electronics - XBee Explorer Regulated (cheaper and more simple, but may have some design problems: SparkFun Electronics • View topic - XBee Explorer Regulated Bug)
alternatives: XBee adapter - Simple wireless communication or SparkFun Electronics - Breakout Board for XBee Module
Batteries:
RS Cargadores y baterÃas recargables de NiMH, electrónica de consumo
note: for 5 cars = 20 batteries plus 50% to recharge backups, around 30 batteries, plus 2 chargers, or a big one?
Servos (not completely sure if the are necessary):
HobbyKing Online R/C Hobby Store : Turnigy TG9e 9g / 1.5kg / 0.10sec Eco Micro Servo
HobbyKing Online R/C Hobby Store : HXT500 5g / .8kg / .10sec Micro Servo
HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo
Base:
Wholesale rc car Product-10pcs/lot Mclaren model car Remote control toy (new website)
Microcontroller:
Arduino - ArduinoBoardPro (cheaper and cleaner, must decide for whether 3.3V or 5V, this choice may have an implication in the use of arduino compatible shields?)
Wireless:
SparkFun Electronics - XBee Explorer Regulated (cheaper and more simple, but may have some design problems: SparkFun Electronics • View topic - XBee Explorer Regulated Bug)
alternatives: XBee adapter - Simple wireless communication or SparkFun Electronics - Breakout Board for XBee Module
Batteries:
RS Cargadores y baterÃas recargables de NiMH, electrónica de consumo
note: for 5 cars = 20 batteries plus 50% to recharge backups, around 30 batteries, plus 2 chargers, or a big one?
Servos (not completely sure if the are necessary):
HobbyKing Online R/C Hobby Store : Turnigy TG9e 9g / 1.5kg / 0.10sec Eco Micro Servo
HobbyKing Online R/C Hobby Store : HXT500 5g / .8kg / .10sec Micro Servo
HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo
Robot Base
the new website to buy the chassis: Wholesale rc car Product-10pcs/lot Mclaren model car Remote control toy
Sunday, October 24, 2010
Week Review
Effort was mostly spent in validating the base proposal in order to proceed with the purchase process.
The short term goal is to evaluate the traction dc motor from the robot base, by wireless commands sent via xbee. I am afraid that the minimal speed that I could keep the robot moving would be too fast. The test setup:
iw02 base + 4 AAA batteries + arduino + h-bridge + xbee <---> xbee + laptop
I will send speed commands via arduino and evaluate the base movements.
Note: Can I measure the voltage at the motor terminals with arduino?
I will use the xbee modems at AT mode, so one modem will echo commands received from the other (Arduino - ArduinoXbeeShield, XBEE Basics - Community Tutorials).
The next step is to evaluate the steering servo performance, acoording to results, a new servo would have to be bought.
The short term goal is to evaluate the traction dc motor from the robot base, by wireless commands sent via xbee. I am afraid that the minimal speed that I could keep the robot moving would be too fast. The test setup:
iw02 base + 4 AAA batteries + arduino + h-bridge + xbee <---> xbee + laptop
I will send speed commands via arduino and evaluate the base movements.
Note: Can I measure the voltage at the motor terminals with arduino?
I will use the xbee modems at AT mode, so one modem will echo commands received from the other (Arduino - ArduinoXbeeShield, XBEE Basics - Community Tutorials).
The next step is to evaluate the steering servo performance, acoording to results, a new servo would have to be bought.
Saturday, October 23, 2010
Friday, October 22, 2010
Back to Xbee
X-CTU page: Diagnostics, Utilities and MIBs - XCTU - Technical Support - Digi International
How to make X-CTU work in linux: Buck Up Chinny: X-CTU with Linux
Help:
XBEE Basics - Community Tutorials
How to make X-CTU work in linux: Buck Up Chinny: X-CTU with Linux
Help:
XBEE Basics - Community Tutorials
More on motor control with arduino
Shields:
Arduino Motor Shield (L293) (SKU: DRI0001) - Robot Wiki
Lots of arduino related material:
nkc electronics
Arduino Motor Shield (L293) (SKU: DRI0001) - Robot Wiki
Lots of arduino related material:
nkc electronics
Thursday, October 21, 2010
Wednesday, October 20, 2010
Hardware Links
Base:
1/28 firelap2.0 miniz rc car chassis products, from alibaba.com
Servos:
HobbyKing Online R/C Hobby Store : Turnigy TG9e 9g / 1.5kg / 0.10sec Eco Micro Servo
HobbyKing Online R/C Hobby Store : HXT500 5g / .8kg / .10sec Micro Servo
HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo
Microcontroller:
Arduino Wiki English
Wireless:
Arduino - ArduinoXbeeShield
XBee® & XBee-PRO® ZB ZigBee® PRO RF Modules - Digi International
1/28 firelap2.0 miniz rc car chassis products, from alibaba.com
Servos:
HobbyKing Online R/C Hobby Store : Turnigy TG9e 9g / 1.5kg / 0.10sec Eco Micro Servo
HobbyKing Online R/C Hobby Store : HXT500 5g / .8kg / .10sec Micro Servo
HobbyKing Online R/C Hobby Store : HXT900 9g / 1.6kg / .12sec Micro Servo
Microcontroller:
Arduino Wiki English
Wireless:
Arduino - ArduinoXbeeShield
XBee® & XBee-PRO® ZB ZigBee® PRO RF Modules - Digi International
Blog start
Last meeting summary:
3 parallel working fronts:
* state of the art: cooperation and competition
* hardware: servo motors, car bases, xbee
* paper: software, simulator, techniques implementation
TODO:
* buy bases and stepper motors
* xbee libraries
* collision avoidance libraries
* arena modules
* adapt new motors to cars
* test traction motors
* test xbee intercom with developed libs
* ...
3 parallel working fronts:
* state of the art: cooperation and competition
* hardware: servo motors, car bases, xbee
* paper: software, simulator, techniques implementation
TODO:
* buy bases and stepper motors
* xbee libraries
* collision avoidance libraries
* arena modules
* adapt new motors to cars
* test traction motors
* test xbee intercom with developed libs
* ...
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