ar_hardware

Jetson setup & configure

Hardware required

1. Jeston nano
2. Micro SD card
3. USB wifi dongle
4. HDMI cable
5. Mouse
6. Keyboard
7. Jetson power cord

Flash the SD card & boot

https://developer.nvidia.com/embedded/learn/get-started-jetson-nano-devkit#intro

Install requirements & repos

1. Install tabutale & scipy: sudo apt-get install python-tabulate sudo apt-get install python scipy

2. Install arduino IDE from here here. Do not use the 'ubuntu software store' to download.

3. Install teensyduino using instructions here. Don't forget the udev rules, if the recommender cp command doesn't work, just touch the file 49-teensy.rule here: /etc/udev/rules.d/ and copy paste in the text from file on the teensyduino site.

4. Add the Adafruit_MCP4728 library: From the arduino IDE in tools -> manage libraries search for mcp4728 by adafruit + install.

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Teensy Notes

Setup

1. Test functioning Teensy: [https://www.pjrc.com/teensy/first_use.html]

2. Download Teensyduino, Version 1.52 to jetson from: [https://www.pjrc.com/teensy/td_download.html] Follow instructions. Note: Download Arduino 1.8.12/latest tested support. (We need to determine which libraries are needed so we don't install them all for production)

3. Extract arduino dowloaded files. Install Arduino IDE by running ./installArduinoIDE.sh

4. Check Teensey Board is visable in Arduino IDE -> Tools -> Board and select Teensy 4.0

5. Install Teensy loader for command line from source. Follow instructions: [https://www.pjrc.com/teensy/loader_cli.html]

6. Compile test_stepperMotor.ino in ArduinoIDE using Sketch -> Compile. Load onto teesny: Press load button on teensy (need to use command line for this later using teensy_loader_cli). When uploading via the command line make sure the programming symbol adn then the reboot symbol appear on the teensy gui. If you find that upload is stalling check the usb connection to the usb and replug/reset if needed. Pressing the manual upload button on the teensy is a workaround but try to fix the usb connection as this can cause serial communication problems when you launch the ROS. Make sure usb cable is securely connected to nano, replace/swap usb cableif you suspect it's faulty.

7. Setup port for teensy in ArudinoIDE Tools -> Port, select Teensy. Tools -> Serial Monitor, outputs console of teensy programs. Good way to check program is running correctly on teensy.

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Setup for ROS msgs over Teensy

1. Install ROS serial communication package for arduino. For more details o the isntall commands below see: [http://wiki.ros.org/rosserial_arduino/Tutorials/Arduino%20IDE%20Setup]

To install ROS serial pkgs run the following commands: sudo apt-get install ros-melodic-rosserial-arduino

AND: rosserial_client rosserial_embeddedlinux rosserial_mbed rosserial_msgs rosserial_python rosserial_server rosserial_test

sudo apt-get install ros-melodic-rosserial

To install necccesarry ros libarires in the arduino environment run the following commands: cd Arduino/libraries rosrun rosserial_arduino make_libraries.py .

To check install: Restart ArduinoIDE -> File -> Examples -> ros_lib -> Hello_world

2. Add teensy 4.0 serial functionality to line 44 in Arduino/libraries/ros_lib/ArduinoHardware.h . See [pjrc.com/teensy/loader_cli.html] for more info on the names of each MCU/teensy X.X .

Code to append: defined(__IMXRT1062__)

Line 44 should now look like: #if defined(__MK20DX128__) || defined(__MK20DX256__) || defined(__MK64FX512__) || defined(__MK66FX1M0__) || defined(__MKL26Z64__) || defined(__IMXRT1062__)

3. Add custom AR messages to arduino ros_lib: http://wiki.ros.org/rosserial_arduino/Tutorials/Adding%20Custom%20Messages, using this command

rosrun rosserial_arduino make_libraries.py /home/ben/Arduino/libraries /home/ben/catkin_ws/src/ar_commander/msg

NOTE: Always delete the existing ros_lib folder in ~/Arduino/libraries before rebuilding headers for msgs otherwise no updates will be made.

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Creating connection over usb between teensy node and ros master on jetson

1. Check baud rate on teensy - default is 57600. If baud rate is too high can cause comms issues. Start with 57600 can go higher later and test. Load script onto teensy with teens_loader.

2. Check teensy port on AarduinoIDe -> Tools -> Port. Check that the port exists: ls /dev/ttyACM0. Check port has read and write permissions: sudo chmod 777 /dev/ttyACM0

3. (a) Make changes to SerialClient.py as per issue at: https://analyticalrobotics.atlassian.net/browse/AR1-40

4. (b) Compile arduino file using load script: ./load_arduino_file.sh motor_interface.ino

5. (c) After launching ros master run: rosrun rosserial_python serial_node.py _port:=/dev/ttyACM0 _baud:=57600

make sure the correct port and baud rate is used. If connection succesful will see this: INFO [1593459264.359302]: ROS Serial Python Node INFO [1593459264.368955]: Connecting to /dev/ttyACM0 at 57600 baud INFO [1593459266.475355]: Requesting topics... INFO [1593459269.612953]: Note: subscribe buffer size is 2048 bytes INFO [1593459269.616665]: Setup subscriber on controller_cmds [ar_commander/ControllerCmd]

4. Test with controller msg: rostopic pub -r 10 /controller_cmds ar_commander/ControllerCmd "{velocity_arr:ta: [0,0,0,0]}, phi_arr: {data:[1.5, 1.5, 1.5, 1.5]}}"

5. Check that the teensy is receiving the messages by monitoring the /chatter (may need to add this manually to hardware_interface.ino) topic which is published within the controller_cmds callback from the teensy. See Teensy Setup Notes for more debug info on this.

Debugging notes:

A. Make sure you have serial monitor closed and no serial print lines in your code. Cant use both the serial usb and serial monitor at the same time. If you do you'll get this error: "Unable to sync with device; possible link problem or link software version mismatch such as hydro rosserial_python with groovy Arduino"

B. Make sure the buffer size is big enough for a backlog of your msgs:

ros::NodeHandle_<HardwareType, MAX_PUBLISHERS=25, MAX_SUBSCRIBERS=25, IN_BUFFER_SIZE=512, OUT_BUFFER_SIZE=512> nh;

More info: http://wiki.ros.org/rosserial/Overview/Initialization

C. Unplug and replug teensy to clear port if needed (last resort)

D. Compile code and reboot teensy

E. Increase time out if error is "lost sync..." see: https://analyticalrobotics.atlassian.net/browse/AR1-39

F. Check that correct ports are being called for the teensy and other decawave boards see localization notes.

G. check sum error or wrong msg id. 1) Check that the msg is updated and built correctly for the msg version in ar_commander in ~/Arduio/libbraries/ros_lib remake if not see teensy msg setup for details. 2) Check that the hardware interface is accessed the msg in the correct format. 3) Check you are njot overflowing the buffer by publishing in the loop/over publishing.

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Decawave dev board setup:

1. Download J-Link Software and Documentation pack here

2. Download the firmware image and all the documentation and install android app here

3. Flash the boards with the firmware image from above using j-flash lite and following the instructions on page 14 of the DWM1001 Firmware User Guide -Version 1.0 from 2017. Note: this is different to the firmware API guide.

4. Connect to boards using android app add the boards to a network & follow instructions to configure as anchor or tag. Set one of the anchors to be the initiator. Set the location of the anchors.

5. Increase the update rate for the tags to 10Hz (highest allowed) for normal and stationary. Set UWB to active.

6. When installing on robot, after robot startup plug in to usb from the board on the Y arm of the robot, then plug in the board on the X arm. This ensures that the address used by the board on the Y arm is ttyACM1 and the X arm uses ttyACM2. This will allow our decawave interface to use the boards correctly.

To interface using minicom:

1. Download minicom using sudo apt-get install minicom.

2. To connect to a board over USB, make sure that the correct port is being opened. To check this, before plugging the board in, use dmesg | grep tty. Then plug in the board and use dmesg | grep tty again. There should be a new entry that looks something like ttyACM0, where the last number may be different.

3. Use sudo minicom -D /dev/ttyACM0 using the correct port found above in place of ttyACM0. Welcome to minicom screen should show up.

4. Press enter/return on the keyboard twice within 1 second to enter shell mode. If the port is correct and the USB cable is good and the firmware is good, you should see DWM1001 TWR Real Time Location System, and dwm>. Type ? followed by enter to see possible commands.

Debugging notes:

A. Check port numbers are correct for each usb connection - NB. Decawave/teensy will appear to hang but is trying to send signals acorrs the wrong port or a decawave port. Decawaves may also be trying to send signals to a "teensy" port. Check the ports using dmesg | grep tty while removing/plugging in usbs. It appears that port numbering is selected at startup and once first inserted and doesnt change if you unplug after that.

B. Anytime you connect to the board via USB make sure you use a good, reliable data cable or you will have a bad time.

C. The boards should all be perpendicular to the ground, ie. the antenna should be the furthest point from the ground. If the boards are horizontal they won't be able to communicate properly.

D. If the update rate of the tag isn't at 10Hz (highest) there will be issues with delayed info. This should be done from the android app or using minicom.

E. Make sure that the position of the anchors is as accurate as possible or the location engine will be very unreliable or will just constantly fail. This can be entered using the android app or using mnicom. The auto positioning feature in the app can be used, however clear lines of sight between boards is a must for the auto positioning to work properly - follow instructions on the app.

NOTE: Drive folder with documentation.

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Setup Time-Of-Flight (TOF) sensors - VL53L1X

1. Setup wiring of multiple TOFs as in wiring digram (here)[/home/ben/Arduino/test_TOF]. Note use 3.3V source, some articles suggest 5V but that didnt work.

2. Install VL53L1X arduino package: ArduinoIDE -> Sketch -> Include Libraries -> Manage Libraries -> VL53L1X.

3. Upload the catkin_ws/src/ar_hardware/scripts/tof_tests/test_TOF3 script to the teensy: ./load_arduino_file.sh test_TOF3_VL53L1X.ino and view serial monitor to check outputted distances.

NOTE: VL53L1X docs and library.

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AMT21 encoder setup:

1. Download and run AMT viewpoint here. (Windows only).

2. Connect to encoder using usb adapter.

3. Set desired address using GUI (default is 0x54). The addresses used by our hardware interface are 0x4C, 0x50, 0x54, 0x58. These correspond to 76, 80, 84, 88 in decimal and L, P, T, X. These correspond to wheel position: furthest from centre on the Y-arm, closest to centre Y-arm, closest to centre X-arm, furthest from centre X-arm.

4. Install encoder onto motor shaft as per instructions here from CUI website.

5. Connect RS485 board to teensy.

6. Connect the encoders to the RS485 bus A to A and B to B using schematic from datasheet.

7. Align the wheels to the desired 0 position with the encoders attatched. Run the encoderReset.ino program on the teensy to set the encoder 0 position. This will persist after shutdown.

NOTE: AMT21 encoder datasheet.

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Stepper Motors & Drivers

1. NOTE: For stepper motors adjust voltage across motor driver, DRV8825: see video at this link: https://youtu.be/89BHS9hfSUk, more info on DRV8825: [https://www.pololu.com/product/2133]. Aim for 0.5V or less (rotation appears smoothest at 0.35V)