Making Robots with mruby at Rubykaigi2015(en)

1. Making Robots
with mruby
2015-12-12 RubyKaigi 2015
Yurie Yamane
Team Yamanekko

2. Who am I?
やまね ゆりえ(Yurie Yamane)
@yuri_at_earth(only in Japanese)
a member of TOPPERS project
ET robocon staff
たいやき部(taiyaki-bu)

3. Yamanekko
https://github.com/yamanekko

4. 2012

5. 2013

6. 2014
nomitory

7. 2015

8. Robots
and Us

9. http://global.yamaha-motor.com/jp/showroom/event/2015tokyomotorshow/sp/exhibitionmodels/mgp/
“There are probably some things in this world that only I can do.”
https://www.youtube.com/watch?v=EzgJWwAx8Mo

10. PART 1:
Self-
balancing
Robot
using
LEGO EV3

11. 闇RubyKaigi(2011)
http://gihyo.jp/news/report/01/rubykaigi2011/0001?page=7

12. http://www.etrobo.jp/2015/

13. ETロボコンAdvent Calendar 2015
http://www.adventar.org/calendars/734

14. ET Robot Contest
• aka ET ロボコン(ET ROBOCON)
• ET means “Embedded Technology”
• To develop the advanced skills of
embedded technology such as modeling,
designing, and developing embedded
systems
• “one-make racing” style (all robots have
same designs)

15. EV3way: Software
System OS Language
TOPPERS/EV3RT TOPPERS RTOS C, C++
MonoBrick Linux C#
leJOS EV3 Linux Java

16. EV3way: Software
• mruby on EV3RT + TECS
• mrby Forum ver.
• yamanekko ver.
System OS Language
TOPPERS/EV3RT TOPPERS RTOS C + mruby

17. mruby-ev3rt

18. mruby-ev3rt demo
Sep. 20th, 2015 at Fukuyama, Hiroshima Pref.
Movie by A. Hirai with ET Robocon Staff@chu-shikoku

19. • TOPPERS（Toyohashi OPen Platform for
Embedded Real-time Systems）
• TOPPERS’ Products
• Realtime Kernel
• Automotive Kernel
• Tools
• TOPPERS + TSUBAME(swallow) -> TOPAME
TOPPERS Project
とぱめ(TOPAME)
https://www.toppers.jp/

20. Who uses TOPPERS?
http://ev.nissan.co.jp/LEAF/?pfa=01
http://www.ricoh.co.jp/printer/sg/3100ke/
http://www.korg.com/jp/products/dj/electribe/
http://music.casio.com/ja/products/digital_pianos/ghs/products/
https://en.wikipedia.org/wiki/H-IIB
from: http://toppers.jp/applications.html

21. TOPPERS Kernel Roadmap
ATK1 ATK2 ATK3
FMP3
HRP3
ASP3
2000 2010 2020
1st generation 3rd generation2nd generation
ITRON
Automotive
FDMP
HRP
FI4
JSP
Dynamic
gen.
ASP Safety
HRP2
FMP
ASP
SSP
http://toppers.jp/docs/intro-invite.pdf

22. TOPPERS EV3RT
unprivileged
mode
(user mode)
privileged
mode
(kernel mode)
http://dev.toppers.jp/trac_user/ev3pf/wiki/WhatsEV3RT

23. Self Balancing Robot

24. Inverted Pendulum

25. Inverted Pendulum

26. Inverted Pendulum

27. Inverted Pendulum

28. Inverted Pendulum

29. Inverted Pendulum

30. Inverted Pendulum

31. How Robot Works
Target Board
Sensors
Actuator

32. Gyro Sensor
Ultrasonic Sensor
Motor
Light Sensor

33. How Robot Works
Target Board
Sensors
Actuator
Read

34. How Robot Works
Target Board
Sensors
Actuator
Move

35. How Robot Works
sense
calculate
control motor
execute
periodically

36. What’s RTOS
• OS for Real Time System
• Real time system: to make much of Deadlines
• NOTICE: “Real-Time” has several meanings
• “Real-Time” in RTOS is completely different
from such as “Real-time Web”

37. Time is Resource
• In real time
system, Tasks
should be done
in a given time
(deadline)
• RTOS manage
“Time” as
resources (like
memories)
https://www.flickr.com/photos/arjanrichter/3886579525/

38. Priority of tasks
• Every tasks have their own priority
• Lower-priority tasks never execute
when higher-priority tasks alive
• While higher-priority task is running,
lower-priority tasks are not running
(into READY status)

39. All tasks are mruby
main_task
balance_task
watch_task
HIGH priority
LOW priority
balancer.rb
watch.rb
app_ruby.rb
注）バランス制御に重点を置いた例。
これが正しい方法というわけではない

40. balancer.rb
loop do
forward = 30
color = colorSensor.brightness
if color >= (LIGHT_WHITE + LIGHT_BLACK)/2
turn = 20 ## turn left
else
turn = -20 ## turn right
end
pwm_left, pwm_right, *args =
balancer.calculate_auto(forward, turn, GYRO_OFFSET)
leftMotor.pwm = pwm_left
rightMotor.pwm = pwm_right
EV3RT::Task.sleep
end

41. watch.rb
loop do
break if back_button.pressed?
EV3RT::Task.sleep
end

42. app_ruby.rb
## initialize sensors, motors, clock and tasks
touchSensor = EV3RT::TouchSensor.new(EV3RT::PORT_1)
gyroSensor = EV3RT::GyroSensor.new(EV3RT::PORT_4)
leftMotor = EV3RT::Motor.new(EV3RT::PORT_C, EV3RT::LARGE_MOTOR)
rightMotor = EV3RT::Motor.new(EV3RT::PORT_B, EV3RT::LARGE_MOTOR)
clock = EV3RT::Clock.new()
EV3RT::Task.active(EV3RT::BALANCE_TASK_ID) ## initialize balancer
loop do ## waiting button pushed
break if touchSensor.pressed?
clock.sleep(10)
end
EV3RT::Task.start_cyclic(EV3RT::BALANCE_CYC_ID) ## start balancer
EV3RT::Task.sleep ## do other tasks

43. Classes in mruby-ev3rt
Motor
TailMotor
Sensor
GyroSensorColorSensor
TouchSensor
LED LCD Clock Serial Task
Balancer
Button

44. PART 2:
DIY
Self-
balancing
Robot

45. DIY Self-balancing Robot
Can we make our own robots
from scratch?
https://www.flickr.com/photos/84906483@N08/8747337118/

46. DIY Self-balancing Robot
😿🙀😸
http://www.instructables.com/id/Another-Easier-Inverted-Pendulum/

48. Collecting Parts
Target Board
Sensors Actuator

49. Raspberry Pi A+
• Lower battery usage
than Pi B+ and Pi 2
• Works with small
USB battery
• Cheeper (< $30) than
Pi B+ and Pi 2

50. Raspberry Pi A+
😿

51. ARM Family
http://www.emcu.it/CortexFamily/CortexFamily.html
Pi1 Pi2
EV3
STM32F4

52. Inverted Pendulum

53. How to measure an angle

54. Gyro Sensor
http://akizukidenshi.com/catalog/g/gK-06779/

55. Gyro Sensor
• ST Micro L3GD20
• 3-axis digital
gyroscope
• use 8 pin DIP module
by Akizuki Denshi

56. Gyro Sensor
😿

57. Gyro Sensor
🙀

58. Measuring the Angle
!1 !2

60. How to rotate wheels

61. DC Motor
• TAMIYA FA-130 Motor
• speed control by voltage
• IO cannot change voltage
• 3.3 V (fixed)
• → use PWM

62. DC Motor
😿

64. (Motor + Gear) x 2

66. Wheel x 2

67. Body
Tamiya 70157 Universal Plate Set

69. Batteries (for motors)

70. Batteries (for motors)
🙀

71. Battery (for Pi A+)

73. connect a sensor
?

74. SPI vs I2C
• SPI and I2C are popular protocols
• Gyro sensor L3GD20 supports both
• SPI is more complex, but faster than
I2C
• Raspberry Pi supports SPI (see
“BCM2835 ARM Peripherals”)
• https://www.raspberrypi.org/wp-content/uploads/
2012/02/BCM2835-ARM-Peripherals.pdf

75. Serial Peripheral Interface (SPI)
• Master and Slave model
• In our case, Raspberry Pi is master
• 4 pins (Input, Output, Clock, Select)

76. Demo

77. Gyro Test
serial = Serial.new
timer = SystemTimer.new
gyro = Gyro.new()
serial.puts("time,gyro")
MESURE_COUNTS = 45
start_time = timer.now
cnt = 0
loop do
mesure_sum = 0
MESURE_COUNTS.times{ mesure_sum += gyro.read(Gyro::Y) }
omega_i = mesure_sum * 0.00875 / MESURE_COUNTS;
cnt +=1
now = ((timer.now - start_time) / 1000).floor
if cnt == 10
cnt = 0
serial.puts("#{now},#{omega_i}")
end
end

78. connect motors
?

79. PWM
• Pulse-Width Modulation
• pseudo-analog signal output
http://www.electronics-tutorials.ws/blog/pulse-width-modulation.html

80. PWM
• Raspberry Pi A+/B+/2 supports 2 PWMs
• Old Raspberry Pi B support only 1
PWM
• So we can control 2 motors (Right/Left)

81. Motor Driver
ST Micro L298N

82. Motor Driver
PWMIN1 IN2
OUT1
OUT2
MOTOR
Motor Driver
Raspberry Pi
IN1 IN2 OUT
0 0 STOP
0 1 Forward
1 0 Reverse
1 1 Brake

83. Demo

84. Motor Test
# in1, in2, enable, pwm0or1
motor_left = Motor.new(5,6,12,0)
motor_right = Motor.new(16,20,19,1)
motor_right.drive(50)
motor_left.drive(50)
RSRobot.delay(3000000)
motor_left.drive(200)
motor_right.drive(200)
RSRobot.delay(3000000)
motor_right.drive(50)
motor_left.drive(50)
RSRobot.delay(3000000)
motor_right.drive(-100)
motor_left.drive(-100)
RSRobot.delay(3000000)
motoy_right.stop
motor_left.sop

85. JTAG
• For Debugger
• Doesn’t have to
use it
• but with JTAG, we
can use GDB, so
it’s very helpful to
debug

86. Pinout

87. Making
Balancer
class

88. Balancing Equation
power = k_1 * (Angular Velocity) +
k_2 * (Angle) +
k_3 * (Velocity) +
k_4 * (Position)
P = K!! + K✓✓ + Kvv + Kxx

89. Angle
✓ ✓

90. Angular Velocity
! !(fast) (slow)

91. Velocity
(fast) (slow)vv

92. Position
(far) (near)y asixsy asixs

93. Balancing Equation
power = k_1 * omega_i +
k_2 * theta_i +
k_3 * v_i +
k_4 * x_i
P = K!! + K✓✓ + Kvv + Kxx

94. Balancing Equation
power = k_1 * omega_i +
k_2 * theta_i +
k_3 * v_i +
k_4 * x_i
a ≒ Power
v ≒ ∫ Power
x ≒ ∬ Power
P = K!! + K✓✓ + Kvv + Kxx

95. Balancing Equation
P = K!! + K✓✓ + Kvv + Kxx
= K!! + K✓
X
! + Kv
X
P + Kx
X X
P
power = k_1 * omega_i +
k_2 * theta_i +
k_3 * v_i +
k_4 * x_i
a ≒ Power
v ≒ ∫ Power
x ≒ ∬ Power

96. Balancing Equation
theta_i += omega_i
v_i += power
x_i += v_i
power = k_1 * theta_i +
k_2 * omega_i +
k_3 * v_i +
k_4 * x_i
P = K!! + K✓✓ + Kvv + Kxx
= K!! + K✓
X
! + Kv
X
P + Kx
X X
P

97. Balancer class
class Balancer
def calculate(omega_i)
@theta_i += omega_i
# …
t = @k_angle * @theta_i
o = @k_omega * omega_i
# …
power = t + o + …
# …
return power, power
end
end

98. main loop
loop do
gyro_value = gyro.measure(Gyro::Y,
MESURE_COUNTS)
pwm_left, pwm_right =
balancer.calculate(gyro_value)
motor_left.pwm = pwm_left
motor_right.pwm = pwm_right
end

99. demo

101. まずは何か作ってみよう！

102. Source code
•https://github.com/yamanekko/mruby-ev3rt
•https://github.com/yamanekko/mruby-rs-robot
•https://github.com/yamanekko/raspi_robot

103. Thank you & Domo Arigato!
ZZZ...
You can contact us on Twitter: @yuri_at_earth
Special Thanks to: @tenderlove
A. Hirai with ET Robocon Staff@chu-shikoku