aseba - open-source low-level robot programming open-source low-level robot programming st ephane...

ASEBAOpen-Source Low-Level Robot Programming

Stephane Magnenat 1

stephane at magnenat.net

Philippe Retornaz 2

1Autonomous Systems LabETH Zurich

2Mobots group - Laboratory of robotics SystemsEPFL

February 5, 2012

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http://stephane.magnenat.net

http://asl.ethz.ch

http://www.ethz.ch

http://mobots.epfl.ch

http://www.epfl.ch

Outline

Motivation

Current Use

Technical Description

Performances

Wrap-up

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Outline

Motivation

Current Use


Performances

Wrap-up

3 / 46

Motivation: Multi-Microcontrollers Robots

17cm

Modern integrated mobile robotshave

I lots of degrees of freedom

I many and various sensors

Their computing infrastructureconsists of

I a main processor running Linux(ex. Gumstix)

I multiple microcontrollers

I a common communication bus(ex. I2C or CAN)

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Motivation: Usual Approach is Centralized Polling...

microcontroller 1

microcontroller 2

microcontroller 3

processormain

1

cycle cycle

1

activitybus

main processor

continuously

I read sensors

I process data

I set actuators

microcontrollers

I interface tophysical devices

bus

I I2C

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Motivation: ...but Distributed Events are Better!

microcontroller 1

microcontroller 2

microcontroller 3

processormain

2 3

activitybus

main processor

I react to events

I send events

microcontrollers

I interface tophysical devices

I preprocess data

I send events

I react to events

bus

I CAN

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Motivation: An Example of Distributed Events

left motor

right motor

proximity

sensors

tim

e

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no obstacle

left motor

right motor

proximity

sensors

tim

e

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no obstacle

left motor

right motor

proximity

sensors

tim

eobstacle detected

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no obstacle

left motor

right motor

proximity

sensors

tim

eobstacle detected

no obstacle

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Motivation: How to Implement Distributed Events?

I Contrary to centralized polling, with events the emissionpolicy must be distributed as well.

I Microcontrollers must take decisions about what event tosend when, and how to link incoming events to actuators.

I Therefore they must be programmable, but flashing is slow.

I A virtual machine is the solution...

I And so Aseba was born!

I Aseba stands for Actuator and Sensor Event-BasedArchitecture.

I Aseba puts virtual machines inside microcontrollers; enablingtheir programming through a user-friendly language and IDE.

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Motivation: How to Implement Distributed Events?

I Contrary to centralized polling, with events the emissionpolicy must be distributed as well.

I Microcontrollers must take decisions about what event tosend when, and how to link incoming events to actuators.

I Therefore they must be programmable, but flashing is slow.

I A virtual machine is the solution...

I And so Aseba was born!

I Aseba stands for Actuator and Sensor Event-BasedArchitecture.

I Aseba puts virtual machines inside microcontrollers; enablingtheir programming through a user-friendly language and IDE.

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Outline

Motivation

Current Use


Performances

Wrap-up

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Swarm Robotics: hand-bot

6 Aseba VM, real-time unwind control, grasping,and state machines implemented in Aseba

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Swarm Robotics: hand-bot

hand-bot video athttp://www.youtube.com/watch?v=92bLgE6DO2g

In this video, the hand-bot climbs a shelf and retrieves a booksolely using Aseba.

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http://www.youtube.com/watch?v=92bLgE6DO2g

Autonomous Construction: Lonelybuilder

5 Aseba VM, state machines coded in Asebalocalisation, mapping, planning running on Linux ARM

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Autonomous Construction: Lonelybuilder

Lonelybuilder video athttp://www.youtube.com/watch?v=h865RHbT9Ms

In this video, Lonelybuilder constructs a tower by manipulatingcubes. The manipulation state machines are implemented with

Aseba.

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http://www.youtube.com/watch?v=h865RHbT9Ms

Brick for Building Robot: Smartrob

I 2 motor and 8 servo drivers

I 8 infrared-sensor drivers

I additional I/O and A/D

I CAN bus, stackable

I single 3 to 25 V input

I shipped with Aseba

I ROS and D-Bus integration

I soon available for buying

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Educational Robotics: Thymio II

Full-featured open-hardware programmable mobile robot for100 CHF (≈ 80¿), see http://aseba.wikidot.com/en:thymio

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http://aseba.wikidot.com/en:thymio


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1

1

2

2

3

3

4

4

D D

C C

B B

A A

2 Laboratoire de Systèmes Robootiques

Michael BonaniSTI-IMT-LSRO1EPFLCH-1015 LAUSANNE

9A

16.06.201113:33:03

microcontroleur.SchDoc

Date:

Revision:Page de

Thymio2

Project

File :

thymio2-main.PrjPCBPart

PCB principal

VCC

C36100nF

VCC

GND

C37100nF

VCC

GND

C38100nF

VCC

GND

R10110K

VCC

C35100nF

VCC

GND

123456

X1

Con1x6

GND

PGDPGC

PGDPGC

X5R

C3410uF X5R

C39100nF

VCC

GND

VCC

GND

VCC

GND

ACC_INT

ACC_SCKACC_SDA

123456

X2

Con1x6

GND

Buton1Buton2Buton3Buton4Buton5

IR-sens-front2

IR-sens-front3

IR-sens-front4

IR-sens-front5

IR-sens-front1

IR-sens-groundRIR-sens-groundL

IR-pulse-front

IR-pulse-groundL

IR-pulse-groundR

IR-pulse-back

IR-sens-backL

IR-sens-backR

MOTOR1-PWMH1

MOTOR1-PWMH2

MOTOR1-PWML1

MOTOR1-PWML2

MOTOR2-PWMH1MOTOR2-PWMH2

MOTOR2-PWML1MOTOR2-PWML2

MOTOR1-SENSMOTOR2-SENS

D-D+

USB-500

VAenableR1034.7KR104

4.7K

VCC

LED_CLK

LED_CS

LED_SDI

12Y1

815-ABLS-8-B2C4118pF

C4218pF

GND GND

USB-Charge

OUT 1

VSS 3

GND 236 kHz

U20

IRM-3636T

R105100

AGND

36 kHz IR receiver

IR_Receiver

VA

IR_Receiver

Micro

C33100nF

SOUND_OUTSDcard-CS

SDcard-DISDcard-CK

SDcard-DO

C434.7uF

USB-Present

R10210K

C62100nF

t° RT1NCP15XH103F03RC

GND

INNTC2

INNTC2

Therm. NTC Sensor

R137

180

GND S

S2SW-PB

GND

PMD5/CN63/RE5 1

PMD6/SCL3/CN64/RE6 2

PMD7/SDA3/CN65/RE7 3

PMA5/RP21/C1IND/CN8/RG64

RP26/PMA4/C1INC/CN9/RG75

PMA3/RP19/C2IND/CN10/RG86

MCLR7

RP27/PMA2/C2INC/CN11/RG98

VSS9

VDD10

PGEC3/RP18/VBUSON/C1INA/AN5/CN7/RB5 11PGED3/RP28/USBOEN/C1INB/AN4/CN6/RB4 12VPIO/C2INA/AN3/CN5/RB3 13VMIO/RP13/C2INB/AN2/CN4/RB2 14PGEC1/RP1/VREF-/AN1/CN3/RB1 15PGED1/RP0/PMA6/VREF+/AN0/CN2/RB0 16

PGEC2/AN6/RP6/CN24/RB6 17

PGED2/RCV/RP7/AN7/CN25/RB7 18

AVDD19

AVSS20

RP8/AN8/CN26/RB8 21

PMA7/RP9/AN9/CN27/RB9 22

TMS/PMA13/AN10/CVREF/CN28/RB10 23

TDO/AN11/PMA12/CN29/RB11 24

VSS25

VDD26

TCK/PMA11/AN12/CTED2/CN30/RB12 27

TDI/PMA10/AN13/CTED1/CN31/RB13 28

CTPLS/RP14/PMA1/AN14/CN32/RB14 29

RP29/PMA0/AN15/REFO/CN12/RB15 30

PMA9/RP10/SDA2/CN17/RF431

PMA8/RP17/SCL2/CN18/RF532

RP16/USBID/CN71/RF333

VBUS34

VUSB35

D-/RG336 D+/RG237

VDD38

OSCI/CLKI/CN23/RC12 39

OSCO/CLKO/CN22/RC15 40

VSS41

RP2/DMLN/RTCC/CN53/RD8 42

RP4/DPLN/SDA1/CN54/RD9 43

RP3/SCL1/PMCS2/CN55/RD10 44

RP12/PMCS1/CN56/RD11 45

RP11/DMH/CN49/INT0/RD0 46

SOSCI/C3IND/CN1/RC13 47

RPI37/SOSCO/C3INC/TICK/CN0/RC14 48

RP24/VCPCON/CN50/RD1 49

DPH/RP23/CN51/RD2 50

RP22/PMBE/CN52/RD3 51

PMWR/RP25/CN13/RD4 52

PMRD/RP20/CN14/RD5 53

C3INB/CN15/RD6 54

C3INA/CN16/RD7 55

VCAP/VDDCORE56

ENVREG57

VBUSST/VCMPST1/CN68/RF058

VCMPST2/CN69/RF159

PMD0/CN58/RE0 60

PMD1/CN59/RE1 61

PMD2/CN60/RE2 62

PMD3/CN61/RE3 63

PMD4/CN62/RE4 64

U19

PIC24FJ128GB106-I/PT

R143

100K

PIC3301

PIC3302COC33

PIC3401

PIC3402COC34

PIC3501

PIC3502COC35 PIC3601




PIC3902

COC39

PIC4101


PIC4202COC42

PIC4301

PIC4302COC43

PIC6201

PIC6202COC62

PIR10101

PIR10102COR101

PIR10201

PIR10202COR102

PIR10301

PIR10302COR103

PIR10401

PIR10402COR104

PIR10501

PIR10502COR105

PIR13701 PIR13702

COR137

PIR14301PIR14302

COR143

PIRT101

PIRT102

CORT1

PIS201

PIS202

PIS20S

COS2

PIU1901PIU1902

PIU1903

PIU1904

PIU1905PIU1906

PIU1907

PIU1908

PIU1909

PIU19010

PIU19011

PIU19012

PIU19013

PIU19014

PIU19015

PIU19016

PIU19017

PIU19018

PIU19019

PIU19020

PIU19021

PIU19022

PIU19023

PIU19024

PIU19025

PIU19026

PIU19027

PIU19028

PIU19029

PIU19030

PIU19031

PIU19032

PIU19033

PIU19034

PIU19035

PIU19036

PIU19037

PIU19038

PIU19039

PIU19040

PIU19041

PIU19042

PIU19043

PIU19044

PIU19045

PIU19046

PIU19047

PIU19048

PIU19049

PIU19050

PIU19051

PIU19052

PIU19053

PIU19054

PIU19055

PIU19056

PIU19057

PIU19058

PIU19059

PIU19060

PIU19061

PIU19062

PIU19063

PIU19064

COU19

PIU2001

PIU2002

PIU2003

COU20

PIX101

PIX102

PIX103

PIX104

PIX105

PIX106

COX1

PIX201

PIX202

PIX203

PIX204PIX205

PIX206

COX2

PIY101PIY102

COY1

POACC0INT

POACC0SCKPOACC0SDA

POD0

POIR0PULSE0BACK

POIR0PULSE0FRONT

POIR0PULSE0GROUNDL

POIR0PULSE0GROUNDR

POIR0SENS0BACKL

POIR0SENS0BACKR

POIR0SENS0FRONT1

POIR0SENS0FRONT2

POIR0SENS0FRONT3

POIR0SENS0FRONT4

POIR0SENS0FRONT5

POIR0SENS0GROUNDLPOIR0SENS0GROUNDR

POLED0CLK

POLED0CS

POLED0SDI

POMICRO

POMOTOR10PWMH1

POMOTOR10PWMH2

POMOTOR10PWML1

POMOTOR10PWML2

POMOTOR10SENS

POMOTOR20PWMH1POMOTOR20PWMH2

POMOTOR20PWML1POMOTOR20PWML2

POMOTOR20SENS

POSDCARD0CK

POSDCARD0CS

POSDCARD0DIPOSDCARD0DO

POSOUND0OUT

POUSB0500POUSB0CHARGE

POUSB0PRESENT

POVAENABLE

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Li-Po battery level

speaker

microphone

infrared remote controlreceiver

3 axis accelerometer

5 proximity sensors(obstacle detection)’

2 ground sensors(line following)

39 LED to visualizesensors and interaction

reset button

5 capacitive touchbuttons with activity display, and ON-OFF function

pencil support

USB connection(programming and recharging)

memory card slot

hook for trailer

2 proximity sensors

mechanic fixation

2 wheels withspeed control

temperature sensor

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Enables children to discover programming with a mobile robot.

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Simulated Robotics: Challenge

beamer

arena

computer

child computer

development env.

+ local arena

child computer

development env.

+ local arena

child computer

development env.

+ local arena

child computer

development env.

+ local arena

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Outline

Motivation

Current Use


Performances

Wrap-up

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Technical Overview

Aseba:

I allows fast prototyping of the behaviour of microcontrollersconnected through a network,

I provides an IDE for edition, debugging and inspection of thevalues of variables (including sensor and actuators),

I compiles scripts into bytecode,

I executes bytecode on microcontrollers in a virtual machine,

I safe execution,

I dynamic enumeration of microcontrollers’ variables, nativefunctions and events,

I dynamic reprogramming of the microcontrollers,

I asynchronous code execution upon events,

I open source, LGPL.

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Software Architecture

microcontroller

microcontroller

microcontroller

central embeddedcomputer running Linux

desktopcomputer

high-level controlprograms

software switchIDE

optional optional

CANTCP

ROS or D-Bus or TCP • • •

robot

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Microcontrollers

programspecific

application

microcontroller

communicationvirtual machine

shared communication bus

actuatorssensors

low-level control

native functions

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Virtual Machine

I targets 16-bit microcontrollers and better,

I stack based, 16-bit integers,

I executes bytecode(4-bit opcode, 12-bit payload + optional trailing 16-bit words)

I ≈ 1000 lines of C, including debugging logic,

I RAM: 22 bytes + user defined amount of bytecode, variable,stack, and breakpoints.

I flash: 7.5 kB flash (dsPIC30, e-puck),

I no external library requirement, excepted the implementationof bus communication.

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Language

Simple imperative scripting language, octave-like syntax.

I blocks of code executed upon events,

I 16-bit integer variables and arrays,

I common mathematical expressions and arrays access,

I if and when conditionals,

I while and for loops,

I native functions for complex processing,

I subroutines.

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Studio (IDE)

Live Demonstration using Thymio II

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Outline

Motivation

Current Use


Performances

Wrap-up

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Evaluation Platform

Evaluation conducted using the marXbot base.

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Aseba vs Polling: Bus Bandwidth

emp

ty

box

es

wal

ls

empty boxes walls 10 Hz 25 Hz 67 Hz

data

tran

smitt

ed fo

r 1

min

ute

100 B

1 kB

10 kB

100 kB

1 MB

event−based polling

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Aseba vs Polling: Bandwidth Use w.r.t. Location

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Aseba vs Polling: Latency

150 mm/s

250 mm

initially

d

once stopped

polling 10 Hz

distance [mm]

Fre

quen

cy5 10 20 30

010

2030

polling 25 Hz

distance [mm]

Fre

quen

cy

5 10 20 30

010

2030

polling 67 Hz

distance [mm]

Fre

quen

cy

5 10 20 30

010

2030

event−based

distance [mm]

Fre

quen

cy5 10 20 30

010

2030

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Aseba vs Native

On a 40 MHz dsPIC:

I Ratio of about 70 dsPIC instructions for 1 Aseba instruction

I Rate of 600’000 instructions per second

I Event round trip lasts 25µs on idle VM

I Native functions in DSP assembly

I Native functions use dsPIC’s DSP, event round trip for meanof 100 values is 60µs, faster than bare C code

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Lessons Learnt on Performance

I Events save bandwidth compared to polling.

I Events allow for lower latencies than polling.

I Virtual machines are suitable for embedded, provided thecritical path is optimised.

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Outline

Motivation

Current Use


Performances

Wrap-up

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Future Directions

Improve IDE

I store program as abstractsyntax tree, textual surfaceform for editor

I contextualised help/errors

I intelligent completion

I statistics and machinelearning for commonmistakes, automatic tutoring

Lower entry curve

I improve tutorial

I robotics course

I more translations

More platform support

I new firmware for Thymio II

I affordable service robotbased on Smartrob

I add your favourite platform!

On the long run

I no more arithmetic/logicoperation in the VM, useonly native functions

I complete type system

I more proving in the compiler

I JIT on some platforms

I use standard language?40 / 46

Take-Home Message

The combination of VM and custom-tailored IDE enables efficientembedded development, in particular for robotic applications.

Aseba is a mature and robust implementation of this idea. Yetthere is much room for improvement and innovative ideas.

You are welcome to join us in this endeavour!

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Thank you

Thank you for your attention, your questions are welcome.

The Aseba community awaits you: http://aseba.wikidot.com

Thanks to: Michael Bonani, Florian Vaussard, Fanny Riedo, ValentinLongchamp, Basilio Noris, Sandra Moser and Francesco Mondada

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http://aseba.wikidot.com

Program Memory Layout

addresses (in 16-bit words) content

bytecodeSize −1unused bytecode

. . .

. . .bytecode for last managed event

evLastAddr

. . .. . .

bytecode for first managed eventev0Addr

evVectSize −1 evLastAddr

evVectSize −2 evLastId

. . . . . .0x0002 ev0Addr

0x0001 ev0Id

0x0000 evVectSize

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Data Memory Layout

addresses (in 16-bit words) content

variablesSize −1 temporary variables to pass. . . constants to native calls

. . . unused variables

. . .user-defined variables

exportedVarsLength

. . .exported variables

0x0000

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Types of Bytecodes - 1/2

name w.c. function

stop 1 stop executionsmall immediate 1 push a constant onto the stacklarge immediate 2 push a constant onto the stackload 1 push data from memory onto the stackstore 1 pop data from the stack into the mem-

oryload indirect 2 push data from memory onto the stack

using an offset from the stackstore indirect 2 pop data from the stack into the mem-

ory using an offset from the stackunary arithmetic 1 unary arithmetic operation on the stackbinary arithmetic 1 binary arithmetic operation on the

stack

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Types of Bytecodes - 2/2

name w.c. function

jump 1 jump to another execution addressconditional branch 2 check a condition on the stack and

jump depending on the resultemit 3 send an eventnative call 1 call a native functionsub call 1 jump into a subroutine, store return

address on the stacksub ret 1 return from a subroutine, using return

address from the stack

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aseba - open-source low-level robot programming open-source low-level robot programming st ephane...

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