Version vom 11. Januar 2017, 15:48 Uhr

Abstract

Robot Mower Communications Standard (RMCS) - *** DRAFT ***

Describes message format used to externally control a robot mower (e.g. Ardumower-based) using a serial line (PC/Raspberry/Android etc.)

TODO:

• add sensor trigger events
• add robot setup commands

Requirements

• Serial interface (or serial USB)
• ...

Message format

NMEA 0183 compatible format (ASCII encoded)

message structure: $IDMSG,data,*XX<cr><lf>

message components:

• $: start of message symbol
• ID: device ID (the destination of a command message or source of an event message) - examples: RM (robot mower), DW (ranging beacons), ...
• MSG: message type (see below)
• data: comma separated message data (see below) - if a value is not existing it should be empty
• XX: checksum: representation of two hexadecimal characters of an XOR of all characters in the sentence between – but not including – the $ and the * character.
• <cr><lf>: end of message symbol

example: $RMSTA,145984,1,,,179.8,,,0,0*3F<cr><lf>

Messages

There are command and event messages. Command messages are received by the robot, event messages are sent by the robot.

commands:

• $RMREQ: Request an event or configure message event command (frequency, one-time events etc.)
• $RMTRG: Configure a sensor trigger
• $RMMOW: Set mowing state command (start mowing, stop mowing, go to docking station)
• $RMMOV: Move robot until sensor trigger command
• $RMKOA: Keep ongoing action command (mower communications saftety)

events:

• $RMSTA: Robot state event (robot state, errors, battery, charger)
• $RMCFG: Robot mower configuration event (protocol version, available sensors)
• $RMMOT: motor current sensor event
• $RMSON: ultrasonic sensor event
• $RMBUM: bumper sensor event
• $RMODO: odometry event
• $RMGPS: GPS event
• $RMPER: perimeter sensor event
• $RMDRO: drop sensor event
• $RMIMU: IMU event
• $RMBEA: beacons ranging data event (e.g. DW1000)

Command: Request or onfigure a message event (frequency, one-time events)

This command is used to configure the frequency for an event message or to request a certain message once.

$RMREQ,MSG,f,t<cr><lf>

• MSG: the message type (CFG, STA, TRG, MOT, SON, BUM etc.)
• f: frequency (0 - 10.0 Hz), 0 means turn off periodic events for this message, -1 means fire message once
• t: enable trigger for this message (0/1)

Command: Set mowing state (start,stop,dock)

This command is used to for remote controlling the mower actions.

$RMMOW,s<cr><lf>

• s: stop mowing (0), start mowing (1), go to docking station (2)

Command: Move robot until sensor trigger

This command is used to control the robot movements directly. Once a sensor triggers (bumper, perimeter, etc.), the robot should stop.

$RMMOV,m,l,r,p,i,d<cr><lf>

• m: mowing motor on (1) or off (0)
• l: left motor target rpm
• r: right motor target rpm
• p: PID_Kp
• i: PID_Ki
• d: PID_Kd

Keep ongoing action command (mower communications saftety)

This command is used to control the robot movements directly. The mower will stop motors if not receiving another message within 2 seconds.

$RMKOA<cr><lf>

Robot state event (robot state, errors, battery, charger)

Robot will send current state via this message.

$RMSTA,ts,s,e,b,bl,c,h,d<cr><lf>

• ts: timestamp ms
• s: robot state: stopped (0), mowing (1), busy (2), error (3), going to dock (4)
• o: docking state: not docked (0), docked (1)
• e: error code
• b: battery percent
• bl: battery low (0/1)
• c: charging percent
• h: absolute compass heading in degree
• d: moved distance in meter since last message

Robot mower configuration event (protocol version, type of sensors)

Robot will send a summary of the robot's configuration via this message.

$RMCFG,p,m,d,pfl,pfr,pfc,prl,prr,prc,ih,ip,o,g,ul,ur,uc,dl,dr<cr><lf>

• p: robot is using protocol version (currently 1)
• m: robot requires minimum protocol version (currently 1)
• d: Docking station available (1/0)
• pfl: perimeterFrontLeft available (1/0)
• pfr: perimeterFrontRight available (1/0)
• pfc: perimeterFrontCenter available (1/0)
• prl: perimeterRearLeft available (1/0)
• prr: perimeterRearRight available (1/0)
• prc: perimeterRearCenter available (1/0)
• ih: IMU compass available (1/0)
• ip: IMU pitch/roll available (1/0)
• o: Odometry available (1/0)
• g: GPS available (1/0)
• ul: ultrasonicLeft available (1/0)
• ur: ultrasonicRight available (1/0)
• uc: ultrasonicCenter available (1/0)
• dl: dropSensorLeft available (1/0)
• dr: dropSensorRight available (1/0)

motor current sensor data event

$RMMOT,ts, ml, mr, mm, mlt, mrt, mmt

• ts: timestamp ms
• ml: left motor current (Ampere)
• mr: right motor current (Ampere)
• mm: mower motor current (Ampere)
• mlt: left motor stall triggered (0/1)
• mrt: left motor stall triggered (0/1)
• mmt: mower motor stall triggered (0/1)

ultrasonic sensor data event

$RMSON,ts,ul,ur,uc,ult,urt,uct

• ts: timestamp ms
• ul: ultrasonicLeft meter
• ur: ultrasonicRight meter
• uc: ultrasonicCenter meter
• ult: ultrasonicLeft triggered (0/1)
• urt: ultrasonicRight triggered (0/1)
• uct: ultrasonicCenter triggered (0/1)

bumper sensor data event

$RMBUM,ts,bl,br,bc,blt,brt,bct

• ts: timestamp ms
• bl: bumperLeft value
• br: bumperRight value
• bc: bumperCenter value
• blt: bumperLeft triggered (0/1)
• brt: bumperRight triggered (0/1)
• bct: bumperCenter triggered (0/1)

odometry data event

$RMODO,ts, ol, or

• ts: timestamp ms
• ol: left odometry
• or: right odometry

GPS data event

$RMGPS,ts, ga, go

• ts: timestamp ms
• ga: GPSlatitude
• go: GPSlongitude

perimeter sensor data event

$RMPER,ts,pfl,pfr,pfc,prl,prr,prc,pflr,pfrt,pfct,prlt,prrt,prct

• ts: timestamp ms
• pfl: perimeterFrontLeft value
• pfr: perimeterFrontRight value
• pfc: perimeterFrontCenter value
• prl: perimeterRearLeft value
• prr: perimeterRearRight value
• prc: perimeterRearCenter value
• pflt: perimeterFrontLeft triggered (0/1)
• pfrt: perimeterFrontRight triggered (0/1)
• pfct: perimeterFrontCenter triggered (0/1)
• prlt: perimeterRearLeft triggered (0/1)
• prrt: perimeterRearRight triggered (0/1)
• prct: perimeterRearCenter triggered (0/1)

drop sensor data event

$RMDRO,ts,dl,dr,dlt,drt

• ts: timestamp ms
• dl: left drop sensor value (0/1)
• dr: right drop sensor value (0/1)
• dlt: left drop sensor triggered (0/1)
• drt: right drop sensor triggered (0/1)

IMU data event

$RMIMU,ts,ih,ip,ir,tr

• ts: timestamp ms
• ih: IMUcompassHeading degree
• ip: IMUpitch degree
• ir: IMUroll degree
• tr: tilt triggered (0/1)

beacon ranging data event (e.g. DW1000)

$RMBEA,t,b1,b2,b3,b4,...<cr><lf>

• t: timestamp ms
• b1,b2,b3,b4,...: beacons ranging in meter

Proprietary

• Any proprietary message types not defined by this protocol