Version vom 8. Januar 2017, 18:12 Uhr

Robot Mower Communications Standard (RMCS)

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

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: $RMSEN,1,1,,,,0,1,,0,179.8,,,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:

• $RMMOW: Set mowing state command (start mowing, stop mowing, go to docking station)
• $RMFRQ: Set message event frequency command
• $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)
• $RMTRG: Robot sensor trigger event (sensor trigger counters)
• $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
• $RMIMU: IMU event
• $RMBEA: beacons ranging data event (e.g. DW1000)

Set mowing state command (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)

Set message event frequency command

This command is used to set the frequency for an event message.

$RMFRQ,MSG,f<cr><lf>

• MSG: the message type (RMMOT, RMSON, RMBUM etc.)
• f: frequency (Hz) - 0 means turn off mesage

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

Robot will send current state via this message.

$RMSTA,ts,s,e,b,bl,c,h,l,r<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
• l: left odometry counter
• r: right odometry counter

Robot sensor trigger event (sensor trigger counters)

Robot will send a summary of triggered sensors via this message.

$RMTRG,ts,ml,mr,bl,br,bc,pfl,pfr,pfc,prl,prr,prc,t,ul,ur,uc<cr><lf>

• ts: timestamp ms
• ml: motorLeftStall
• mr: motorRightStall
• bl: bumperLeft
• br: bumperRight
• bc: bumperCenter
• pfl: perimeterFrontLeft
• pfr: perimeterFrontRight
• pfc: perimeterFrontCenter
• prl: perimeterRearLeft
• prr: perimeterRearRight
• prc: perimeterRearCenter
• t: robot orientation tilt
• ul: ultrasonicLeft
• ur: ultrasonicRight
• uc: ultrasonicCenter

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,i,d,pfl,pfr,pfc,prl,prr,prc,ih,ip,o,g,ul,ur,uc<cr><lf>

• p: robot is using protocol version (currently 1)
• m: robot requires minimum protocol version (currently 1)
• i: messages implemented bitmask ($RMMOW, $RMSTA, $RMSEN, $RMTRG, $RMCFG, $RMMOV, $RMKOA, $RMBEA) - example: 10001000
• 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)

Move robot until sensor trigger command

This command is used to control the robot movements directly.

$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>

motor current sensor event

$RMMOT,ts, ml, mr, mm

• ts: timestamp ms
• ml: left motor current
• mr: right motor current
• mm: mower motor current

ultrasonic sensor event

$RMSON,ts, ul, ur, uc

• ts: timestamp ms
• ul: ultrasonicLeft
• ur: ultrasonicRight
• uc: ultrasonicCenter

bumper sensor event

$RMBUM,ts, bl, br, bc

• ts: timestamp ms
• bl: bumperLeft
• br: bumperRight
• bc: bumperCenter

odometry event

$RMODO,ts, ol, or

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

GPS event

$RMGPS,ts, ga, go

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

perimeter sensor event

$RMPER,ts, pfl, pfr, pfc, prl, prr, prc

• ts: timestamp ms
• pfl: perimeterFrontLeft
• pfr: perimeterFrontRight
• pfc: perimeterFrontCenter
• prl: perimeterRearLeft
• prr: perimeterRearRight
• prc: perimeterRearCenter

IMU event

$RMIMU,ts, ih, ip, ir

• ih: IMUcompassHeading degree
• ip: IMUpitch degree
• ir: IMUroll degree

beacon ranging data event (e.g. DW1000)

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

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

Proprietary

• Any proprietary message types not defined by this protocol