Body sensors and units

Every value nao-rs decodes from the chest board and the head, with its index, unit and source, and the units of the robot API.

nao-rs decodes the body sensors from the chest board's answers into LoLA's arrays, order and units, so software written for LoLA reads the same numbers. In two recordings, 279,186 values in 1,767 of LoLA's messages came out bit-identical. This page lists the runtime's state; the robot API's units follow at the end.

The runtime's state

Field	Size	Unit	Source
`accelerometer`	3 (x, y, z)	m/s²	Inertial unit; ±9.81 m/s² per 16,384 counts
`gyroscope`	3 (x, y, z)	rad/s	Inertial unit; 500 °/s per 32,768 counts
`angles`	2 (x, y)	rad	Inertial unit's own orientation estimate, with the offsets from the preferences
`battery`	4	see below	Battery
`fsr`	8	kg	Foot boards; pressure sensors with the gains and offsets from the preferences
`sonar`	2 (left, right)	m	Sonar board; first echo, 0.01 m per count
`touch`	14	0 or 1	Chest board, foot boards, hand boards, head bus
`position`	25	rad (hands: 0..1)	Joint boards
`current`	25	A	Joint boards; 0.016 A per count
`temperature`	25	°C	Joint boards; steps of 2 °C
`status`	25	0..3	Temperature status per joint: 0 normal, 1 above the minimum, 2 near the maximum, 3 at the maximum
`stiffness`	25	0..1	Not measured: the stiffness that was commanded, as LoLA reports it

Joint arrays follow LoLA's joint order (see Architecture).

Joint values need accepted motor boards

Positions, currents, temperatures and the hand touch sensors come from the motor boards. Until nao-rs accepts the robot's version 11 boards (planned), they are not checked against real data.

Battery

Index	Value	Unit
0	Charge	0..1 (values outside are dropped)
1	Status	Bit field from the battery's status register
2	Current	A; negative while discharging
3	Temperature	LoLA's scale: the 0.1 factor is applied twice, so 28.5 °C reads 2.8

Foot pressure

Index	Sensor
0, 1, 2, 3	Left foot: front left, front right, rear left, rear right
4, 5, 6, 7	Right foot: front left, front right, rear left, rear right

nao-rs also computes each foot's total weight and centre of pressure the way HAL does, from the sensors' positions in the foot. LoLA never sends these.

Touch

Index	Sensor	Index	Sensor
0	Chest button	7	Left hand, left
1	Head, front	8	Left hand, right
2	Head, middle	9	Right foot bumper, left
3	Head, rear	10	Right foot bumper, right
4	Left foot bumper, left	11	Right hand, back
5	Left foot bumper, right	12	Right hand, left
6	Left hand, back	13	Right hand, right

Head readings

The head bus adds values that LoLA reads but never sends to its client. nao-rs reports them:

Value	Unit	Device
Head voltage	V	INA230 power monitor, 1.25 mV per count
Head power	W	INA230
Head current	A	INA230
Face temperature	°C	TMP100, about every 300 ms; 0 until the first reading

On the robot: 24.8 V, 10.7 W and 43 to 47 °C.

Checked live

With HAL stopped and nao-rs reading the chest board: gravity at −10.4 m/s², gyroscope at about 0, battery at 99 %, and the sonar following a person between 0.4 and 1.7 m.

Still open, checkable without motors: the physical order of the head pads (front, middle, rear), of the foot pressure sensors and of the bumpers needs one touch of each; and whether the gyroscope's zero offset is ever nonzero.

The robot API's units

The robot API sends a converted state at 20 Hz:

Field	Unit
`battery.charge`	0..1
`battery.current`	A, negative while discharging
`battery.temperature`	LoLA's scale (see above). The REST API reports whole degrees Celsius instead
`battery.charging`	`true` when the current is above 0
`imu.linear_acceleration`	m/s²
`imu.angular_velocity`	rad/s
`imu.roll_pitch`	rad
`sonar`	m, left and right
`left_foot_pressure`, `right_foot_pressure`	kg: front left, front right, rear left, rear right
`touch`	booleans; each hand and foot is one value (any of its sensors)
`joint_positions`	rad, 26 values in the API's joint order
`joint_temperatures`	°C
`joint_currents`	A