Lesson 3 · 15 min
Before you send any command, you need to know whether the robot is alive, upright, and cool. In this lesson you listen to the G1's state for a few seconds, measure the rate instead of memorizing it, and summarize tilt, torque, and temperature, saying "sem dado" when the simulator doesn't send a field.
Start the lesson
Goal: measure the G1's state rate and summarize tilt, torque, and temperature, without making up what the simulator doesn't send.
Click each block. Exact names from the unitree_hg IDL (SDK 814556d).
Topic: rt/lowstate. In ROS 2 (lesson 6) the same topic shows up as /lowstate.
Click each one.
In the simulator, the state goes out every 5 ms step (SIMULATE_DT in config.py): 200 Hz, and the monitor measures that.
The real robot's rate is not in the SDK code. Measure it with the monitor or with ros2 topic hz (lesson 6) instead of copying a number from a table.
With the quaternion (w, x, y, z), the cosine of the angle between the torso's vertical axis and the vertical is 1 − 2(x² + y²).
Standing, close to 0°; lying down, close to 90°. It is a single number, easy to put in a threshold.
op.inclinacao(q) returns the angle in degrees; the monitor keeps the largest value in the window.
The simulator sends temperature = 0 on every motor. Reading that as "0 °C" is making it up.
The monitor says "sem dado". On the real robot, the temperature threshold comes from the manufacturer's manual, not from a number you memorized.
The simulator runs for 10 s with the G1 suspended; the monitor listens for 5 s and exits with code 0 if the rate is in range.
F=${FTH:-$HOME/fth}; cd $F/operar && . $F/.venv/bin/activate
python3 kit/sim.py --s 10 --suspenso &
python3 kit/monitor.py --s 5; echo "saída: $?"
wait for i in range(op.N):
tau[i] = max(tau[i], abs(s.motor_state[i].tau_est))
temp = max(temp, max(s.motor_state[i].temperature))simulador: G1 29 motores · DDS domínio 1 em lo · 10 s · suspenso: sim amostras em 5 s: ≈ 1000 · taxa ≈ 200 Hz taxa dentro de 150–250 Hz: sim inclinação máx. do tronco: 6° maior torque estimado: 0 N·m (sem comando: motores soltos) temperatura máx. dos motores: sem dado (o simulador manda 0) saída: 0 simulador: fim em t = 10.0 s · robô suspenso (pés fora do chão)
Robot suspended and with no command: torso almost upright, zero torque (motors loose) and temperature with no data.
If you print max(temperature) without thinking, you see "0" and conclude the motor is cold. In the simulator the field is not filled in. Kit rule: a missing value is "no data", never a number.
Measure, don't memorize.
Run the block and write down the rate and the maximum tilt.
Done when: python3 kit/monitor.py --s 5; echo "saída: $?" → taxa dentro de 150–250 Hz: sim, temperatura máx. dos motores: sem dado (o simulador manda 0) and saída: 0.
Open kit/monitor.py and find the line that swaps the zero for "sem dado". In one line, write what you would do on the real robot to get the number.
Done when: grep -c "sem dado (o simulador manda 0)" kit/monitor.py → 1, and your line cites the manufacturer's manual as the source of the threshold.
The explanation appears after your answer.
Question 1 of 4
Where is the G1's battery in the SDK messages?skill
Question 2 of 4
The monitor measured about 200 Hz in the simulator. What does that say about the real robot?
Question 3 of 4
All motors show temperature = 0 in the simulator. What is the right reading?
Question 4 of 4
With the IMU quaternion, how do you get the torso tilt?
Choose an option. The explanation appears after your attempt.