SimPause() not pausing physics

[sguttikon]

Bug report

• AirSim Version/#commit: Master Branch
• UE/Unity version: UnrealEngine_4.25
• autopilot version:
• OS Version: Ubuntu 18.04.6 LTS

What's the issue you encountered?

As you can see from the output, when simulation is paused - the offset between car and camera position increased after sleep.
Expected: the relative position should almost remain constant since vehicle moving in straight path and simulation is paused.
May be this is an old/known issue, simPause() seems to no pausing physics engine or these is some other issue.

Settings

{
  "SeeDocsAt": "https://github.com/Microsoft/AirSim/blob/master/docs/settings.md",
  "SettingsVersion": 1.2,
  "SimMode": "Car"
}

How can the issue be reproduced?

Code Snippet:

#--- hello_car.py ---

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import airsim
import time
import numpy as np

# connect to the AirSim simulator
client = airsim.CarClient()
client.confirmConnection()
client.enableApiControl(True)
car_controls = airsim.CarControls()

for _ in range(10):
    # set the controls for car
    car_controls.throttle = -0.5
    car_controls.is_manual_gear = True;
    car_controls.manual_gear = -1
    client.setCarControls(car_controls)

    # let car drive a bit
    time.sleep(1)

client.simPause(True)
car_position1 = client.getCarState().kinematics_estimated.position
img_position1 = client.simGetImages([airsim.ImageRequest(0, airsim.ImageType.Scene)])[0].camera_position
print(f"Before pause: {car_position1.x_val - img_position1.x_val}, {car_position1.y_val - img_position1.y_val}, {car_position1.z_val - img_position1.z_val}")

time.sleep(10)

car_position2 = client.getCarState().kinematics_estimated.position
img_position2 = client.simGetImages([airsim.ImageRequest(0, airsim.ImageType.Scene)])[0].camera_position
print(f"After pause: {car_position2.x_val - img_position2.x_val}, {car_position2.y_val - img_position2.y_val}, {car_position2.z_val - img_position2.z_val}")
client.simPause(False)

Include full error message in text form

$ python3 hello_car.py 
Connected!
Client Ver:1 (Min Req: 1), Server Ver:1 (Min Req: 1)

Before pause: -1.8311004638671875, -0.010279476642608643, 0.9998747706413269
After pause: -2.0000457763671875, -0.011233329772949219, 0.9998047351837158

What's better than filing an issue? Filing a pull request :).

[rajat2004]

Thanks a lot for the reproducible example! Could you try out #4175 and see if it fixes the problem for you?

[sguttikon]

Thank you @rajat2004, it seems your changes fixed this issue. :)

[jonyMarino]

@suresh-guttikonda This somehow solves the issue you had in driving the car with the keyboard after calling simPause() as you described in #4171?

[sguttikon]

@jonyMarino Unfortunately it didn't fix the #4171, i tried the code snippet as mentioned in that issue. But still I can see x-position difference between left, center, right cameras even though i am using stereo camera setup

code snippet

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

import airsim
import time

# connect to the AirSim simulator
client = airsim.CarClient()
client.confirmConnection()
client.enableApiControl(True)
car_controls = airsim.CarControls()

while True:
    # get state of the car
    car_state = client.getCarState()
    print("Speed %d, Gear %d" % (car_state.speed, car_state.gear))

    # set the controls for car
    car_controls.throttle = -0.5
    car_controls.is_manual_gear = True;
    car_controls.manual_gear = -1
    client.setCarControls(car_controls)

    # let car drive a bit
    time.sleep(1)

    client.simPause(True)
    # get camera images from the car
    responses = client.simGetImages([
        airsim.ImageRequest("front_left_custom", airsim.ImageType.Scene),
        airsim.ImageRequest("front_center_custom", airsim.ImageType.Scene),
        airsim.ImageRequest("front_right_custom", airsim.ImageType.Scene)
    ])

    # do something with images
    print(f"Left Image   : {responses[0].time_stamp} {responses[0].camera_position}")
    print(f"Center Image : {responses[1].time_stamp} {responses[1].camera_position}")
    print(f"Right Image  : {responses[2].time_stamp} {responses[2].camera_position}")
    print("-----------------------")
    client.simPause(False)

output:

Speed 0, Gear 0
Left Image   : 1637680881635593000 <Vector3r> {   'x_val': 1.276526689529419,
    'y_val': -0.500444233417511,
    'z_val': -1.0125737190246582}
Center Image : 1637680881639327000 <Vector3r> {   'x_val': 1.2766900062561035,
    'y_val': -0.00044429057743400335,
    'z_val': -1.0125446319580078}
Right Image  : 1637680881642682000 <Vector3r> {   'x_val': 1.2768532037734985,
    'y_val': 0.49955567717552185,
    'z_val': -1.0125157833099365}
.....
Speed -5, Gear -1
Left Image   : 1637680508018565000 <Vector3r> {   'x_val': -50.67403793334961,
    'y_val': -0.5161873698234558,
    'z_val': -1.0174293518066406}
Center Image : 1637680508020641000 <Vector3r> {   'x_val': -50.67300033569336,
    'y_val': -0.016188468784093857,
    'z_val': -1.0174232721328735}
Right Image  : 1637680508023466000 <Vector3r> {   'x_val': -50.671966552734375,
    'y_val': 0.4838104546070099,
    'z_val': -1.017417311668396}

....
Speed -4, Gear -1
Left Image   : 1637680514926896000 <Vector3r> {   'x_val': -74.15702819824219,
    'y_val': -0.31434252858161926,
    'z_val': -1.0183379650115967}
Center Image : 1637680514932230000 <Vector3r> {   'x_val': -74.15306091308594,
    'y_val': 0.18564172089099884,
    'z_val': -1.0182714462280273}
Right Image  : 1637680514936044000 <Vector3r> {   'x_val': -74.14909362792969,
    'y_val': 0.6856259703636169,
    'z_val': -1.018204927444458}