Questions tagged [real-time]

Real-time software is one with tasks that have critical timing requirements. Failure in delivering results within the timing requirement results in catastrophe at worst and uselessness of the results at best.

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How mature is real-time programming in robotics? [closed]

Edit: I don't know why, but this question seems to be confusing many people. I am aware of when/where/why/how to use real-time. I am interested in knowing whether people who have a real-time task ...
Shahbaz's user avatar
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7 votes
1 answer
4k views

Is ROS hard real time safe?

I know that is a question that has been asked too many times, but still its not clear to me. I read online that it isn't but some people say that they control their robots under ROS in applications ...
jason's user avatar
  • 79
6 votes
3 answers
8k views

Camera selection for long range stereo vision system (up to 100 meters)

I want to implement a real-time stereo vision system for long range (up to 100m) depth estimation. I know that there are some general considerations as described in this SOV post. I have seen some ...
Mr. Nobody's user avatar
6 votes
3 answers
746 views

PID Integration over not constant dt (∆time)

Is integration over not constant dt (∆time) a possible thing? Let's say you have a PID loop with differentiating frequency, can the integral part of it still work? (Assuming you know the dt from the ...
Dan Barzilay's user avatar
6 votes
1 answer
2k views

Python libraries for image processing and feedback control on raspberry pi

I'm building a motion detection and object recognition camera with feedback control for a hexy robot. Fortunately most of the servo control is handled by the analog servo controls and the high-level ...
hobs's user avatar
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3 votes
1 answer
2k views

Why does ROS2 claim to be "real time"?

ROS2 uses DDS, in the wiki it says that DDS is "The Data Distribution Service (DDS) for real-time systems is an Object Management Group (OMG) machine-to-machine (sometimes called middleware or ...
Ricardo Casimiro's user avatar
3 votes
1 answer
156 views

How can I measure latency in a CAN bus?

Given a CAN bus with one master and any number of motor drivers, is there a way to measure the time between sending a command from the master (e.g. a PC running ROS) and the execution of the said ...
mohsen's user avatar
  • 31
3 votes
3 answers
928 views

Software real-time of ROS system

As far as I know, a hardware real-time robot control system requires a specific computing unit to solve the kinematics and dynamics of a robot such as interval zero RTX, which assigns CPU cores ...
Superuser's user avatar
  • 185
3 votes
1 answer
679 views

How to eliminate motion blur with realtime performance

I have a robotic system to develop, in first phase of the project I need to track an object. So I placed a geometrical marker on the object to estimate it's pose (rotation, translation). It all works ...
Muhammad Abdullah's user avatar
3 votes
2 answers
1k views

Robot Calibration using DH parameters

I'm new in robotics. My problem is the next one: I have a 6DOF robot manipulator and because the implementation was for real-time application my calculation time had to be really fast so that I used ...
Paul Tumbaco's user avatar
3 votes
0 answers
767 views

real-time stereo vision system for long range (up to 100m) depth estimation

I want to implement a FPGA-based real-time stereo vision system for long range (up to 100m) depth estimation. Also, I want to use two ip cameras in the system. I have calculated depth error using the ...
Mr. Nobody's user avatar
2 votes
1 answer
288 views

What is the best adaptive controller for robotic arms?

I have a question that lays on practical experience. What is the best adaptive controller for a robotic arm? Self Tuning Regulator (STR) Model Reference Adaptive Controller (MARC) Adaptive Model ...
euraad's user avatar
  • 311
2 votes
2 answers
2k views

Real-time camera localisation in known environment

I am young researcher/developer coming from different (non-robotic) background and I did some research on camera localisation and I came to the point, where I can say that I am lost and I would need ...
Excalibur's user avatar
2 votes
4 answers
766 views

Path of the robot

I have built a simple robot which will move from a source to destination. I want to record a 2d path which the robot has taken in real time. Something which is similar to the image I have take.(...
Anurag A S's user avatar
2 votes
3 answers
7k views

Is it possible to use an arduino in hard real time

I am using the ros_arduino_bridge to control a robot, by connecting the Arduino to a main pc with a usb cable. I was thinking of using the Arduino with main pc with a serial cable and then doing real ...
user avatar
2 votes
2 answers
891 views

Controlling bot using video and image processing

I am going to start a project on controlling robots using hand gestures. Though I have used MATLAB for this purpose earlier, I realized it is extremely slow for any practical real-time system. I am ...
uncreative's user avatar
2 votes
1 answer
732 views

Real time implementation of EtherCAT master with ros_control

I want to control a motor using EtherCAT protocol. 1. I used IgH ethercat master to control motor in hard real time (1 kHz). 2. Later I want to integrate this in ros_control with hard real-time ...
Piyush's user avatar
  • 21
2 votes
1 answer
528 views

How does one calculate distance and angle using a target with known measurements?

The target is in the shape of a U where the horizontal segment is 20 inches, and the two vertical segments are 14 inches. We are using a camera to image the target, and then using vision processing to ...
LEGOman420's user avatar
2 votes
0 answers
21 views

Coordinating long-running actions with independent threads [closed]

Basically, some things have real-world durations that need to be accommodated. For example, moving a servo arm 180° will take a significant number of milliseconds. What is the best practice for ...
RoUS's user avatar
  • 121
2 votes
1 answer
93 views

Low latency control from a laptop

Lets say that I needed to send sensor readings in increments of 100 bytes from a micro controller to a laptop with sub 2 ms latencies in real time (the data needs to be processed and acted upon ...
David's user avatar
  • 420
1 vote
2 answers
817 views

Raspberry Pi for two wheel robot?

I want to create a two wheel remote controlled robot. I have worked out a lot of the logic with regards to balancing. I have started to read up on motor control and arduino vs beagleboard black vs ...
frodeborli's user avatar
1 vote
3 answers
129 views

When is the case to use hard real time?

If I use an industrial robot with its hardware controller, should I install linux hard real-time like xenomai to use this kind of hardware controller? If not, when is the case to use xenomai?
sam's user avatar
  • 111
1 vote
1 answer
1k views

Is it possible to use ROS2 real-time on a computer and connect to the robot actuator using a CAN bus?

I am using ROS2 real-time (still a lot to learn) to implement the various control element of my robot : SLAM, path planning, controller, etc... For the first step of prototyping we would like to build ...
Dawi's user avatar
  • 43
1 vote
1 answer
100 views

Real Time Motion Control [closed]

How is real time control normally handled? Do you run a separate motor control unit which has its own RTOS or is there some other way?
FourierFlux's user avatar
1 vote
3 answers
617 views

Real time operating system for robotics vision

I have robot vision system which consists of conveyor with encoder, two cameras (gigabit eth and usb) and simple illuminator. I need to trigger cameras and illuminator when encoder reaches position ...
krzych's user avatar
  • 11
1 vote
1 answer
187 views

controlling industrial servo with pc

these days I'm learning Orocos patched with xenomai. Although I have found the ways to create a hard real-time control software, I didn't find any information on how I should use this to control the ...
user avatar
1 vote
0 answers
111 views

Real-time python reinforcement learning library

I'm looking for a reinforcement learning library that can be used for real-time robot control. What I first had in mind was ROS to describe the robot, Mujoco to simulate physics, and OpenAI gym to ...
makons's user avatar
  • 111
1 vote
0 answers
107 views

rtt-exercise building error-orocos-toolchain

I am using ros kinetic in ubuntu 16.04. My first error is: ...
user avatar
1 vote
1 answer
939 views

Is pyserial real time

I am using arduino with FreeRTOS and a computer with patched xenomai linux. I am using python library called pyserial to communicate with arduino. Right now I am using simple servo motors. I want to ...
user avatar
1 vote
1 answer
180 views

Ultrasonic Sensor's Lag (20Hz) effect on PID contol loop rate (150Hz)

Good day, I would like to ask how is it possible to use an ultrasonic sensor for altitude hold in a quadcopter if the sampling rate of the Ultrasonic sensor (HC-SR04) is only 20Hz before incurring any ...
user123456098's user avatar
1 vote
2 answers
265 views

Interfacing GPU image processing with motor control at 30+Hz

I would like to make a robotic system which takes as input a video feed, runs some GPU-based image recognition on the video, and outputs commands to a set of motors. The goal is to have the motors ...
user avatar
1 vote
0 answers
103 views

Microcontroller for running Linux RTAI

I'm a beginner in Robotics. I'd like to ask what are the minimum/recommended specs for a microcontroller to run a real-time system such as Linux RTAI? What is the popular microcontroller for ...
Vinko's user avatar
  • 111
0 votes
1 answer
128 views

hard realtime signal processing

I am going to realize a real time monitoring system for medical care and finally the system should make phone calls according to the severity of the result , I would like to know is it best to perform ...
Abyr's user avatar
  • 5
0 votes
1 answer
1k views

Quadcopter PID Tuning for Altitude Hold/Position Hold along Z axis

Good day, I have just finished tuning the Pitch and Roll PID's. I did this by setting the throttle such that the quad is weightless. I did the tuning of each axes separately. I would just like to ask ...
user123456098's user avatar
0 votes
1 answer
36 views

Time synchronization

I have a robot receiving images from a camera. Now, there is a denso device for time synchronization so that we get correct time stamping between of the camera frames. I am not sure what does that ...
Avv's user avatar
  • 105
0 votes
2 answers
106 views

How to keep a sensor pointed downward

I am using LIDAR to measure a robot's altitude. The robot's orientation relative to the ground is dynamic; i.e. the XY plane tilts relative to the Z axis. I would like the LIDAR to remain pointed ...
grahmW's user avatar
  • 1
0 votes
1 answer
189 views

Robots and RTOS

Many computing platforms used by robots are not real time(ex Jetson). How are real time constraints handled in real robots? Are all software transfered into a hardware solution with real time ...
FourierFlux's user avatar
0 votes
2 answers
123 views

PID control loop and feedback acquisition synchronization

In many real-time PID control loop application I have seen that the control loop is triggered exactly as the ADC interrupts arrives in order to achieve maximum synchronization between feedback ...
Roberto Maisto's user avatar
0 votes
1 answer
115 views

Head movement using gyroscope

I have a headset that provides 3 axis gyroscope readings. I wish to find out movement of head for e.g. if a person is nodding left to right etc. But the headset give me values in angular velocity for ...
Nihal Karne's user avatar
0 votes
3 answers
169 views

The reason(s)/benefit(s) to use realtime operating system instead of while-loop on MCU

I'm working on a wheeled-robot platform. My team is implementing some algorithms on MCU to keep getting sensors reading (sonar array, IR array, motor encoders, IMU) receive user command (via a ...
Qiao's user avatar
  • 121
0 votes
2 answers
222 views

How to get live audio from robot?

I am building a robot and I want to be able to hear sounds from it's environment (ideally from my laptop). What is the best way to get live audio from my robot's microphone to my computer? I have ...
Gunther's user avatar
  • 123
0 votes
0 answers
24 views

How to modify the parameters of ROS 2 in real-time?

We know that parameters can be adjusted dynamically in ROS, for example, when using the TEB local planner, the parameters can be dynamically adjusted. In ROS 1, I did this: ...
user38253's user avatar
0 votes
2 answers
79 views

Best practices for real-time capabilites in ROS2

We are designing the software stack for an autonomous racing vehicle. The high speeds require good real-time capabilities of the software stack. Are there some resources on best practices or tutorials ...
user avatar
0 votes
1 answer
36 views

control real-time processes with ROS/ROS2 on multicore system

I was wondering if it would be possible to replace a PLC running real-time processes completely by an IPC running Linux and ROS or ROS2. We have already experience in running an ethercat master at 1ms ...
user avatar
0 votes
1 answer
1 view

Why rttest allocates 8GB of memory?

Hello, i'm going thru rttest ulitity and was wondering why "lock_and_prefault_dynamic()" always locks 8GB of heap memory? Steps to reproduce: Build as described in README.md Set unlimited ...
user avatar
0 votes
1 answer
4 views

What does real-time safe means?

Hi, I have read some ROS tutorials and articles on the web referring to "real-time safe". I do know what "real-time" means but I don't know what "real-time safe" means. ...
user avatar
0 votes
1 answer
8 views

ROS2/pendulum demo (and rttest/example_loop) get killed if 8GB free RAM is not satisfied

Hi ! I am using Ubuntu 16.04 with a real-time patched kernel (4.14.93-rt53). I have tested my system with cyclic tests and am happy about the realtime performance. I have built and installed Ros2 (...
user avatar
0 votes
1 answer
2 views

The question about ros::publisher and ros::subscriber

I want to achieve receiving and transform data using rostopic at the same time or in a low time. I know that ros::subscriber can subscribe rostopic and receive the data included in topic. So I hope ...
user avatar
0 votes
1 answer
4 views

Making ROS real-time : is it magic?

Greetings, I was wondering about real-time patches for ROS, such as Orocos, and their actual efficiency. I am quite new in the field of RT stuff, but as I read that ROS wasn't an real-time software, I ...
user avatar
0 votes
1 answer
5 views

ros_control and RT

Dear all, The doc for ros_control says controller_manager provides a hard RT loop. knowing that ROS is designed for non-RT OS (plain linux), how is that possible on a non-RT OS? how does that relate ...
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