# All Questions

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315 views

### Is it possible to list all runtime dependencies for ROS

I've read this link: http://wiki.ros.org/kinetic/Installation/Source and have known that the command ...
5k views

### Angle Random Walk vs. Rate Noise Density (MPU6050)

I’ve made a datalog from a MPU6050 (IMU: gyroscope and accelerometer) at 500Hz sample rate. Now I want to calculate the characteristics from the gyro to evaluate the sensor. For the gyro I’ve found ...
436 views

### Reward Function for q learning on a robot

I have 2 wheeled differential drive robot which I use pid for low level control to follow line. I implemented q learning which uses samples for 16 iterations then uses them to decide the best position ...
314 views

### Wait simulation time in a non realtime ROS simulation in Python

I want to control a quadrotor with a Python script and run the simulation as fast as my laptop can, not only in real time. I've modified my world and now the simulation runs with 7-10 real time factor....
230 views

### Inferring joint orientation on multi-joint arm

Not a robotics question in the strictest sense, I guess, but related closely enough, I hope: I have an arm-like articulated two(-plus-one)-joint appliance that I want to use as a 3D input device. It ...
814 views

### Poor accuracy of hand eye calibration when using vanilla Tsai's method

I’m working on the hand eye calibration for the robotic arm. I attached the camera near the tip of the robot (or end effector) and took around 40 pictures of an asymmetric circles pattern. I ...
417 views

### Lego Mindstorms EV3 gyro sensor offset fix

I am currently working on a project for a Lego Mindstorms EV3 autopilot using Matlab/Simulink. Basically, I am using a closed loop control system with a PID controller for the control of the control ...
492 views

### Cannot disable sleep in passive mode for iRobot Create 2

I tried to disable sleep by pulsing the BRC pin low for one second every minute as suggested in the OI, but my Create 2 still goes to sleep after 5 minutes. My firmware is r3_robot/tags/release-3.2.6:...
249 views

### Yaw drift when implementing AHRS filter fusion

I am using the Matlab AHRS filter fusion algorithm with an InvenSense ICM-20948 to determine object orientation. I seem to be obtaining reasonable results however I am getting what appears to be ...
409 views

### DH parameters to solve forward kinematics problem

When solving the kinematics problem for a robot using DH parameters, if there are some passive joints between the actuator and the end effector, do I have to define the axis and transformations of ...
314 views

### MPU6050: Changing Gyro Output Range Throws off Positional Reading

I am using the MPU6050 in conjunction with an Arduino and Jeff Rowberg's i2cdev library, and my project requires that the gyro rate outputs be more precise than the default setting, which is 1/16.4 of ...
399 views

### What are good, low cost, actuators for a braille tablet to be controlled by arduino?

I want to basically make a pin matrix controlled either by spring, electromagnets or small motors(spring being the most viable option), something like what’s shown in the image. I'm pretty new to ...
421 views

### How does one implement a third order complementary filter for estimating altitude using data from an accelerometer and a barometer?

I am working with the CJMCU build of cleanflight on a small drone. As of now, the algorithm for altitude hold uses a first order complementary filter to combine data from the barometer and the ...
73 views

### Assistance in finding correct LIDAR for short-range object detection task

I am working on a task that involves finding a distance of a moving object going a static linear object, e.g a long pole. After trying some approaches (mostly involving stereo vision), I have come up ...
155 views

### Motion planning with Gaussian Process Regression

I was recently introduced to Gaussian Process Regression (GPR). I read multiple papers regarding use cases of GPR in robotics, however, they were more or less very limited. Use case from the ...
30 views

### What is the corrispettive motion convention for robotic systems with X,Y,Z axis?

We built several systems coupling multiple linear micrometric stages. I can't find a standard defining the axis convention of these kinds of systems, it there are any. Regarding the system on the ...
34 views

We all know that the fly time of a quadcopter is proportional to its weight (and the propellers size, etc), and a high capacity battery is heavy, but also a high capacity battery would make the fly ...
36 views

### Calculation of error, based on camera images

I am trying to measure the precision error of a gripper that is mounted to the flange of a 6 DOF industrial robot. The gripper-design is rather complex, therefore we would like to make sure it is ...
60 views

### How to get unix/posix time stamp in header of ROS msg?

I am using two sensors each connected to different machine (each machine separately runs Ubuntu 16.04 and ROS Kinetic). When I echo topic on these two machines, I ...
45 views

### building a grid map from gps trajectory poses

I am trying to create a feature grid map with Images from camera mounted to the top of the car. Novatel ProPak RTK gps poses Beforehand, I've checked to ensure that the standard deviations of the ...
141 views

### Building a stationary robot. ROS the right tool for me?

I'm wondering if ROS is the right system for me. I'm currently involved in a project which consists of building a device that has the purpose to take spectroscopic measurements using a laser and a ...
124 views

### SEIF ,online version of Graph slam create doubt in Motion Update state

I have a thesis work about Graph Slam The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures I try to implement it with the help of this paper but during the ...
182 views

### How should I understand sequential importance resampling in a particle filter?

Suppose I implement a particle filter with $n$ particles. This is a brief description of my understanding of a particle filter. For the first step, I throw out $n$ particles some distance from my ...
136 views

### How can I receive Genicam packets from a device in a docker container?

I installed a command line tool which accepts genicam packets from a device as input into a docker image. If I use the option --network host in the ...
803 views

### Correctly calculating free acceleration given NED referenced orientation quaternion and sensor referenced acceleration data

I have a sensor outputting correct, calibrated North-East-Down referenced quaternions describing the orientation of the sensor. It also outputs raw, sensor referenced acceleration data, inclusive of ...
222 views

### Examples of Zeno Behaviour in the Real World

Zeno Behaviour or Zeno Phenomenon can be informally stated as the behavior of a system making an infinite number of jumps in a finite amount of time. While this is an important Control system problem ...
280 views

### Triangulation from calibrated stereo rig

I am using a stereo rig to do SLAM, calibrated using the MATLAB Calibration Tool. I need to compute the 2D coordinates of a landmark using the observation model obtained from triangulation (the images ...
106 views

### Maximum ball screw speeds

What is the maximum rotational velocity of miniature ball-screw (diameters up to 12mm) for approximately 1000 thrust cycles, and which type/brand would that be, if the speed is limited by the ball ...
138 views

### On-board monocular odometry for quadcopter stabilization

Has anyone done this with EKF/PID on a small microcontroller? Or know of code snippets to help implementing this?
99 views

### choose ZigBee modules for full wireless mesh

What is the most common ZigBee IP Modules to create full wireless mesh mode? I know that it should be 1) coordinator and 2) router to create full-mesh But I am interesting about what kind of modules ...
134 views

### How is the GPS fused with IMU in a kalman filter?

I've been trying to understand how a Kalman filter used in navigation without much success, my questions are: The gps outputs latitude, longitude and velocity. While the IMU outputs acceleration and ...
45 views

### Kalman Filter for 2d pose

I'm really sorry if this is a dumb question, but I don't have a clue on how to do this. I'm trying to write a kalman filter with a State vector of : {x, y, ẋ, ẏ, ẍ, ÿ } To estimate the 2 dimensional ...
48 views

### 2D Visual-Inertial Extended Kalman Filter

I am trying to implement an Extended Kalman filtering for combining IMU data and visual odometry in a simple 2D case where I have a robot that that can only accelerate in its local forward direction ...
22 views

### How do you handle angle discontinuities in estimation problems?

When one is implementing a state estimator in a system that involves kinematics, will inevitably face the problem of angle discontinuities, i.e., the fact that the angles have to be wrapped between ...
23 views

### Roomba iRobot Create 2 Open Interface, is there a way to turn off vacuum motor while the robot is docking?

I am able to control every desired aspect of my robot, except for vacuum motor which seems to be turned on for some reason every time I send Seek Dock (code ...
41 views

### Applying initial guessing to LiDAR point cloud for ICP processing in Graph SLAM

I am currently in the process of implementing Graph SLAM using ICP and g2o in python 2.7 The data I have are pose data (4 x 4 transformation matrix) and lidar data ( in the format of [x y z 1] with ...
40 views

### Is it possible to track position using gyroscope and accelerometer without a magnetometer?

I'm looking for help on a project where I will be placing sensor data in 3D space using augmented reality. Most solutions I have found for finding position with an IMU involve the magnetometer, but ...
33 views

### Robot - Wall Avoiding (Plinko Robot)

I am looking to build a robot that will travel and zig-zag down the hallway.It will be headed towards a wall at roughly 45 degrees and then use a IR LED to detect when a wall is nearby. From there, ...
37 views

### Motor acceleration and position with PID control

I'm working on a robot with differential drive (2 drive wheels equipped with rotary encoders and 4 free spinning omni wheels for stability) and each wheel is controlled via a separate arduino nano. I ...
58 views

### Jacobian of a planar manipulator with 4 links

I have a mobile manipulator that moves on the plane. The base moves in SE(2) and the manipulator is also planar with 4 links. The mobile base will be a differential drive robot and its motion is ...
38 views

### How to calculate what motor I need to move weight

I'm working on a project trying to make some electric roller curtains. I can use 2 motors on this curtain, on each side to lift and pull down the curtain. Pulling down the curtain requires not as much ...
28 views

### Bevel Gear Compatibility

ServoCity sells a great little 2:1 bevel gear ratio set: https://www.servocity.com/2-1-bevel-gear-set-1-4-bore-pinion-1-4-bore-spur I have it currently set up in my project and was thinking a 1:1 ...
104 views

### Are Rospy subscriber callbacks executed sequentially for a single topic?

Suppose a ROS node receives new batch of data on a topic while the previous batch is still being processed by callback. Will ROS wait for its completion or will it spin a new thread and run both at ...
44 views

### Waking Up Roomba Over Serial

Sorry if this is a noobie question, it's my first time posting on this forum... I've been trying to mod an old Roomba 400 series (model #4220) by adding a raspberry pi to it. (I know real original ...
41 views

### Corrupted Robot Model in Gazebo

I'm trying to run multiple instances (18 instances) of gazebo in parallel processes on my system to do reinforcement learning. However i'm running into an issue where the robot model in some of the ...
48 views

### Make robot drive as far from obstacles as possible

I am trying to make robot drive around the room, avoiding obstacles with pathfinding. The problem is I get few waypoints from pathfinding algorithm for robot to drive to (green dots), but it drive a ...
32 views

### Trajectory tolerance limits

I have a trajectory planner, which calculates the trajectory assuming that the robot is following the planned trajectory. From sensors I get the position of the robot, which has an offset from the ...
50 views

### Can't run DC Motor with Arduino and Adafruit Motor Shield

I'm very new with Arduino and Adafruit and I'm trying to get a DC motor running with my Adafruit Motor Shield V2.3, but it's not running. I have connected the motor to the right terminal (M3). I'm ...
20 views

### Checking for external compass in mission planner

How can I check whether the external compass is really selected for my APM 2.8 using mission planner. The primary purpose of using the external compass is to have less electro magnetic interference ...
40 views

### Designing own robot for Gazebo simulation?

For my project I am trying to model and control a quadrotor with actuating arms. As I don't have a physical model with me, I want to simulate and control the robot using ROS and Gazebo. At the ...

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