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671 questions with no upvoted or accepted answers
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7
votes
2answers
392 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 ...
6
votes
0answers
184 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 ...
6
votes
1answer
4k 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 ...
4
votes
1answer
106 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 ...
4
votes
1answer
149 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....
4
votes
1answer
196 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 ...
4
votes
2answers
384 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 ...
4
votes
0answers
391 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 ...
3
votes
3answers
95 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 ...
3
votes
2answers
132 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 ...
3
votes
1answer
542 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 ...
3
votes
1answer
335 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 ...
3
votes
1answer
323 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 ...
3
votes
0answers
140 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 ...
3
votes
1answer
419 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:...
3
votes
0answers
105 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 ...
3
votes
0answers
131 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?
3
votes
0answers
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 ...
2
votes
0answers
13 views

VFH/VFH+ Axis Orientation & Sensor Angles

I have been struggling with trying to get the VFH+ implementation working correctly using Orca-Robotics implementation which seems to be the same implementation used in the ROS package and MATLAB and ...
2
votes
0answers
28 views

value of $\gamma$ in the H-infinity norm

Suppose I have the system: $\dot{x} = Ax+Bu$ $y=Cx+Du$ and the following Hamiltonian matrix: $H=\begin{pmatrix} A & \frac{1}{2}B^TB\\ -CC^T&-A \end{pmatrix}$ I want to find the value ...
2
votes
0answers
10 views

Can't set ID to Dynamixel MX-64

I have 2 WidowX robots which I already successfully address ID's for all the MX-28 and AX-12A servos using ROS code in the Arbotix controller with the Dynamanager 1.3 on a Mac but I can't detect any ...
2
votes
0answers
24 views

In SLAM loop closure, What does a sim3 matrix do?

I am confused between 3D rigid affine(with scale, without shear) transformation and Lie group's sim(3) matrix. 3D affine would be [sR|t; 0 1]. we rotate, scale and then translate a 3D point using ...
2
votes
1answer
34 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 ...
2
votes
0answers
29 views

Robot Hand to Eye calibration without joint encoder

I have two degrees of freedom robot with a camera mounted on the tool center point where the system is modeled as $^wT_c = {^wT_z}(\theta_1){^zT_m}(\theta_2) {^mT_c}(\textbf{r})$, $\textbf{r} \in ...
2
votes
0answers
45 views

Particle filter with error states

I am new to particle filters and I have a particle filter based on this: $$x_{k+1} = f_{k}(x_{k},\omega_{k})$$ $$y_{k+1} = h_{k}(x_{k},v_{k})$$ $$x = [\delta \phi, \delta \theta, \delta \psi, \delta ...
2
votes
0answers
18 views

Is it possible to calculate a homography matrix for any 2 views?

I've been experimenting with opencv to estimate the homography matrix between 2 images captured with my computer's webcam. I have noticed that when the 2 views are not very far apart (that's when I ...
2
votes
0answers
30 views

How to identificate uav's roll and pitch model and control to track object?

I'm building a drone distance controller for parrot mambo. I need to track a colored page with given distance and given heigth. I can get the yaw information from parrot mambo with 0.5 sec. Since I ...
2
votes
0answers
15 views

Undo pitching effect of camera when pose (y-axis) is near 90 degrees?

I am using KITTI odometry dataset whereby the camera's axis is pointing X (east), Y (down) and Z (north). It also contain the frame to frame poses of the camera (first pose is fixed as the map frame). ...
2
votes
2answers
217 views

Finding correct RPY for approaching a known point on a plane

I have a robot with 6 DOF that I want to use to grab a hanging sheet at a specific point near its edge. The grip needs to be perpendicular to the edge and co-planar with the point of course. I have ...
2
votes
3answers
98 views

How to create a stable 48V 10A power supply?

I'm shopping for batteries and it's easy to find a 48V lithium ion battery that has like 30A max continuous discharge rating. However, I know that the battery supply has a variable voltage from 54V - ...
2
votes
1answer
86 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 ...
2
votes
0answers
43 views

Overcoming or managing dead time in vehicle steering controller

I found out there is a dead time in my steering controller after several runs. The transfer function for it in the $s$-domain is: $$ H(s)=\frac{270 \cdot e^{-0.03s}}{0.015 \cdot s + 1} $$ To ...
2
votes
0answers
90 views

How to handle sensor data for a sensor-fusion algorithm

I am implementing the explicit complementary filter(see below) with a 9DOF MEMS sensors (accelerometer, magnetometer and gyroscope) for attitude estimation. Currently, the gyro and accel update rates ...
2
votes
0answers
32 views

Stereo Rectification when Extrinsics are known

Suppose I have two cameras $C_1$ and $C_2$ arranged in a stereo configuration. Let us assume that the camera is free of distortion with ideal intrinsics and that the camera extrinsics $R$ and $t$ are ...
2
votes
1answer
60 views

Doubt with linearization and discretization process - Ekf

In the paper "State Estimation for Legged Robots - Consistent Fusion of Leg Kinematics and IMU", the authors describe the application of an extended kalman filter to estimate states of a quadruped ...
2
votes
0answers
130 views

CNC stepper motors are loud and slow after decreasing the steps/mm from 250 to 5

I'm making a drawing robot and have hooked up my steppers to each axis. I'm using the grbl shield with arduino and nema 17 steppers. Initially the firmware was set at 250 steps/mm but with my setup ...
2
votes
0answers
102 views

Magnetometer Calibration

I'm looking at using a magnetometer in a project and I'm struggling to understand the proper procedure for calibration of the sensor. I understand that magnetometers need to be calibrated to ...
2
votes
0answers
18 views

Fiducials in conjuction with AMCL

I'm having some trouble getting fiducials (using aruco_detect) to work alongside amcl. The goal here is to use normal amcl localization when a fiducial is not present, and to switch to localization ...
2
votes
0answers
33 views

Create path with minimum curvature for Ackerman drive

I'm trying to create a trajectory between two given poses for an Ackerman drive. The poses are defined as follows: Current Pose position $(x_0, y_0)$ rotation on z-axis $\theta_0$ Final Pose ...
2
votes
0answers
77 views

Wheeled Mobile Robot State Estimation Model Using Odometry

I have a process model update that follows the form: $$ \mathbf{x}_{k|k-1} = \mathbf{x}_{k-1|k-1} + \delta \mathbf{x}_k, $$ where $\mathbf{x}_{k-1|k-1}$ is the posterior estimate from the last ...
2
votes
0answers
44 views

OpenRAVE “fast-forward” physics simulation?

I am working with OpenRAVE simulator and I am using ODE Physics (OpenRAVE plugin to support ODE). I have a robot in an environment and multiple other objects that are subject to the physics engine. I ...
2
votes
0answers
50 views

EIF slam algorithm implementation as per Probabilistic Robotics

I want to implement EIF slam from Probabilistic Robotics Table 11.2. This is the algorithm for EIF slam. To construct $\Omega and \xi$ matrix I write down a Java code. Here is my code ...
2
votes
2answers
86 views

Is pose estimation using images necessary in visual-inertial SLAM

In visual SLAM, pose estimation is performed between two adjacent frames or keyframes using feature detection and pose estitmation from corresponding features. However in visual-inertial SLAM, pose ...
2
votes
0answers
62 views

How rational is it to use Intel Realsense for my affordable indoor autonomous robot?

Right now, I am using ESP32 for the motors and planning to add either Raspberry Pi Zero or ARM Cortex-M4 (STM32) and use ROS with Intel RealSense RGBD camera. How sensible is it? I am not expert in ...
2
votes
1answer
86 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 ...
2
votes
1answer
79 views

How to avoid matrix singularity in GraphSLAM

I am trying to implement GraphSLAM from Sebastian Thrun's paper, The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures. When I compute the inverse of my information ...
2
votes
0answers
44 views

Strategy for 3D path planning over large distances with kinodynamic constraints

I was hoping to pick your brains about a problem that even after much reading has left me baffled. My Application: For the sake of simulating underwater scenarios in very large environments (up to ...
2
votes
1answer
138 views

IRobot 690 - raw wheel encoder counts change with no movement command issued

I am using a Raspberry Pi 3, B+ pertinent libraries are WiringPi, with WiringSerial. Code is written in c. EDIT: the Serial connection is handled through GPIO 14(Tx) & 15(Rx), 5v (Tx) is stepped ...
2
votes
0answers
71 views

Is there a Kinfu version that runs with ROS on an Odroid?

I have a ROS-based robot that runs on an Odroid with a 3d Camera (Openni-based) and would like to use Kinfu (or something similar) on it. I'm not sure if the Mali-GPU is fast enough, but so far I didn'...
2
votes
0answers
88 views

Position-Attitude Kalman filter with Quaternions

I want to design an EKF to estimate the position of a UAV. If I were doing this with Euler angles then I would have a state vector that would look like \begin{bmatrix}north&east&down&...

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