# All Questions

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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 ...
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 ...
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 ...
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 ...
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....
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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:...
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 ...
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?
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
29 views

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 ...
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 ...
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 ...
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 ...
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 ...
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 ...