# All Questions

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### Sensor options for localization on linear rail

For a thesis project for ways to localize a slide on a linear rail with a length of ~1m. The slide in question is the seat of an indoor rowing machine: Concept2 Ergometer Price is definitely an issue ...
6 views

### A* alogorithm Path Planning in ROS

Can anyone help me out on how to do A* path planning in ROS. I went through a lot of resources, but most of them are using a 2d graph? I just want to know the process or workflow.
18 views

### What is the degree of freedom of the following drone?

This might be a stupid question to ask here .i am confused whether the dof of this drone is 3 or 4?
17 views

### Looking for a way to run a linear servo with one stop. (Non-Arduino)

Is it possible to wire a linear servo on a 3 position switch to run in and out with one stop in the middle without using an arduino?
25 views

### Block algebra and normal algebra inconsistent

I've been playing around with some block maths, mostly trying to remember how it actually works, and I've come to a simple example that should be reduced, however when doing the normal maths, compared ...
18 views

### How to get transformation between a camera and a CNC plotter?

I have a question about robot and camera calibration. I have experience to calibrate btw 6DOF robot arm and hand-eye camera. But this time I should use a machine like CNC plotter. This machine can ...
42 views

### Should robots have rights? [on hold]

I have a question. If we are able to make robots be as human-like as possible, then should they have rights? If so, would they be human rights or specific robotic rights, sort of like how there's a ...
14 views

I have a question about SLAM. Is it common for SLAM to be used for mere map generation? For instance, have a map generated using ORB-SLAM and then freeze the map for future path planning where future ...
55 views

### What are wheel ticks and wheel impulses?

I'm tracking the position of a vehicle along a certain trajectory using the Kalman filter and we have odometry data provided to us which gives the x-position of the vehicle, y-position of the vehicle ...
25 views

### Convert Vehicle coordinates to World coordinates for positioning

I'm tracking the position of a vehicle along a certain trajectory using the Kalman filter and the idea is to check for improvements in position estimation through fusion of data from multiple sensors (...
35 views

### How timer interrupt is handled in the presence of other interrupt services?

When timer interrupt is received, if there is already some ISR being executed, doesn't it delay (elongate) the time interval measured? If yes, how is it handled? For the sake of precise time ...
37 views

### Why would I use three state variables for a second order system? [state space modeling]

I'm currently being asked to write a state space model of a falling object (equation attached). I had taken a linear systems course five years ago in which I did a lot of conversion between high ...
24 views

### Constant Offset matrix

I've been reading about controlling systems via momentum wheels. Such as in Satellites, or fancy inverse pendulums. In a particular paper, the writer tries to explain away an offset and settling of ...
41 views

### Calculating Error of Arm Manipulator

How can we calculate the error position of arm manipulator? Let's say we have a Transformation Matrix: \begin{bmatrix} R_{00} & R_{01} & R_{02} & x\\ R_{10} & R_{11} & R_{12} &...
86 views

### question about spatial velocity in the book <modern robotics>

I think the equation(3.73) should be: $\dot p-w_s$x$p=\dot p-\dot p=0$ have no idea how it can be wrong and don't know the difference between infinitely large body and a body just include the fix-...
9 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 ...
25 views

### How does sensor fusion help in robot localization

Good day... Sorry for bigner quesion, but really I need some friendly explanation rather than long reference I have 9 dof mpu9250 imu and gps. I found some source that calculate euler angle in ardunio ...
19 views

### Line Following Acute and Right angles and Proportional steering help

I am trying to figure out the logic for a line follower with the path shown in the attached image. I am having trouble with <= 90 degree angle turns. So far, I have been using the logic where if ...
22 views

### Is there a specific way or module I can use to stream video data from a camera hooked to an Arduino Uno board?

I'm currently thinking about the feasibility of creating a robot which streams live video footage and other data such as temperature, humidity, etc. to a smartphone. Is it possible to do this on an ...
26 views

### IR sensor spacing in sensor array relative to line width

I'm trying to build a line follower bot that follows a 3cm wide black line. I have a line sensor array with 6 analog sensors spaced 1cm apart. This means that in an ideal situation, i.e bot going ...
27 views

### Robot moves sideways in RVIZ ROS

I'm using robot_localization to fuse odom, imu and gps data on a husky robot. After fusion, the robot now moves forward in gazebo but sideways in rviz. I found this question. But the suggested ...
15 views

### What is the baseline of a RGBD camera?

I'm looking at some ORB SLAM2 settings where there's a parameter for "IR projector baseline times fx". Could someone here explain what exactly is the baseline of an IR projector? Is it the distance ...
26 views

### Unlabelled pins on this L293D dual DC motor driver

I've got this board from a local store. It's an L293D based dual DC motor driver. All the pins are labelled except the 5 on the bottom as shown in the picture below. Couldn't find any datasheet or ...
31 views

### Understanding the SICK S300 RS422 data output

I'm using a SICK S300 safety scanner connected via RS422 -> USB and I'm trying to decode the lines of data into meaningful values, however looking at the data compared to the Telegram Listing it seems ...
44 views

### 360 Continuous Rotation Servo only goes 180 degrees

I bought the following servo: D DOLITY High Speed 360 Degree Continuous Rotation Servo for Robotic(15kg/cm) Metal Gears Servo I'm trying to get it to spin in one direction continuously, but it looks ...
14 views

### AlphaBot2 run / migrate to .NET Core

Bought this robot called AlphaBot2. Has sample code here: https://www.waveshare.com/wiki/File:AlphaBot_Demo.7z What I am interested in knowing is how do I convert these Python samples to C# with .NET ...
39 views

### Calculate ticks with three encoders?

I have a question regarding calculating the ticks in a sensored BLDC. The BLDC has three hall effect sensors with slightly differing phasing and there are 30 magnets in 360 degrees of wheel rotation. ...
40 views

### What exactly is a nodelet?

I am new to ROS. I tried to read the documentation regarding nodelets on ROS wiki. But I couldn't understand it very well. I would like to know what is a nodelets in simple and intuitive terms
24 views

### Autonomous quadcopter: How to transform setpoint into motor inputs?

I would like to know how to transform a setpoint to inputs for the motors of a quadcopter. I would like a function like that: ...
25 views

I am new to the art of building quadcopters and am looking to build a camera platform with a payload of 250g. With the following setup would that be possible or could someone point me in the direction ...
29 views

### teleop_twist_joy with Logitech F710 Joystick force feedback error

I am using a Logitech F710 joystick game controller in ROS Kinetic Kame. I was able to perform jstest testing, and can see my joystick works well. But when I try ...
27 views

### Path planning algorithm to run my floor cleaning robot/zig zag path travel

I am creating a floor cleaning robot with obstacle detection as my final year project. The basic task of the robot is to clean the floor while avoiding obstacles using an ultrasonic sensor. The ...
21 views

### Problem with moving heavy computation into ISR's (dspic33E)?

I am controlling a robotic system using a dspic33E. I have a few PID control loops for motor control, several SPI slaves, and an I2C master that I communicate with. Currently, I use interrupts for ...
30 views

### Variables that Improve SLAM

I have a general question regarding SLAM as I am not an expert on the topic. What are the variables that can improve map generation? The ones I can think of are: A higher resolution camera ...
17 views

### Decrease minimum depth of a RGBD camera

I have a Kinect camera which has a minimum depth of 0.5m and I'm trying to find a way to decrease it to around 0.2m for near-depth detection. Does anyone know how this can be done? Can a macro lens be ...
50 views

### What is the purpose of these grey balls on the drone?

Are these used for position tracking? Are there any papers
27 views

### Relation between PWM frequency and torque

I am using Pololu G2 18v15 to drive a maxon motor. The motor is supposed to drive a load in a sinusoidal trajectory against gravity with maximum torque of 0.0634 NM with max speed of 5 rpm. I am using ...
17 views

### Selection of motor and Calculating the torque for 6DOF robot Arm

I am trying to select the motor for a robot arm with six degrees of the freedom robot arm. What should I do to select the motors and which type of motor I should select?
53 views

### How to synchronise data for fusion in Kalman from multiple sensors with different timestamp information?

I'm using Kalman filter to track the position of a vehicle and receive position data from 2 sensors: A GPS sensor and an Ultrasonic sensor for which I want to implement sensor fusion into the Kalman. ...
41 views

### Null space of the Jacobian matrix for a robotic arm

I have doubts on how to find all the joint velocities that don't produce any linear velocity, so are in the Null space, when we are in a singular configuration. For example, suppose we have a 2R ...
73 views

### Why is behavior-based robotics not as popular as deep learning or reinforcement learning?

I am a master student in Germany and one of our professors is doing robotics research but with a different paradigm - the behavior-based robotics based on Subsumption Architecture developed by prof. ...
31 views

### Data structure to store a robot map

I'm studying robotics at the university and I have to implement on my own SLAM algorithm. To do it I will use ROS, Gazebo and C++. I have a doubt about what data structure I have to use to store the ...
9 views

### ROS rqt_plot and rqt_multiplot font change

I am trying to plot my gazebo simulation data in rqt_plot or rqt_multiplot. However, after plotting is done I would like to change the font size/style on the plot. So far I could not find a way how ...
78 views

### Inverse kinematics of a sun tracker with swapped axes

I am realizing a sun tracker based on latitude, longitude, and date-time. The system calculates the azimuth and elevation angles to track the sun. In a classic sun tracker, the azimuth axis is ...
33 views

### For what step disturbance value the system will become unstable?

I am new to control theory and have difficulties about this question R is the input, Td is the disturbance, C is the output Given that G1=K/(s^2+A*s), where K is the gain and A is a parameter greater ...
20 views

### Working with large bag files efficiently

I'm running into issues playing large rosbag files (over 50 Gb which exceeds my RAM size) consisting of several chunks using launch file. It seems that the file is processed sequentially in chunks, ...
16 views

### How to make x variable change each time and read its value from txt file

I am working on my undergraduate project and this is my first time in using use python to control parrot bebop 2 drone and use BCI or BMI technology. I have x variable (int) and I want to read its ...
35 views

### End-effector orientation is off for certain orientations

I'm using PyKDL's Newton Raphson IK solver to orient my end-effector along any arbitrary direction vector. From the way I've defined my coordinate system, the more parallel the direction vector is to ...