# All Questions

4,460 questions
24 views

### How to balance a long vertical bar

I have a mobile base (1400x1800x400 mm) which has a vertical bar (1) mounted on its geometric center; this vertical bar has a length of 2500 mm and a diameter of 100 mm and I need to keep it always in ...
37 views

### How do I calculate the direction robot is facing, pose from velocity and yaw rate?

I have a simple car robot with four wheels moving relatively slowly (5~10 mph). The robot has a velocity magnitude and yaw rate sensor and the sensor samples about every 0.1 seconds. I want to map the ...
44 views

### 3D Inverse Kinematics Jacobian Construction

I am following this article: Overview of Jacobian IK From the link, an example says: O is a pose vector which represents the initial orientation of every joint And following this, it gives an ...
43 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 - ...
33 views

### Can't get iRobot Create to respond

We have an iRobot Create connected to a Win 10 PC with the cable supplied with the unit. We have followed the instructions here: http://www.robotappstore.com/Knowledge-Base/How-to-Use-a-RealTerm-...
48 views

### Extrinsic calibration of a multicamera-rig mounted rigidly on a mobile robot

We have a set of 8 cameras mounted rigidly on a mobile robot. The cameras are forming an arc, which allows a 360º vision. I want the extrinsic parameters of them referred to the robot. Is there any ...
7 views

### If you move the RGBD camera to other places on a Turtlebot, same orientation, create a map, does ROS navigation stack with AMCL still works?

I got a Turtlebot, and I’m thinking of putting the RGBd camera to other places. If you move RGBD camera to other places on a robot, same orientation, create a map, does ROS AMCL still works? I am ...
38 views

### Gravity compensation

I am just getting curious about this gravity compensation technique. If we could compensate the force generated by the gravity (by feeding in the exact amount of force into the opposite direction), ...
57 views

### How to transform raw accelerometer data into the Earth fixed frame to determine position

I have data from a TeleMega and do not understand how to apply the rotation matrix for the accelerometer data so that I can get the more accurate position estimate from my accelerometer. My data comes ...
26 views

### How to find Q and R in the Kalman filter according to known noise information?

My team built this linearized model in Simulink which works pretty well. I am currently building a continuous kalman filter. I assume some noise disturbance in the input and the measurement like what ...
37 views

### Have you done take-home robotics(ROS) coding test in interviews?

Have you done take-home robotics(ROS) coding test in interviews? Do you want to share the coding test instructions with me? or point me in the right direction where I can find some to practice? I'm ...
49 views

### How to determine the direction of X-Axis in Denavit Hartenberg process? [Sketch inside]

The rules of assigning axes for DH parameters are (as I know them): 1- Z: in the direction of the axis of rotation/translation of revolute/prismatic joints. 2- X: perpendicular to the previous Z axis ...
36 views

### Difference between Single-Query and Multiple Query Algorithms?

I am spending a lot of time in understanding these two concepts, because in several papers that I read, they define them differently, and I do not know exactly what is the meaning of the two ...
53 views

### 3D Inverse Kinematics Jacobian

I am reading up on inverse kinematics and have a few questions I hope could be answered. This example is from a 3-revolute-joint, where $E$ is the end effector and $G$ is the goal position of the ...
48 views

### How does a self-driving car locate itself when the environment changes?

There's something I don't quite understand about SLAM. When a self-driving car wants to locate itself using a prior map, how does it do that when the environment keeps changing, e.g., new cars parked ...
16 views

### Servo LIneSensor conflict

We are using a Prizm Genuino controller. We have been using a line sensor to successfully detect black lines but we seem to be getting a conflict with our servos now. The lineSensor does not seem to ...
22 views

### TGY-6114MD Servo motor needs push to start

I currently have an inspection robot deployed in a remote part of Africa that has a failing Turnigy TGY-6114MD servo. The issue appeared randomly. The servo won't respond to commands unless given a ...
30 views

### Calculating the cartesian position of each joint with DH transform

Premise: I am by no means an expert on Robotics, I have to deal with this project where we use a robotic arm (franka emika), so feel free to assume that I got the basics wrong! I have this arm ( ...
38 views

### Real world dynamic problem suggestion for PID [closed]

I need you guys to suggest me a problem that requires to change PID coefficients in different times. Lets say every 1 minutes the environment should change and readjust the PID’s parameters. Note that ...
39 views

### Kalman filter to fuse ultrasonic altitude sensor and accelerometer

I'm a little confused on how to set up the Kalman filter matrices to fuse an ultrasonic altitude sensor and accelerometer from IMU. I am trying to implement this for a quadcopter. And what I'm ...
24 views

### Dual vs single ultrasonic sensors

What is the difference between dual ultrasonic sensors (sensors with two round elements) and single ultrasonic sensors (the ones with a single cylindrical sensing element)? What are the advantages/...
21 views

### Max angle of beam against surface (ultrasonic sensor)

I am trying to localize a robot within a rectangular room (182cm x 243cm) with completely black walls (so IR sensors and LIDAR are out of the question). I am trying to figure out if I can position ...
49 views

### LiDAR Point cloud data reliability/quality

I'm trying to develop a quality measurement (kind of a metric) for the reliability / quality of given point cloud data (coming from a 3D LiDAR) at a given point or region. It should come into account ...
22 views

### Omni vs mecanum wheels for drawing robot

I'm designing a mobile robot which will have to draw some lines (straight and/or curly) on the floor while it moves. The floor will always be flat with almost no obstacles. The robot will have four ...
27 views

### Minimum distance for a shaft coupling

What is the minimum shaft distance required to do a shaft coupling. I want to mount encoders on my motors but the shaft length is only 15 mm long. My encoders are 12 mm wide. So, I only have 3 mm to ...
55 views

### Is there a more accurate feedback loop with less overshoot or disturbances than PID?

So I was starting a robotics project and turns out that PID hasn't served very well in the past. So I was wondering if there was another feedback loop mechanism which has less overshoot and is more ...
16 views

### Encoder attached to output of gearbox of stepper motor

I'm building a SCARA robot controlled with stepper motors and want to use an encoder to close the loop. The main reason for this is I am using an experimental gearbox with nonlinearities and zero ...
54 views

### Esc calibration

I want to make a calibration setup for BLDC ESC in the simulink model. I'm using arduino mega (3,9,10,11 pins) and quatro 30Ax4 esc. Normally I can set it to it's max, min, and incrementally increase/...
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### How to use MoveIt and ros_control (from setup assistant) to control Gazebo robot?

I've noticed that in the MoveIt setup assistant, there is a "ROS Control" that auto-generates 2 files: - ros_controllers.yaml - ros_controllers.launch I wanted to ask if it was possible to use these ...
62 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 ...
56 views

I am working on a project that requires training a neural network with humidity and temperature values. After spending a while googling on how to run a neural network on ESP32 (Wemos LOLIN D32 Pro), I ...
40 views

### How a robot could know when it harms a human?

Artificial intelligence and robotics are claimed to be regulated. Experts say they could turn against us. My point is: I assume that robots are not aware of nothing, they're just able to measure ...
21 views

### Setting up CLion for ROBOTC/EV3 COde

I'm using ROBOTC for my robotics projects, but I'm frequently getting annoyed at not being able to autocomplete my brackets and quotes, etc. Also, the color scheme is just... bright, to say the least. ...
8 views

### How to translate individual rotor trust to Wrench object in ROS (force&torque)

I am learning about ros and dronesim Basically following this. There is a wrench object where I can create with force and torque vectors. My question is how can I translate individual rotor trust to ...
23 views

### Obstacle width measurement

On non-lidar equipped rovers, how is the width of an obstacle detected such that it can be avoided? If the ultrasonic sensors are used for obstacle detection, these sensors usually don't give data ...
19 views

### Sending RTCM corrections from u-center NTRIP Server (Windows) to ROS NTRIP client (Linux)

I'm trying to set up an RTK GPS (NEO-M8P) but I need to send corrections using NTRIP. For my initial tests, I installed the u-center application on a Windows computer as my base station and then I ...
17 views

### Tetrix Prizm and ROBOTC

I am currently trying to find if its possible to program a Tetrix Prizm motor controller with ROBOTC? Because I have an EV3 brain connected with the Prizm to a robot assembly with two motors, and I ...
43 views

### How to accurately navigate from one GPS coordinate to another using just GPS & IMU? [duplicate]

I'm looking for ways to accurately navigate from one GPS location to another. I have a GPS sensor and an IMU. I can calculate the distance with the help of GPS I believe and with the help of ...
18 views

### Sensor model and Inverse sensor model using occupancy grid mapping with lidar for particle filter

I'm a bit confused about how one goes about calculating the sensor model $p(z_t|x_t, m)$ and inverse sensor model for position $p(x_t |z_t,m_{t-1})$. From this answer, it seems like one way for ...
46 views

I and my friends are planning to build a dog like quadruped robot. We have designed it like MIT Cheetah Mini like legs structure, each leg having 3 Servos, 3rd DOF for rotation. We have calculated ...
23 views

### How to calculate power supply requirements for Closed Loop Stepper Motors

I have a CNC Router table that has 4 Nema 23 stepper motor (open loop). I want to upgrade the machine and use 4 Neam 34 Closed Loop Steppers. These are the motors and drivers I'm considering: ...
20 views

### Using Ov7670 with Arduino Mega

How can I use arduino mega and a OV7670 module to recognize the three letters A,S and H which are on the wall with special font "Arial Black", I need the camera module to work simply as a sensor if it ...
20 views

### Get a signal from position array data

I'm working with position data from a hand sensor, and need to apply an FFT to it to get the level of tremor based on the frequency of the signal. I get two arrays, one with +1000 frames of position ...
29 views

### Jacobian of $(\textbf{e}^{[\boldsymbol{\xi}] _\times}\textbf{T})^{-1}\textbf{p}$ wrt $\boldsymbol{\xi}$

The chain rule is always confusing. Is the following derivation correct? \frac{\partial (\textbf{e}^{[\boldsymbol{\xi}] _\times}\textbf{T})^{-1}\textbf{p}}{\partial \boldsymbol{\xi}}...
40 views

### Add control and planning trajectory to double pendulum [closed]

How do I control a double pendulum to get the end effector link to go in the trajectory shaped in a perfect circle? I have the equation of the circle to go in but I don't know how to get the double ...
42 views

### How to get constant motor RPM regardless of battery voltage?

I have a brushless motor with a propeller attached, driven by an ESC and a LiPo battery. I noticed that as the battery level drops, the motor spins slower, which makes sense. My question is is it ...
44 views

### Help with Probabilistic Robotics Equation 13.22 detailed derivation

Equation 13.22 from Probabilistic Robotics below: Here's how I get from first line to second line:  p(x_{1:t}^{[k]} | z_{1:t},u_{1:t}, c_{1:t}) = \frac{p(x_{1:t}^{[k]}, z_{1:t},u_{1:t}c_{1:t}) }{ ...
40 views

### Sensor fusion to calculate joint angles between segments of a robot arm using IMU data

I have an IMU attached to each of the segments of a robotic arm, which gives me accelerometer and gyroscope data. My goal is to first of all improve the quality of the sensor readings and subsequently ...