# All Questions

4,435 questions
64 views

### Are robotics competitions for beginners available?

The micromouse challenge was done since the 1980 in the context of university driven robotics research. The Robocup challenge has a similar approach and provides a competition for university students. ...
26 views

### State-vector for distance measurement between two autonomous cars

I hope someone can help me: Given two autonomously driving cars, I want to make sure they keep a constant distance to each other. For this purpose, I want to design a Kalmanfilter. Typically, the ...
18 views

### Subscriber to array type overwriting data from different publishers!

I have been witnessing some bizarre behaviour with my very simple node. I have a custom message that contains uint8[] type (it's 8 elements long). I have a ...
45 views

### Setting up a Structured Light Stereo system

I am trying to get started with a stereo experiment and wanted to know the mistakes I might have made during the experiment. The goal is to calculate the depth map of an object using one light ...
20 views

### Maximum value of norm of mass matrix M

How do I compute the maximum values for ||M(q)|| and ||M_dot(q)||, the induced 2-norms, where M(q) is the mass matrix from the standard dynamical model of a robotic manipulator. I have the numerical ...
34 views

### help to find the bug for calculating inverse kinematic using jacobian

I am calculating inverse kinematic for 5dof robotic arm using Jacobian matrix (first time). i used following formulas to do my calculation and also implemented in my code. for more information please ...
37 views

### Why no cmd_vel topic when running Turtlebot simulation on ROS + Gazebo?

I have been having a very difficult time trying to understand why my system does not have the cmd_vel topic. I am trying to get a ROS system running with Gazebo so that I can work through tutorials ...
44 views

### How to tell if a stepper motor position is moved by external force?

I'm designing a round knob positioned by a stepper. The knob is intended move by an external force while positioned by the stepper. I'd like the stepper to release (power off) when the knob is ...
54 views

### Open source robotics projects that have complex software structure?

I've built some robotic systems that rely on handcrafted hierarchical FSM, I'm hoping to learn more by studying codes from some open source system that have more complex structures. Can anyone point ...
35 views

### Image data fusion

I have three cameras separated by some distance, looking at a scene. I have calibrated them using checkerboard and I have their respective intrinsic parameters and their pose and rotation matrix, I am ...
39 views

### constraining rotation in jacobian IK algorithm

i'm implementing a damped least squares IK algorithm for an articulated arm, based on the work here. I have the algorithm working well, but it occasionally produces solutions that have segments ...
52 views

### Self balancing robot: PID Control Algorithm

I am working on a hobby project for self balancing robot. My robot balances quiet well, so my next step is to start moving it. I saw in some blogs that they used a cascade control algorithm as shown ...
27 views

### Turning a 2 wheeled robot 90°

i got a task for which i need to drive a certain distance and move around an object. I finally managed that my robot goes almost straight but i think its enough. But now i gotta tackle the problem how ...
24 views

### Vertically moving robot

I want to build a 4WD robot that can travel vertically by pushing against opposite rails. The wheels push against the rails and generate friction, the robot moves upwards as the wheels rotate. This is ...
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### Forward Kinematics with matrices

From the image, I would like to find out how joint 1, 2 and 3 can be computed by using forward kinematics? (Assuming a theta value was given) I understand that to get point 3 to origin (...
29 views

### Connect 2 motor controllers

i have programmed for my two wheeled robot 2 separate controller for each wheel so that afer approx. 1 second both motors reach my desired speed. But my problem is that one of those motors is faster ...
35 views

### Swarm Robot Simulation

Both V-rep and Webots simulator says that they can simulate multiple robots. Is these simulators are capable for simulate swarm robots? Can I simulate the swarm intelligence algorithms like ACO, ...
34 views

### How is the IMU used in the PixHawk?

Looking at 3DR's Pixhawk hardware on GitHub the FMU and IMU are treated as different pieces of hardware. On the schematics for the FMUs (example) there is limited reference to the IMU. So, is the IMU ...
45 views

### Hand eye calibration of robot arm using a 2D camera and marker of known size

If my understanding is correct, one flavor of hand eye calibration requires the following pairs of data for different robot arm positions: The transform from the robot base to the robot hand. The ...
39 views

### Difference between Collision Cone and Velocity Obstacle

I'm trying to understand these two classic approaches to path planning in dynamic environments/with moving obstacles. According to some review papers, there seems to be quite a difference between them,...
21 views

### Tackling loops and discontinuations in PID line follower

We are making a PID line follower using arduino for a competition. According to the rules of the competition they will have loops and discontinuations in their track. Can anyone give some idea how we ...
27 views

### Fixed-Delay Kalman smoother with/without augmented measurements

There are several algorithms regarding fixed-lag Kalman smoothing. In most cases, an augmented state vector is defined in which the elements are the current and delays of the original state vector. ...
22 views

### How to determine the Process- and Measurement Noise Covariance Matrix of a Kalman Filter

I'm stuck with the following problem: In a Kalman Filter, we assume the following holds: The state vector can be filled with values which are returned by actual sensors. The Transition matrix needs ...
29 views

### Rotating two things on the same axis

I'm working on a project where I want two separate shafts to be in the same place. Think of it like a clock where the hour and minute hands move independently. Also like a clock, I want the motors and ...
25 views

### Convert sonar scans to Lidar scan file

Has anyone tried to map environments using Sonars or 1D ToF sensors? Since it's very difficult to implement such an algorithm from the scratch, I'm planning to use an existing ROS packages such as ...
97 views

### Quadcopter motors vibration problem

I built an Arduino Due based quadcopter, with MPU-6050 for auto levelling and BMP-085 for Altitude. I am using Kalman filter code from here for the MPU-6050 to take the Roll and Pitch angels from the ...
51 views

### Path planning of wheeled robot [duplicate]

let's say the robot Looks like this (an usual robot arm with 4 wheels) : In this case as far as I know, the idea of path planning is just to compare the actual position x with the desired position ...
36 views

### How can I determine the Transition Matrix of a Kalman-Filter ?

I am trying to set up a Kalman-Filter to filter position-measurements of a self-driving car. To do so, I consider a state-vector with 5 elements and am now trying to set up the Transition Matrix. As ...
39 views

### Control System Analysis - Block Diagram Basics

Why this relation is not right? C(s) = R(s) * [G(s).G(p)+D(s)] / [1+G(s).G(p)+D(s)]
41 views

### Power systems design for a vehicle

I'm designing a system to power up my vehicle with 12vDC and I have 8 motors each draws 25A at max and they are not expected to work always at the same time, meaning that in the maximum case 6 of them ...
33 views

### How to keep track of (x,y) co-ordinates of a line-following bot?

I am working on a bot that follows a certain line path based on some pre-determined algorithm. I would like to know what the (x,y) co-ordinates of my bot are as it traverses with respect to some pre-...
69 views

### Robot moving on a flat floor - 2D or 3D SLAM?

What is the best way to model the SLAM problem (offline) for a wheeled robot moving on a flat floor in 3D space (the pose has only 3 degrees of freedom)? In terms of sensor data, we have the wheel ...
42 views

### Wrong forward-kinematic after calculating from DH-parameters

I'm working on an exercise about DH-parameters for my robotics course in university and I ran into a problem, because my solution is different from the one given by my professor. I calculated the DH-...
22 views

### Writing IMU accelerometer data into as twist messages into cmd_vel

I am reading accelerometer data from the wiimote /wiimote/state topic. A sample of the data I'm working with is as follows: ...
24 views

### motor selection for farm rover

I'm designing a rover to use as a harvest aid on our vegetable farm. It will be GPS guided using an RTK base station to straddle our parallel fixed-width vegetable beds. (66" wide with 48" of growing ...
14 views

### Pwm settings of a Sg90 servo motor

I use a TowerPro sg90. 1.5 ms for the centre position 0 degree, and 2 ms pulse for +90 degree and -90 degree with a 1ms pulse. But it's definitely not looking like it goes for 90 degree or -90 ...
30 views

### Kalman-Filter: how to solve angles near +/-pi?

I'm trying to get into Kalman filters. I've noticed an issue with Euler angles near -180°/180° (or -pi/pi) and wonder how to correctly resolve this. Its often said you need to normalize the angles ...
14 views

### AWS Robomaker - success story?

I've struggled to get my head around Robomaker and still have not gotten even a simple robotic example to work. Have you located any documentation that is more complete than one Amazon offers?
31 views

### How to create a .urp for universal robots?

The polyscope platform of Universal Robots saves programs as *.urp. They are very different to urscrips. Is there a way to create such files without polyscope?
110 views

### Struggling to understand Jacobian Inverse Kinematics

I'm trying to find a method to control a moveo 5dof arm. My goal is to calculate the right angle to turn for each stepper motor to reach a desired point in real environment. I've spent time looking at ...
22 views

### how to normalize PWM if the value exceeds the maximum speed limit

I have implemented inverse kinematics for nonholonomic mobile wheeled robots, and the RPM range of the motor that I used is -50 to 50, while for PWM is from 1300 to 1700. But in certain cases, the RPM ...
19 views

### Torque Disturbance Observer for Manipulator Arms

Is there a tutorial/guide apart from the research papers ( paper 1 and paper 2 ), for implementation of torque disturbance observers on multi-DOF robotic manipulators to determine sudden collision ...
27 views

### how to find space in point cloud larger than given l*b

Is their any method by using which I can find a space or gap in given point cloud which has size greater than given rectangle of size $l*b$ or a circle of radius $r$? This way my robot can make a path ...
37 views

### how to introduce 2 inputs into a matlab block function that processes only one variable at a time? [closed]

Using SIMULINK, I wanted to optimize 2 variables with the ant colony optimization algorithm; which is written in a matlab function block, the function is of type function y = f (x) it has only one ...
29 views

### PID Tuning. Does Setpoint Affect Gain for Tuning

So I understand that a heuristic way of determining values for PID would be to use the Ziegler method, having zero I and D and then adjusting P until you have oscillations. Wouldn't the setpoint ...
18 views

### setting custom variables on catkin workspace environment

I am developing a package for the ROS, in fact it is a package of resources / models for the Gazebo, and I need with the presence of this package in the Workspace of Catking, to be automatically set ...
75 views

### Encoder values for pid control

Im working on a two wheeled robot and im trying to implement a pid control for the motors. But i have a problem, all sources i found online said i have to calculate the error with my encoder values. ...
91 views

### Relationship between the velocity twist Jacobian and the spatial velocity Jacobian

While reading Kevin Lynch's "Modern Robotics" [1], I came across a fundamental question concerning the manipulator Jacobian. Upon better reading and further cross-checking with Peter Corke's "Robotics,...