All Questions

1
vote
0answers
12 views

Problem with UKF weights when calculating predicted state

I'm having troubles implementing a UKF during the calculation of $\overline{\mu_t}$, specifically in this step: $$\overline{\mu_t} = \sum_{i=0}^{2n}w_m^{[i]}\chi_t^{*[i]}$$ My problem I'm facing is ...
0
votes
0answers
21 views

I need to read a lot of analog signals without any analog pins

I have an nvidia xavier with gpio running linux. It should work very similarly to raspberry pis. I need to connect a bunch of pressure sensors, thermistor, potentiometers, and vibration sensors to my ...
0
votes
1answer
23 views

Accuracy of hall sensor encoders on Raspberry Pi

I have 2 motors (JGA25-370) with hall-sensor encodes. They emit about 90-100 interrupts every 100ms, so 1000 a second. Which means I have an interrupt happening every 1ms. The motors are driven by ...
0
votes
0answers
22 views

Combining data from 9DOF IMU

My team and I are building an AUV and are planning to replace the existing 6DOF MPU-6050 sensor with a 9DOF Adafruit BNO055 sensor. However, we're unable to figure out how to combine the data from the ...
0
votes
1answer
33 views

Which sensors can be used to feel breeze blowing by the robot?

Am faced with a situation where my robot needs to feel breeze blowing by over its artificial skin. While there exist many types of tactile sensors, nothing seems to fit the bill. I might abandon the ...
1
vote
1answer
32 views

How many encoders should I have?

I'm planning a robot vehicle and plan to get one or more motors that have encoders built in. How many encoders do I need I really need in order to gather solidly accurate information about speed ...
1
vote
0answers
36 views

How to calculate observation matrix Jacobians in EFK based mono slam? What are projection Jacobians?

I have been trying to understand an implementation of monoSLAM 1. But my question is generic to EKF based single camera SLAM. My Jacobian calculation leads to complex and lengthy expressions while ...
-2
votes
1answer
48 views

Why can't motors be as elegant as human muscles? Why do we have to use electromagnetism to create movement?

Pretty much as the title says. Why isn't it possible to build motors as microscopically and simply as they're built in humans? Why can't we recreate electronic nerves and muscles?
1
vote
1answer
41 views

FastSlam2.0: ICP Scan Matching vs Odometry? What is the typical time step?

When working with a FastSlam2.0 algorithm, ICP Scan Matching is supposed to give more accurate measurements than odometry. The problem is, that given some noisy measurements from the laser scanner, ...
0
votes
0answers
20 views

message_filters doesn't call the callback function

I'm trying to use the message_filters in order to subscribe to two topics. Here's my code ...
2
votes
1answer
57 views

How can I preserve a high framerate while using at least 1280x720 resolution on 2 USB cameras on the same computer?

To expand on this, I have a down-facing camera using the whycon ROS node on Ubuntu 16.04 Kinetic on a quad-core computer with 640x480@60fps MJPG video. I'm also using the ...
0
votes
1answer
125 views

Convert local coordinates of a moving IMU to global coordinates

I am trying to compare the performance of an IMU in motion against an optical tracking system. The IMU has an accelerometer and a gyroscope and gives output in the local IMU coordinate frames. The ...
0
votes
1answer
46 views

Quaternion error in one degree of freedom

I would like to control a system which orientation I measure with as quaternion based EKF in one degree of freedom. Obviously the simplest thing would be to convert the quaternion estimate to euler ...
0
votes
0answers
18 views

Compile webots for Python 3.6 for Windows

I would appreciate if someone could assist me in compiling webots source for Python 3.6 to allow me and others to use TensorFlow with it. I already tried but apparently there is something not ...
0
votes
2answers
43 views

ABB Object Oriented RAPID language

How do I create something like a class and have instances of it in ABB RAPID language?
1
vote
2answers
60 views

Microcontrollers and Python

So I am fairly new to robotics however I do have some background with the python coding language. Recently I set myself the task of learning some basics for robotics just to increase my knowledge base....
0
votes
2answers
52 views

outdoor autonomous robot [closed]

i had search over google and found out more or less some sensor that i could use like sonar, gyroscope, accelerometer,magnetometer and gps and 2d lidar (which is less expensive, around $300) i have ...
2
votes
1answer
57 views

extended kalman filters, linearization of output

Say, we are dealing with an odometric localization problem. In the below example, $(x_k, y_k), (x_l, y_l)$ are cartesian coordinates of the sensor and the landmark respectively. Then the output ...
0
votes
1answer
36 views

What are the differences between wheel and manipulator joint encoders?

As far as I understand the joint encoders output the angle and the wheel encoders output speed. Is that accurate? In either case, how do the differences affect the kinematic calculations, as in path ...
0
votes
0answers
11 views

How can I import openmv camera feed in MATLAB

I am planning to use openmv camera with wifi shield for my project. I want to import the video feed to MATLAB for further processing. As per my preliminary search it is extremely difficult and ...
-1
votes
1answer
55 views

Is robotics and automation a contradiction?

With the Meccano toy it is possible to construct a variety of useful machines. For example a knitting machine, a loom or a steam engine. What these machines have in common is, that they are doing ...
0
votes
1answer
46 views

How should I power my servo motor with the Adafruit PCA9685 chip?

So I have an Adafruit pca9685 controlling an HSB-9380TH servo and a MG-996R servo. I recently began learning about building robot so I apologize if these questions seem dumb. I literally spent a days ...
1
vote
0answers
39 views

Path Planning for Spherical Wrist (RRR)

I have found the inverse kinematics of a spherical wrist. The wrist is not attached to any other type of arm, it is the sole controller. Based on this IK solution, how can I generate a path plan for ...
0
votes
2answers
30 views

Identify contacts on wires of an electronic speed controller

I have got an electronic speed controller as pictured in the first image. What kind of contacts are those on the left? The second image is a closeup. edit to clarify question I am asking how to ...
3
votes
1answer
49 views

Input/output linearization

I am studying the book "B. Sicilliano -Robotics. Modelling, Planning and Control" chapter 11, Input/output linearization topic. Where does the formula for theta in 11.75 come from? In the case of the ...
0
votes
1answer
30 views

Humanoid robot with Raspberry pi [closed]

I am in the midst of designing a humanoid robot, and I am very new at this technical stuff, but I have found servo motors which are capable of producing 500 kg.cm. Now I am looking at making a ...
0
votes
2answers
52 views

I must determine the resolution of a control system when using an 8-bit encoder for a single-rotation joint

The length of the link is 50 cm and the arm moves 180 degrees. Can anyone help me? Out of the cosine theorem, $d = \ell \sqrt{2\left(\ell-cos\right)}$, I calculated the distance traveled by a linear ...
0
votes
2answers
59 views

How a quadcopter pitch/roll impacts thrust?

I'm thinking about how a quadcopter flight controller works, and I usually see that each motor speed is determined by a formula like: ...
1
vote
3answers
184 views

Inverse Kinematics Problem of Articulated Manipulators Arm

I have a robotic arm consist of three joints (servomotor for each joint), as shown in the figure below: Notes: Each servomotor rotates around 180 degrees. The angles of the theta2 and theta3 ...
0
votes
1answer
29 views

Powering servos for quadruped spiderbot using arduino uno [closed]

I am using 12 towerpro SG90 servos. What battery should I use for powering 12 servos for my arduino uno? Can i use the 12v battery, plug it in to 12v dc jack of arduino and tap the 5v output of ...
7
votes
2answers
161 views

Singularity problem at Inverse kinematic solver

I am struggling with this problem for days. I really hope that someone could give me a hint what the problem is. The robot consists of 5 axes. The first axis rotates around the z-axis and other 4 ...
0
votes
0answers
13 views

Mindstorms: EV3 Brick files vanished

The EV3 brick turned off by itself (the battery is not low), we restarted it and the file finder was empty, all our files are not there right now. Have they disappeared from the brick forever or is ...
1
vote
0answers
46 views

Defining C-space state for an arm in OMPL

I'm very new to Robotics, so please bear with my ignorance about the subject. That said, I'm trying to use Open Motion Planning Library (OMPL) to set up the configuration space for a robotic arm ...
2
votes
2answers
106 views

What are the equations of a s-curve position path?

I have a decoupled mechatronic system with two motors. I want for each motor to give a s-curve path as reference. You can see in the image below the position path, velocity and acceleration. All ...
-1
votes
2answers
79 views

how to control servo motor with potentiometer in arduino

I'm working on a robotic arm which uses 3x MG995 servo motors, 3x potentiometers (10k), and 1 Arduino Uno. I uploaded the code to the Arduino but the servo won't stop. I want to control it with the ...
1
vote
1answer
64 views

Does MIT Cheetah uses Series Elastic Actuator?

I have been wondering does MIT cheetah purely only use electrical active compliance on it's robot or did they use a Series elastic actuator since they have this webbing tendon?
1
vote
0answers
32 views

Stereo-Calibration with Variable focal cameras

Is it possible to perform stereo-calibration with cameras having variable focus? and if so, how is it done basically?
2
votes
0answers
21 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 ...
1
vote
1answer
39 views

turning a roomba 980 into a create

I have an old 980 that I want to turn into a create. Is this possible? I've seen some posts that seem to indicate that it is, and I'm wondering if there are any more up to date instructions on how ...
1
vote
0answers
62 views

URScript - how to get the actual TCP pose in tool space coordinate system?

I am writing a simple script for universal robots UR10 robotic arm. I am trying to find a way to to see if the tool current position is outside of a 3D bounding box. the 3D bounding box is defined ...
1
vote
1answer
36 views

Representation of 2D coordinate space with orientation

I wanted to know what is the mathematical representation of 2D coordinate space with orientation in the same plane. 2D coordinate space is represented as $R^{2}$, how do I include orientation in the ...
3
votes
3answers
85 views

State Space model for bouncing ball

In lecture 5.5 Bouncing ball, slide 26, Coursera's Control of Mobile Robot course, how are the state space equations formed in "Equations of motion in-between bounces"? Why is [0 -g] added? And how ...
1
vote
1answer
175 views

Is rospython subscriber thread safe?

I'm trying to write a python node, which has one class and two member functions as callback functions. so a TimeSynchronizer and Subscriber in a node. I saw in this link and tested that python ...
0
votes
2answers
75 views

Libraries to simulate path planning in a dynamic environment for a 2D space

I need to simulate a path planning approach for a 2D space where the obstacles are moving. Initially, I need to implement probabilistic road map, D* lite, A* and Bug2 algorithm. The robot needs to be ...
0
votes
1answer
42 views

Arm path planning with obstacle avoidance in Unity

My application is not specifically in Robotics, but the problem that I'm trying to solve seems to have been studied primarily from the viewpoint of Robotics, so I am hoping to get an answer here. ...
0
votes
1answer
33 views

How can i find and install (acspid) python PID library

How can i find and install (acspid) python PID library in the folowing code import acspid pid=acspid.pidcont(1.2,0.02,0.01,5,-5)
0
votes
0answers
18 views

Can I combine BEAM robotics with fuzzy control?

Beam robotics invented by Mark W. Tilden is about analog circuits for controlling robots. The idea is to avoid microcontrollers and software and use instead resistors, breadboards and capacitor for ...
-1
votes
1answer
24 views

Localization in box using rangefinders

Let's say I have a robot, located in a box. The robot can move in the x and y and rotate. The robot has 4 rangefinders, mounted 90 degrees apart, that measure the distance to the walls of the box (I ...
1
vote
1answer
109 views

Inverse kinematics for differential robot knowing linear and angular velocities

I have a differential robot and I am using ROS to run it. When I need to move the robot, I can send commands to it, specifically linear X and angular Z velocities. Linear X is in m/s whereas angular Z ...
0
votes
2answers
166 views

How do I find the inverse kinematics of a 5-DOF manipulator having the following DH parameters?

alpha = [ -90, 0, 0, 90, 0] a = [ 0, 400, 200, 0, 0] d = [63.5, 0, 0, 90, 100] I am trying to calculate the joint angles but I am stuck ...

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