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14 views

Relative pose of 2 sensors in rigid body

I have a robot (gray box in the picture) that I can rotate in 3D (x, y, z) relative to a center of rotation. Let's say that this robot has two sensors with fixed poses in the robot: One IMU that can ...
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0answers
18 views

Simple plastic welding machine

I'm doing a little hobby project where I want to weld two thin plastic sheets together, using two heated plates with a specific pattern. I was doing this manually but felt that the result was ...
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0answers
27 views

How to calculate relative rotation between two IMU's

I'm trying to obtain the relative rotation between two IMU's. In order to verify the quality of the orientation delivered by the IMU (quaternions), I attached both IMUs to a rigid body (bar) but ...
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1answer
29 views

How do you write unit tests for robotics related software?

In my case, I have a library handling 3D input data and want to write tests in order to make sure that my coordinate transform chains for getting the 3D points from A to B are correct. The problem I ...
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0answers
23 views

Robot Localization - Motion and Sense Probability

I'm currently taking Udacity's AI for robotics course and came across a question that stumped me. The problem plays on localization probability given uncertainty in our measurement updates. The first ...
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1answer
41 views

Dexterity calculation with dual quaternions

How can the manipulability of a robot arm be calculated when the kinematics are described with screw theory such as dual quaternions? These methods are sigularity-free, but what could we say about ...
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0answers
20 views

get position of objects using ir

I originally wanted to make a shoddy vr system with two IMU's in two seperate right and left controllers, which their values could be sent over wifi to the game service unity so I can plot their ...
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1answer
18 views

Difference between constant curvature kinematics and rigid link kinematics

What is the difference between constant curvature kinematics and rigid link kinematics and what is their respective definition?
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1answer
27 views

Where do matrix A and A transpose come from in calculating the predicted covariance matrix?

I don't understand where the matrices A and A transpose come from in the equation in this series. I have done a one-dimensional ...
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0answers
5 views

Difference between observed errors and this error matrix in kalman filter?

I have been watching this video series to try to understand the kalman filter. The instructor has this layout explaining the process. What I don't understand is the difference in the error matrix <...
1
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1answer
38 views

Jacobian to determine the linear velocity of each node (DOF 3 RRR robot arm)

I've done the FK and IK for this robot: On those I seem to be able to get to the positions I want on the simulator so I'm assuming nothing is wrong with my FK and IK calculations. I've tried to ...
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0answers
12 views

What is the dynamic model of a biped robot in double support phase?

I would like to know What is the dynamic model of a biped robot in double support phase? As drawn in Fig.b and Fig.c. I have already known (partly) how to model the single support phase drawn in Fig....
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1answer
42 views

Inverse Kinematics with Orientations

Let's say I have a robot consisting of a base $B$ and a manipulator $M$. The pose of the manipulator can be expressed as the transformation matrix $T_{BM}$. I also have a goal $G$ which I want to move ...
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2answers
39 views

OpenCV4.2 and Ubuntu16.04 with python2.7?

Summary: I'm using new vision of opencv, opencv 4.2 with ubuntu 16.04 and python 2.7 After built cv_bridge, the output is: ...
1
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2answers
59 views

Controlling the pose of a manipulator using inverse kinematics

I want to control a robotic manipulator in Cartesian space, using inverse kinematics. I know that I can do this using $\omega=J^{-1}v$, where $\omega$ is a vector of joint velocities, $J$ is the ...
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2answers
25 views

Measuring a Motor's Internal Temperature

As a final safety measure regarding some high wattage motors, I want to measure their temperature (either internal or surface) in live time so that I can automatically kill the power if it crosses a ...
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0answers
41 views

From an end-effector trajectory to joints movements

let's assume that our robot consists of 3 degree-of-freedoms. In order to move the end-effector of this robot along a straight line, these 3 joints have moved as below: Now, if the desired end-...
0
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1answer
13 views

ROS Network configuration on multiple machines - Publisher and Subsciber

I am trying to set up a simple and listener talker across two machines connected on the same wifi network. Machine A has the 10.42.0.89 address and is running the roscore and another node that ...
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0answers
18 views

Caculate/Specify the covariance matrix for a omniwheel robot

I have an omnidirectional robot (x, y and rotation around z), which I would like to use the SLAM-algorithm from ROS. But the odometry from the robot has a drift, which makes some error. To improve the ...
1
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1answer
101 views

Conveyor Belt Calibration for a Robot - Rotation Matrix

Short Question: As demonstrated in the image below, how can I calculate the rotation matrix that relates the base coordinate and the rectangle coordinate, given 3 known points P1, P2, P3 on the ...
0
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1answer
34 views

what are shoulder ball and socket joints called? (i am trying to design and build a hydraulic assistance mech suit)

I'm having problems finding the right sort of joint for my shoulder connection. It is a flat surface on the side of the mech body and I need to create a joint with maximum movement rotating: up, down ...
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0answers
31 views

Quaternionic feedback for for cartesian impedance control

I've seen that there are plenty of ways of generating orientation errors with quaternions. But the one I've seen most often is the following: For example, say that for a quaternion $Q = \{\eta, \...
0
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1answer
47 views

SLERP velocity and acceleration (3d Orientation interpolation)

Hey guys I am quite new to quaternions and I am a bit unsure as to how to use them. How are the velocities and accelerations trajectories determined using quaternions? I have been using slerp to ...
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3answers
36 views

How to avoid false encoder counts due to vibration in robot?

I have a couple of motors on my mobile base other than the drive motors, and they tend to create vibration in the robot. When these motors are turned on, the wheel's encoder ticks increase without any ...
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0answers
15 views

Rotate the end-effector around its Xf axis

I am working on a 7 DOF robot (7 rotational joints). I used euler angles to let the robot point down. Zf (Z of the last frame "end-effector frame") is the direction of the end-effector. What I want to ...
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2answers
43 views

Understanding Twists as 3D Velocities

I am just learning about twists to represent 3D velocities (e.g. of a robot's end-effector), and I have two questions: 1) Wikipedia defines a twist as "an angular velocity around an axis and a linear ...
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0answers
13 views

Steering servo goes full lock when PCA9685 is powered via BEC

Short description: my steering servo goes into full (right) lock when my system is wired in the following way: Pi provides power to the breakout board ESC with BEC is used to provide power to the ...
0
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1answer
58 views

How to calculate rotation angle from 3D points

I have 4 3d points(x, y, z). Using these points how can I calculate rotation angle? Consequently, I want to have a 4x4 transformation matrix including rotation and translation information. 4 points ...
0
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1answer
38 views

Feed both position and speed errors to one single PID

I have seen in the documentation of an old subcontractor's product that the controller of a robotic arm joint was basically feeding error position + error rate directly into one single PID. It feels ...
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0answers
13 views

Is it common for 3D LiDARs to require thermal management?

My team had a 3D LiDAR sponsored to us and we were expecting to be able to use it with no issues, but in the datasheet it specifies that performance can suffer once the temperature rises above 50C. ...
0
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0answers
12 views

How to setup CLion for ROS remotely?

I know how to set up CMake and Toolchain remotely using ssh through official wiki. Does anyone know how to configure a remote <...
0
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1answer
29 views

How to represent the Xf axis of the final frame (end-effector) in function of euler angles?

I am working on a robot arm with 7 rotational joints. I can generate the T of any position, what I want to do ist to represent the vector Xf of the end effector frame in the base frame. How can I do ...
3
votes
1answer
41 views

given position and orientation of two coordinate frames, how to transfer a vector from one to another

given position and orientation of two coordinate frames, how can transfer a vector from one frame to another. The position is given in Cartesian space and the orientations in quaternion or Euler ...
1
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0answers
18 views

How to calculate twist and wrench in local and global frames

I am rather new to screw theory and also lost in robotics books' formulas. we have a simulator of a robot arm within Mujoco physics engine and I'm wondering how I can calculate wrench and twist in the ...
5
votes
1answer
62 views

Cartesian Impedance control Damping Design (Double Diagonalization)

In the literature, it is often seen that for a system: \begin{align} \Lambda \ddot{e} + D_d \dot{e} + K_d e = F_{ext} \end{align} A dynamic damping matrix is required for a robot to take ...
1
vote
1answer
29 views

What communication bus is used in state of the art systems to implement a synchronization signal?

I have a robotic system with many sensors that need to have very accurate localization associated with the data they gather. We have a geolocalization system that acquire localization at high speed (...
0
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0answers
30 views

Make a cheap quadcopter with esp201

I want to make a quadcopter controllable with mobile phone. I have an idea and some question. I want to use: Esp8266 ESP-201 for flight control and connect to controller MPU6050(IMU sensor) 4x ...
2
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0answers
23 views

Roomba iRobot Create 2 Open Interface, is there a way to turn off vacuum motor while the robot is docking?

I am able to control every desired aspect of my robot, except for vacuum motor which seems to be turned on for some reason every time I send Seek Dock (code ...
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0answers
20 views

Serial communication of IMU and Encoder arduino code

Pls, I need people to help me look at where I am getting it wrong. I test this code on Arduino ide and got the result I wanted but sending it to Matlab through serial communication, I obtained a ...
0
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0answers
17 views

Why do inverse directions give correct movement?

I am currently working on driving a bot based on the location of a white ball and I find that giving it negative angular movement moves it to the left rather than the right. Here's a code snippet for ...
3
votes
1answer
49 views

Do mobile robots use variable transmissions?

I've built a simple robot that can move. I'm using brushless motors. I've realized that at slow speeds the motors pull a lot of current. I didn't understand the power / current / efficiency charts ...
0
votes
1answer
28 views

how do I decide what is the order of the polynomial I need to use in a polynomial iterpolation for a trajectory?

I am a student studying robotics, and I am focusing on trajectory planning for a robotic arm. In particular, I am studying polynomial interpolation for defining the trajectories, and I am having some ...
1
vote
1answer
37 views

Plotting a Robot in App Designer

I've a robot created with Peter Corke toolbox and I must plot it inside an app (must be in App Designer - Matlab). The problem is that everytime I try to plot it, it makes an independent figure ...
0
votes
1answer
51 views

Estimation of pitch, roll, yaw angles: synthesis of an observer or IMU?

Dear Robotics Specialists, I want to contact you for advice. I am developing a control system for complex parallel mechanisms like what I presented in this thread. Formulas for calculating the ...
0
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1answer
21 views

Raspberry pi libraries for fortran

I'm quite a fan of fortran and I was wondering if there were any libraries to control the GPIO pins in a raspberry pi with it. I find python to be quite slow so I think it is the best option for ...
0
votes
1answer
30 views

Setting up rewards to account for UAV crashes (Reinforcement Learning)

I am working on a project to implement a collision avoidance algorithm on a real UAV. I'm interested in understanding the process to set up a negative reward to account for scenarios wherein there is ...
0
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0answers
16 views

Raspberry pi 3b+: any recommendarion for a tube wind speed sensor for raspberry

I am looking for a tube wind speed sensor compatible with raspberry pi 3 b+. I found some on internet, but i dont know if they are compatible, most are for flying devices, i will use the sensor for ...
1
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0answers
18 views

Degree of maneuverability mobile robot

According to the traditional kinematic theory for mobile robots [1][2] a mobile robot with a steerable wheel and two passive casters presents a $\delta_m=2,\delta_s=1,\delta_M=3$. This is easy to ...
0
votes
1answer
29 views

Computing Essential Matrix from Fundamental Matrix

I have calibrated my cameras using OpenCV. I used cv.stereoCalibrate to get the E, and F matrices. I wanted to do a sanity check to see if the E matrix obtained is ...
0
votes
1answer
24 views

Simulating sensor readings based on an existing Alan Variance Analysis

My goal is to model an accelerometer and a gyroscope based on real hardware. I understand deterministic errors like bias and scaling but the different types of non-deterministic errors are difficult. ...

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