Robotics Stack Exchange
Robotics Stack Exchange

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1500 questions
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2 answers

How much can working with CNC machines teach you about robotics?

I have built a few simple X/Y/Z CNC machines. I've learned about G-Code, motor control, firmware and open loop systems. I see machines like rovers, big dog and factory arms that seem incredibly complex by comparison, yet they don't seem that…
Great Turtle
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Quadcopter degrees of freedom

It might be kind of a stupid question but how many degrees of freedom are there in a typical quadcopter? I say some saying 4 and some saying 6. The difference stands in translation throughout the other 2 axis (horizontal ones). Being strict to what…
FELIPE_RIBAS
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understanding the PID controller

I am trying to understand the effects of P, I and D constants in a PID controller on a system. As far I've understood, P and I make the system 'faster', and D makes it 'slower'(which I read in books), but I don't actually understand what makes it go…
Control
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How to prevent twisting of cables

I am planning to create a motor turret described in this question. But to simplify the problem, I'm thinking of a wind turbine with a generator in the main head that can rotate freely through 360 degrees to face the wind. How would I prevent the…
John Petrak
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1 answer

Differential drive trajectory following control

I have a robot platform with differential drive which knows it's position and orientation. Lets say that the space through which the robot moves is known and it has only static obstacles. The task is to move the robot from point A and heading alpha…
Damjan Dakic
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2 answers

Do servo motor specifications take into account the gear ratio inside?

I am looking at buying a servo motor for a an application that must be able to lift 4-5 lb at a rotational speed of approximately 1rpm. The servo motor listed here http://www.robotshop.com/ca/en/hitec-hs755mg-servo.html states a stalling torque of…
user1084113
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2 answers

Robotic part to dispense candy

I'm a complete newbie trying to build a simple robot that dispenses candy (M&M, skittles, etc). However, since I'm not familiar with the field, I'm having a hard time googling because I don't know the correct terms to search for. I'm looking for a…
Marcos Savoury
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3 answers

Why do current manipulators tend to use 7 DoF instead of 6 DoF?

In theory, controlling a 6D pose (3D position + 3D orientation) would require 6 joints, and - assuming the robot is carefully designed - the inverse kinematics should be solvable for that case. Adding a 7th joint, and still targeting a 6D pose,…
FirefoxMetzger
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7
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Unwanted Arduino reconnect: Servo + Arduino + Python (Raspberry Pi)

I am having difficulty sustaining a connection between my Raspberry Pi (Model B running Raspbian) and my Arduino (Uno) while sending signals from the Raspberry Pi to a continuously rotating servo (PowerHD AR- 3606HB Robot Servo) via Python. I'm not…
root
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How to know the desired orientation of a quadcopter?

I am trying to simulate a quadcopter model on Simulink. I want to implement a PID controller for each of X,Y,Z and phi,theta, psi angles. PID gets the error, as input, which is to be minimized. For the X,Y and Z, the desired values are entered by…
Moayad Hani Abu Rmilah
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ComputerCraft (Minecraft mod) navigation: Collision avoidance and path planning/finding in 2D/3D space

I'm programming Lua for controlling computers and robots in-game in the Minecraft mod ComputerCraft. ComputerCraft has these robots called Turtles, that are able to move around in the grid based(?) world of Minecraft. They are also equipped with…
Lars Gyrup Brink Nielsen
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What are the different types of electric motors?

I am beginning to learn about the hardware aspect of robotics, and in order for a lot of this new information to be useful to me (whether on this site or elsewhere) I will need a basic understanding of the terminology. One thing that comes up…
user453441
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Are Rospy subscriber callbacks executed sequentially for a single topic?

Suppose a ROS node receives new batch of data on a topic while the previous batch is still being processed by callback. Will ROS wait for its completion or will it spin a new thread and run both at the same time? I'm asking because if they are…
Tomas R
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Is there a way to determine which degrees of freedom are lost in a robot at a singularity position by looking at the jacobian?

For a 6DoF robot with all revolute joints the Jacobian is given by: $$ \mathbf{J} = \begin{bmatrix} \hat{z_0} \times (\vec{o_6}-\vec{o_0}) & \ldots & \hat{z_5} \times (\vec{o_6}-\vec{o_5})\\ \hat{z_0} & \ldots & \hat{z_5} \end{bmatrix} $$ where…
joshkarges
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3 answers

How to open a sliding window?

I live in an apartment that has sliding windows in it. The apartment is naturally warm because we live above a mechanical room, such that we either opened the windows or ran the air conditioning through the winter. I want to create a device than can…
Michael Dornisch
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