Robotics Stack Exchange
Robotics Stack Exchange

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1500 questions
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2 answers

How to tell a stepper motor's position, or detect slippage

I am creating a CNC machine on a budget, using old motors out of printers/scanners/etc. I am limited to about 650mA for the whole system, so my fear is that when the cutting bit touches the material, the stepper might be moving too quickly and…
Anonymous Penguin
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Shape Memory Alloy wire for robot gripper arm actuation: How to vary grip pressure?

For a robotic gripper arm we are designing for factory floor use on very small components, we propose to use electrically activated Shape Memory Alloy (SMA) wire harnesses for actuation. The device being designed is akin to Pick & Place machines…
Anindo Ghosh
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What's the difference between feedback and feedforward control?

I'm reading from Astrom & Murray (2008)'s Feedback Systems: An introduction for scientists and engineers about the difference between feedback and feedforward. The book states: Feedback is reactive: there must be an error before corrective actions…
Paul
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Multiple control loops with overlapping effects

I'm familiar with using PID to perform closed loop control when there is a single output and a single error signal for how well the output is achieving the desired set-point. Suppose, however, there are multiple control loops, each with one output…
Dan Bryant
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3 answers

Can RC servo motors continually rotate?

I know that RC servo motors are designed for precise movement, rather than a D.C. motor's continual rotation. Are most RC servo motors limited to movement within one rotation or can they actually be made to continually rotate? That is to say, is…
Greenonline
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How do I decide the size of the time steps between sensing and control actuation?

My Background: My experience is in solid mechanics and FEA. So I have zero experience in robotics/controls. Problem Description I'm developing a control strategy to stabilize a complicated 6-legged dynamical system. Torques Ti from each leg's…
Guy
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9
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1 answer

How to balance a flying quadcopter?

I'm using my own code to create a quadcopter robot. The hardware part is done but I need to balance the copter. The original video demonstrating the problem was shared via dropbox and is no longer available. I have tried to play with the speed of…
user697
9
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2 answers

Adding an Actuator or Force to a (Featherstone) Articulated Rigid Body Model

I'm working on a project where I need to model a system that is essentially comprised of a series of ball-and-socket joints attached to a base, which is attached in turn to a prismatic joint (rail). I've read Roy Featherstone's Rigid Body Dynamics…
Chuck
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3 answers

What main factors/features explain the high price of most industrial computer vision hardware?

I am a student who is currently working on a computer science project that will require soon computer vision and more specifically stereoscopy (for close depth detection). I am now looking for a great camera to do the job and I found several…
Golitan11
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2 answers

Can I use ROS with a Roomba?

Is there anything different between a iRobot Roomba and the Create? I want go start building my own turtlebot and playing with ROS but with the cost of all the parts I'm going to have to do it piece by piece. It's pretty easy to find cheap used…
JDD
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7 answers

What is the difference between motion planning and trajectory generation?

What are the major differences between motion planning and trajectory generation in robotics? Can the terms be used interchangeably?
Ratan Sadanandan O M
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How to charge a LiFePO4 battery?

From what I've seen, LiFePO4 batteries seem like one of the top battery choices for robotics applications. However, I've seen people mentioning that you can't use a charger for a different battery to charge these, but I haven't seen why. If I were…
golmschenk
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What algorithm can I use for constructing a map of an explored area using a number of ultrasound sensors?

Ultrasound sensors are incredibly cheap these days which makes them a popular choice for many hobbyist robotic applications, and I'd like to use a bunch of them (say 10) around a robot with an algorithm to build a rough map of an area (as the robot…
berry120
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1 answer

How can I optimise control parameters for a stepper motor?

As an industrial roboticist I spent most of my time working with robots and machines which used brushless DC motors or linear motors, so I have lots of experience tuning PID parameters for those motors. Now I'm moving to doing hobby robotics using…
Mark Booth
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Forward Kinematics/D-H parameters for perpendicular joint axes

I am trying to compute forward kinematics of the Kuka youBot using DH convention: http://www.youbot-store.com/youbot-developers/software/simulation/kuka-youbot-kinematics-dynamics-and-3d-model The arm joint 1 and arm joint 5 are revolute and rotate…
aac
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