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Questions tagged [control]

A method or device to manage, command or regulate some part of a system.

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Robot control project [on hold]

So currently I have an unused robot car, my plan here is to be able to control the robot car with a joystick using ros_control. I am really new to ROS and is hoping you guys can guide me along. I ...
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19 views

Why do I need impedance control?

I am having a hard time understanding the impedance controller. I see that it looks at the manipulator as impedance and the environment as admittance. However, it is hard to grasp the concept and ...
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16 views

Falcon Heavy Control Algorithms

What kind of control approaches does SpaceX use for landing of their Falcon Heavy boosters? Is it PID, LQR or something more advanced?
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1answer
24 views

Design a robot that can apply hot glue to paper

I need to automate a process that involves applying hot glue to paper. I own a standard handheld hot glue gun, like this one: Sticks of room-temperature glue are fed in the right side. Pulling the ...
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1answer
66 views

Why is the Kalman filter a filter and not a control system?

Why is the Kalman filter a filter and not a control system? The Kalman filter is a recursive filter which can be used to estimate the internal state of a linear dynamic system with noise in the signal(...
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increase of sensitivity bandwidth with H-infinity optimization

I have defined a defined a controller using the H-infinity optimization in Matlab using just the sensitivity weigth in the following way: ...
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33 views

Real-time python reinforcement learning library

I'm looking for a reinforcement learning library that can be used for real-time robot control. What I first had in mind was ROS to describe the robot, Mujoco to simulate physics, and OpenAI gym to ...
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11 views

Control Algorithms for Kinesthetic Teaching

There are several algorithms for post-processing of kinesthetically demonstrated motions for manipulators learning a task. However, I have failed to find papers/research work on modeling the ...
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22 views

How to add some more feature for this simulink model

After some research Robotic hand simulation in MatLab? After some motivation, I have tried to go inside Matlab Simulink and was able to do this :- https://drive.google.com/open?id=...
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1answer
25 views

Image based visual servoing for quadrotor forward flight

I'm still trying to understand how to implement image based visual servoing (IBVS) for quadrotor. The control laws seem straightforward if you want to use IBVS to track a feature in the image space at ...
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26 views

How to find Q and R in the Kalman filter according to known noise information?

My team built this linearized model in Simulink which works pretty well. I am currently building a continuous kalman filter. I assume some noise disturbance in the input and the measurement like what ...
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22 views

TGY-6114MD Servo motor needs push to start

I currently have an inspection robot deployed in a remote part of Africa that has a failing Turnigy TGY-6114MD servo. The issue appeared randomly. The servo won't respond to commands unless given a ...
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1answer
55 views

Is there a more accurate feedback loop with less overshoot or disturbances than PID?

So I was starting a robotics project and turns out that PID hasn't served very well in the past. So I was wondering if there was another feedback loop mechanism which has less overshoot and is more ...
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1answer
40 views

Add control and planning trajectory to double pendulum [closed]

How do I control a double pendulum to get the end effector link to go in the trajectory shaped in a perfect circle? I have the equation of the circle to go in but I don't know how to get the double ...
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Rigid body system identification with machine learning, but how?

Most problems in robotics have to do with a controlling a system. An easy example for a system is the forward kinematic of a robot arm. A joint in the model gets a certain value, and as the result the ...
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2answers
58 views

Robotic hand simulation in MatLab?

We are doing graduation project and require simulation of the robotic hand to be submitted. And we want to control various parameter in for movement for fingers of robotic hand. We tried it in other ...
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1answer
99 views

How to limit large acceleration and jerk from PID controller?

I am trying to control a robotic arm with force input. The output of the force sensor is filtered, and fed through a PID controller to command the end-effector velocity. However, the robotic arm has ...
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23 views

Overcoming or managing deadband in vehicle steering controller [duplicate]

I found out there is a deadband in my steering controller after several runs. And the transfer function for it in the \$s\$-domain is $$ H(s)=\frac{270\cdot e^{-0.03s}}{0.015\cdot s + 1} $$ To ...
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1answer
37 views

Are examples for jerking robotarms available?

I'm trying to find some youtube videos which are showing robot arms with some malfunction in it. The problem is, that the keyword is unclear. Should i search for “unstable”, “tremble”, “jerking” or “...
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1answer
38 views

motor controlled lazy susan

I'm trying to figure out an easy lazy susan setup. This is for video production, I want to be able to put an object on the platter and get a smooth consistent turn in order to shoot the object ...
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1answer
48 views

What is a Velocity Smoother?

I'm learning ROS and I have found an expression that I don't understand. I'm reading the book "Mastering ROS for Robotics Programming - Second Edition", and on a controller to move a robot using ...
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1answer
37 views

Is system identification and a physics engine the same?

In the control theory the term “system identification” is used quite often. A typical sentence in a robotics oriented paper is that the author is trying to “build a model of a plant with matlab”. The ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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2answers
109 views

How to approach any advanced control problem in robotics

I have worked on a couple of projects like control of a quadrotor/ self balancing robot/ 6 dof robotic arm using nonlinear, optimal and adaptive control. So, in all these projects I have first ...
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1answer
26 views

Controlling YuMi robot by serial port

I'm trying to control the YuMi robot arm by a serial port. The serial port will give the information on what direction the end-effector should move and what is the velocity. What I would like to ...
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2answers
32 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 ...
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2answers
27 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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1answer
40 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)]
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2answers
145 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 ...
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0answers
20 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 ...
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1answer
34 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 ...
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2answers
74 views

Why do we need to design controllers (feedback) for controlling a quadrotor?

For example if I want to make my quadrotor hover at a particular height, can't this be achieved by using an altitude sensor, and to correct it's position due to disturbances, can't we just write some ...
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1answer
115 views

Control system in Matlab with RSA encryption

I want to implement an encrypted controller in Matlab using RSA. I am trying to replicate what is written in this scheme from 'Cyber-Security Enhancement of Networked Control Systems Using Homomorphic ...
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77 views

Incremental (on-the-fly) smooth trajectory interpolation algorithm from waypoints?

short version (TL;DR): I'm receiving x(t) waypoints "online", which I must travel through at the specified times. I need an algorithm that would plan a smooth trajectory in-between them without ...
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1answer
47 views

How to calculate effort/torque values of a joint

I have a robotic arm with 6 DOF. For each joint, I get get the Joint Wrench, which is composed by the force and torque of the parent and child links of the joints. In other works, for joint 1 I can ...
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How to interpret the passivity criteria equation?

In Passivity-Based Control and Estimation in Networked Robotics (among others), a passive system is defined as one that: $$\int_0^t y^T(t)u(t) dt \geq -\beta $$ for output $y$ and input $u$. I have ...
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1answer
22 views

Will a change of motor driver improve motor performance?

I have this motor, from datasheet it works on the 6-12V range and has a no load current of 0.52A, and a stall current of 20A. I want to test the motor before buying an expensive motor driver. I have ...
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1answer
39 views

project to create a lighter wall [duplicate]

We are working in a project to help blind people cross the street alone .so ,Can I create a Virtual reality wall or a holographic 3d one that is visible in the Street and in all day times ?? ( morning ...
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26 views

Why are strain-wave/harmonic gears used in robots?

Also, what is the difference between the above gear drive vs other gear drives?
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2answers
117 views

Inconsistent results between Simulink derivative model and tf for PD controller

I'm designing a PD controller so that the response due to unit step should exhibit an overshoot of 20% and steady-state error less 0.01. I've computed the parameters Kp and Kd and double-checked the ...
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1answer
37 views

Robotic Arm Senior Capstone. Electronics/Controls/Sensors Questions

I am a mechanical engineering student currently working on my senior capstone. My team of all MechEs has to build a robotic "arm" where the arm is really just a link/bar of aluminum. The thing we ...
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2answers
89 views

Multivariable PID controller

I'm making a robot that uses two DC motors to move, and has two distance sensors on its right side. I want to make a PID controller to control the angle of the robot (using a wall as reference) and ...
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3answers
54 views

Benfit of behaviors & benefit of hybrid systems

I have two questions that I think are closely related: Why is it useful to introduce behaviors, e.g., goal-to-goal + obstacle avoidance? (The alternative would have been to just use a single behavior ...
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1answer
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What limits the observer eigenvalues size?

IIUC, the recommendation here of increasing the absolute size of the real part of observer eigenvalues is based on two factors: We want the observer to be updated as fast as possible (I suppose up to ...