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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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1answer
18 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
32 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
25 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
31 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
46 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
89 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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0answers
21 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
70 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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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 ...
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2answers
103 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
22 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
26 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
24 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
39 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
110 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
19 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
29 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
67 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
91 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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0answers
63 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
35 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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0answers
7 views

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
21 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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0answers
20 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
76 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
80 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
50 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
25 views

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 ...
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0answers
31 views

Why differential flatness is called “flat”?

A system is differentially flat if the state and control input can be written as functions of the flat outputs and their time derivatives. In other words, if a system is differentially flat, we can ...
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5answers
116 views

Why we want to write all linear system into form of first order differential equations?

It seems to be taken granted that when we deal with some control system, the first thing we want to do is to linearize the system and put it in form of first order differential equations like $\dot x =...
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3answers
139 views

PID and Kalman filters

Both PID and Kalman filters are used extensively in Robotics. I gather, Kalman filters for sensing and PID for control. What is the mathematical, statistical or other relationship between them?
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2answers
90 views

How to implement a novel control algorithm for a drone

I and my research team are working on a novel drone design based on trirotor. The difference between this design and a trirotor is that it has an extra propeller to generate additional thrust, ...
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3answers
68 views

How many independent control inputs does a hexarotor have?

6, because a rigid body has six degrees of freedom 4, since it is similar to a quadrotor, except with more motors 6, because there are six motors I was taking an online quiz, and I thought option 3 ...
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1answer
44 views

PID control related to lagrange equation

I'm a beginner in robotics and so far followed the lecture series by Prof. Oussama Khatib and some blogs and papers. currently I'm following this studywolf blog. in the end I plan on building a simple ...
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2answers
108 views

Problem with tuning PID for motor

I am trying to tune my PID to make my motor have a consistent output: input(pidOutput) => 100rpm I used the following step to tune my PID: Set all gains to zero. Increase the P gain until ...
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2answers
57 views

Meaning of a negative step response with quaternion

It's not technically robotics but: I've been trying to reproduce in Simulink a spacecraft attitude simulation using quaternions, and the kinematics and dynamics seem to work fine, however I'm having ...
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1answer
73 views

stable altitude quadcopter

I'm currently working on a project to generate a stable altitude and automatic control for a quadcopter I'm using arduino as the flight controller Ultrasonic sensor HC-SR04 MPU-6050 However my ...
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1answer
85 views

Quad-rotor 1-D Linear Control Simulation with MATLAB

I was Performing Programming Assignment with MATLAB for Quad Thrust and Height for an Introductory Course. The control input for a PD controller was According to the Equation u = mass*(diff(s_des, 2)...
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1answer
27 views

How can I limit the current sent to my 6V servos to ensure they don't burn out?

I'm using an adjustable desktop power supply (0-30 volt DC, 0-10 amp) to power my robot which has 7 standard 6-volt servos. There are some situations where the robot gets jammed, and power draw ...
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1answer
45 views

Could a quadrocopter still be controllable if its payload was wider than the quadrocopter?

Lets say a quadrocopter's rotors are 2 feet apart, and 2 feet beneath it is attached a symmetrical, balanced payload that was x feet wide (with space for air from the rotors to move through) - if the ...
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1answer
51 views

Creating linear end effector motion using joint speeds: Converting tool speed to joint speeds

Background Information: I'm new to robotics and my school currently has access to a 6DOF Universal Robot (UR-10). I'm programming it using its scripting language URscript and the arm has these two ...
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0answers
26 views

Trajectory following using LQR - Setting horizon time and intermediate points

I was going through UC Berkeley's CS287 - Advanced Robotics course. In particular - Optimal Control for Linear Dynamical Systems and Quadratic Cost (“LQR”) by Pieter Abbeel (Slide 10). Let us say we ...
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1answer
113 views

Control Pneumatic Cylinder Position with Potentiometer and Analog Comparator on Arduino Uno

I am building a robot arm that is actuated by a pneumatic cylinder. Extending and retracting the piston would increase and decrease the joint angle respectively. This is done using a 5/3 solenoid ...
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1answer
57 views

Math behind trajectory 2d planning

I have a case of a differential drive robot and a control system in a two-dimensional environment: Now the problem: we would like to make our particle move from point A to point B, and from there to ...
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1answer
83 views

Is orocos dead?

We are using orocos on the robot we have been developing for 3 years now and I have the feeling that Orocos is no longer maintained and the mailing lists are not only no longer active but also it is ...
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0answers
28 views

Sensored BLDC motor (sometimes) needs push to get started

I'm having a sensored BLDC motor (12V version though) connected to a suitable motor controller and powered through a 25A regulated power supply With an Arduino I'm able to control the motor just fine. ...
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1answer
23 views

Motorised Stage for laser

The problem I want to be able to move the direction a laser is pointing. This means I need to have motorised rotation of the laser head in the x direction and in the y direction. I am unsure of the ...