Questions tagged [control]

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

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2answers
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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
49 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
1k 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
59 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
47 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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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
141 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
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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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178 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
927 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
119 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
562 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
330 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
207 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
342 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
49 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
53 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
248 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
71 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
435 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
82 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
208 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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1answer
26 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 ...
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2answers
2k views

Alternatives to Finite State Machines (FSM's)?

In Udacity's Self-Driving Car Engineer online course, one instructor claims that "[Finite State Machines are] not necessarily the most common [approach for behavior planning] anymore, for reasons we ...
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1answer
410 views

Pictures coordinates to robot coordinates

I have a picture on my C# software and the corresponding object in real world on 2d plane of motorized XY axis table. What I want is when I select a pixel on my picture, the motorized table should be ...
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2answers
584 views

Pole placement of the observer closed loop system (A-LC) in discrete system

*I'm rewriting the question after I deleted the previous one because I wasn't clear enough. Hope it's fair Given a system of the general form: \begin{align} x_{[k+1]} &= A\,x_{[k]} + B\,u_{[k]} \...
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2answers
123 views

Dynamic model using identification for control

I'm currently working of a 5 DOF robot, for which i'd like to compute the dynamic model through identification. I have experimental data representing torques (inputs) and positions (outputs). How can ...
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1answer
244 views

zero-g mode for UR10 gravity compensation

I would like to freely move my UR10 arm in response to an external force, just like the zero-g mode for Baxter robot, which can be activated by holding its wrist. The Baxter documentation on zero-g ...
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1answer
61 views

Obstacle Avoidance: Detection of goal inside the obstacle

It is easy to understand how a robot can avoid obstacle if the goal point is not within the obstacle (Point A) as shown in the figure. But I'm curious how could a robot know that the the goal point is ...
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1answer
54 views

Inter-robot Collision Avoidance

I try to understand some MATLAB code (see below) i found from the web for inter-robot collision avoidance. But I'm not really understand, how the theory behind this code work. Can anyone help me ...
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2answers
311 views

Quadcopter mathematical model and controller design

if we just examine the translational dynamics (X and Y direction), the dynamics are coupled, So if I want to design a PID controller to control the position, the outcome will be unpredictable because ...
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0answers
58 views

Quadcopter bldc PID control

Working on stabilizing a Quad using Arduino Due. I have slightly modified one of the examples of Jeff Rowberg's library to give yaw, pitch and roll angles (zero initialized angles). Moreover, I am ...
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1answer
345 views

State space model

I want to design a LQR controller for my two wheeled mobile robot. While designing the controller, I need to find gain, K for the LQR which this required the state space model of wheeled mobile robot. ...
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1answer
73 views

Torque commands for velocity reference motor

I have a controller board for a motor, where I can read the motor current (to transform to torque), the position, the velocity and I can give a velocity command. There is not really a torque mode on ...
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2answers
134 views

Controlling a servocity planetary motor?

I know this might sound like a stupid question, but I actually need help with this. So, I'm looking at this motor: https://www.servocity.com/2737-rpm-premium-planetary-gear-motor. I have a raspberry ...
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2answers
74 views

How to start as a control system engineer and to make advanced projects using PID [closed]

I am new to the field of control systems, PID and robotics and I want to enhance my knowledge in the field. Can you recommend me books where I can start learning about control system engineering (with ...
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3answers
123 views

Making a tunnel follower robot with 2 IR side sensors and 1 ultrasonic sensor

We have a tunnel and the distance from the walls to the robot is about 30cm when the robot is centered, the tunnel curves to the right. The robot has an infrared sensor on its left and one on its ...
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1answer
55 views

Strange phase case in Bode diagram of a transfer function [closed]

Please help me to solve my problem: This is the transfer function: $G(s)=10\frac{(s^2+1)(s-10)}{s(s+0.1)(s^2+2s+100)}$ I calculated properly the whole Bode diagram apart from the phase of the complex ...
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2answers
55 views

Powering Off Main Processor Without Software shutdown

I am building a robot that uses an Intel NUC (running ArchLinux) as its main processing unit to run some machine learning and ROS programs scripts. One of the requirements for the robot is that it ...
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1answer
61 views

Control geared DC motor based on timing?

According to this video from Khan Academy about electronics of a DVD drive the position of the sled (which moves the reading head) is controlled by a geared DC motor by using only timing and one end-...
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1answer
489 views

Quadrotor 2D Dynamics

I am trying to understand the control of the quadrotor in 2 dimensions from the Penn course on aerial robotics. The attached image describes the linearization of the control efforts assuming that the ...
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2answers
168 views

How to implement reference control signal for robot heading?

Some time I found that some robot controller uses a critically damped reference control signal such as in Autonomous Surface Vehicle (ASV) heading controller. My question is how do we implement this ...
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1answer
329 views

Quadcopter filter and Angular rate vs angle (Arduino programming)

I wrote an Arduino program for my quadcopter that sets to power of the 4 ESC's using software. Now I need to incorporate the gyro and add a "Complementary Filter" to stabilize it. I am currently ...
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1answer
85 views

Is Robust Control and robotics well applied together?

There are many control methods who sounds great and have nice math etc. But many of them are not realistic in real life. In robotics, Adaptive Control is well applied because Adaptive Control make ...
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1answer
618 views

Are S-Curve (constant jerk) motion profiles significantly better than constant acceleration?

I've been investigating S-Curve motion profiles for CNC router and 3D printer applications, and haven't come across any definitive source that says an S-Curve profile is necessary in any application. ...
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2answers
72 views

How many stages necessary to stabilize position while controlling torque?

I'm assuming that since torque translates into acceleration, the basic transfer function from torque to position becomes $1/s ^ 3$ Does this mean that 3 pid controllers are required to properly ...
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1answer
58 views

How can I run Tests/Simulations of Control and Motion Planning for a Bare Metal Robot?

I am using a raspberry pi to practice low level development with a differential drive robot; bare metal without an OS underneath. I've gotten to the point where I have a very small, single purpose ...
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0answers
166 views

My robot arm vibrates during operation. Why?

Introduction: I have modeled my 5-DOF robot arm in a simulation environment to test trajectories for my physical model. I have export the joint variables from the simulation as a .csv file. Then ...
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1answer
91 views

Quadrotor SE3 Controller: Calculating Rd_dot

I am trying to simulate and implement the controller in the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). I have the dynamics implemented, however I am stuck at one part in the ...
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2answers
739 views

Quadrotor Dynamics: Calculating angular velocity of quadrotor

I am trying to simulate and implement the controller of the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). To do this I need to first implement the dynamics of the quadrotor. According ...

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