# Questions tagged [control]

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

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9answers
292k views

### What are good strategies for tuning PID loops?

Tuning controller gains can be difficult, what general strategies work well to get a stable system that converges to the right solution?
6answers
6k views

### Robot never goes straight

I am using 2 identical DC motors and a castor wheel. The motors are connected to L293D motor driver and are controlled by RPi. The robot is not going straight. It veers off to the right. I am ...
1answer
2k views

### The aerial refueling problem: sketch of a feedback controller

At first happy new 2015!!! I'm looking for my next simulator development: a Tanker is flying at constant speed (350 Knots) (no acceleration, no change of altitude or direction). The Tanker is ...
2answers
11k views

### How do I calculate the required loop frequency for a servo controller?

I have a motor which drives a string connected to a load cell. I would like to implement a closed loop controller to control the load applied by the motor to the string. How do I go about determining ...
3answers
4k views

### jacobian of Abb irb140 robot

Can someone please help me with the jacobian matrix equations for Abb irb140 robot. Or an easy way by which I can derive it given the DH parameters. I need it to implement some form of control that am ...
2answers
4k views

### How to calculate the right and left speed for a tank-like rover?

I am trying to control the Rover 5 robot using an Android app with a touch-based joystick control in the app UI. I want to calculate the speed of the left and right motors in the rover when joystick ...
2answers
6k views

### How to further understand the computed torque model controller

For the following controller what do $q_{des}$ and $q_{act}$ stand for? Also, what is the general principle of this controller? Thanks!
1answer
729 views

### Quadcopter PID Controller: Derivative on Measurement / Removing the Derivative Kick

Good day, I am currently implementing a single loop PID controller using angle setpoints as inputs. I was trying out a different approach for the D part of the PID controller. What bought this ...
3answers
5k views

### How is PIV control performed?

I'm considering experimenting with PIV control instead of PID control. Contrary to PID, PIV control has very little explanation on the internet and literature. There is almost a single source of ...
2answers
1k views

### Tracking objects from camera; PID controlling; Parrot AR Drone 2

I am working on a project where I should perform object tracking using the camera of Parrot AR Drone 2.0. So the main idea is, a drone should be able to identify a specified colour and then follow it ...
3answers
139 views

### Quadcopter PID Controller for distance

I am trying to use a PID controller to stop a quadcopter at a specific location while travelling horizontally, however currently it overshoots/undershoots depending on the max velocity. I have tried ...
1answer
3k views

### ROS: Best practices?

I'm going to build a small robot system, and it seems like that ROS serves a nice framework to control and program the system. However, I am wondering which is the best practice to manage the ...
3answers
19k views

### Position Control vs Velocity Control vs Torque Control

Please can somebody explain to me the difference between Position Control, Velocity Control, and Torque Control? Specifically, I am thinking in terms of a robot arm. I understand that position control ...
3answers
9k views

### I don't understand Integral part of PID controller

I dont understand integral part of PID controller. Let's assume this pseudocode from Wikipedia: ...
4answers
6k views

### how to implement tracking problem with PID controller

I'm trying to implement the tracking problem for this example using PID controller. The dynamic equation is $$I \ddot{\theta} + d \dot{\theta} + mgL \sin(\theta) = u$$ where $\theta$ : joint ...
1answer
5k views

### Quadcopter PID Algorithm

I'm trying to implement a PID control on my quadcopter using the Tiva C series microcontroller but I have trouble making the PID stabilize the system. While I was testing the PID, I noticed slow or ...
2answers
210 views

### Biped State Space Implementation

Currently I working on a humanoid robot using inverted pendulum model and use LQR for walking stabilizer. Input u is Torque, State x is angle and angular velocity and y output is angle. I got the ...
4answers
6k views

### How can I modify a low cost hobby servo to run 'freely'?

I've got some hobby servos (Power HD 1501MGs) and I'd like to be able to control them (via an Arduino) so they will either go to the angle I set, or put them in a 'free running' mode, where the load ...
3answers
675 views

### Using genetic algorithm for tuning controllers

I've read some papers for controlling nonlinear systems (e.g. nonlinear pendulum). There are several approaches for targeting nonlinear systems. The most common ones are feedback linearizaing, ...
5answers
539 views

### Arduino Motor control

I'm working on a rather low budget project, and need some way to control four or more motors using one Arduino. I've looked at motor shields a little, but I have a shield on top of it already, It does ...
2answers
5k views

### Quadcopter PID Control: Is it possible to stabilize a quadcopter considering only angle measurements?

Good day, I am a student currently working on an autonomous quadcopter project, specifically the stabilization part as of now. I am using a tuned propeller system and I also already considered the ...
4answers
4k views

### What are the advantages of optimal control as opposed to control theory?

For a robot, say path planning in particular, what are the pros and cons of choosing classical control theory or optimal control (LQR for example) ?
3answers
585 views

### Proportional controller error doesn't approach zero

I'm reading this pdf. The dynamic equation of one arm is provided which is $$l \ddot{\theta} + d \dot{\theta} + mgL sin(\theta) = \tau$$ where $\theta$ : joint variable. $\tau$ : joint torque ...
3answers
1k views

### Control VS artificial intelligence?

I have heard of both the terms AI (artificial intelligence) based robots and control based robots. Although they are both different fields, what is the difference between AI and control in regards to ...
2answers
509 views

### Two-wheeled self-balancing robot - Choosing the control system

Would an Arduino Uno have the precision-timing required (using only firmware) to control a two-wheeled inverted pendulum robot, or would it need a RTOS? Note: Thanks for both answers, they both ...
2answers
2k views

### Self balancing robot control system strategies [closed]

I’m in the early stages of designing a self-balancing robot as a way to refresh my knowledge on control theory, which has been gradually slipping away since graduating about a year and a half ago. I'm ...
2answers
284 views

### What is the right approach to write the spin controller for a soccer robot?

Imagine programming a 3 wheel soccer robot. What type of controller would you use for spinning it? P? PID? The goal for this controller is that it should make the robot stand in a defined angle ( 0 ...
3answers
907 views

### How can I control a fast (200Hz) realtime system with a slow (30Hz) system?

We are currently designing a mobile robot + mounted arm with multiple controlled degrees of freedom and sensors. I am considering an architecture in two parts: A set of realtime controllers (either ...
1answer
498 views

### Is the geometric inverse problem's solution “continuous” for a redundant robot?

Let's say my redundant robot is at an operationnal position $x$. Is the set of all possible joint configuration "continuous", which would mean that it is possible to explore all the possible ...
2answers
403 views

### Good method for Retuning a PID After Detecting Oscillation

Given a PID controller with an anti-windup, what are some practical ways to retune the controller once oscillation has been caused and detected? I have access to the magnitude and period of the ...
1answer
249 views

### PID control: zero out integral on error sign change?

I am learning about PID as a novice to robotics (background in software engineering). One common problem with PID is that if the PV is below the SP for a long time, integral term will accumulate a ...
1answer
61 views

### Issue with series command in MATLAB

I have a controller and a plant in series. The controller is 3 input 3 output MIMO system and the plant is also 3 input 3 output system. The bode of the open loop gain, i.e., $$D(z)=C(z)*G(z)$$ ...
1answer
639 views

### Quadcopter PID output and duty cycle conversion

I'm trying to design two PD controllers to control the roll and pitch angle of my quadcopter and a P controller to control the yaw rate. I give to the system the reference roll, pitch and yaw rate ...
1answer
435 views

### Linear Motion Control for quadrotor (clarification)

I've posted a question regarding this matter that I couldn't solve. I'm reading this paper, the authors state Linear $x$ and $y$ Motion Control: From the mathematical model one can see that the ...
1answer
173 views

### How do I convert centre-returning joystick values to dual hobby-motor direction?

Currently my setup is: 2x hobby TT motors connected to a Pi Zero with a motor HAT Python script running on the Pi which runs a Blynk python client and controls motors via the gpiozero library Blynk ...
1answer
837 views

### PID Controller Output Mapping for Motor Speed Control

Hi, I want to control the speed of a conveyor belt. I can measure the linear velocity of the belt using a encoder mounted at the roller of the belt. My confusion is not with the PID but only the ...
3answers
827 views

### PD Algorithm for a Quadrotor [Simulation]

I have a big problem trying to stabilize a quadrotor with a PD controller. The model and the program has been written in C++ and the model dynamic has been taken from this source in internet: Well, ...
2answers
395 views

### Math behind trajectory planning

Let's assume the very simple case of a particle and a control system in one dimensional space therefore our particle can move only in a straight line and dynamics of system is described by: \$m\vec{a} ...
2answers
332 views

### Motion planning and robot controlling

I am stuck with understanding how can I make my robot move along planned path. For instance, if we have a grid map of an environment and applied, for example, A* to plan a path then after that we have ...
0answers
27 views

### Multidimensional obstacle avoidance in ODE. Part II

Multidimensional obstacle avoidance https://math.stackexchange.com/questions/4146255/multidimensional-obstacle-avoidance-in-ode For some time, I studied this question more closely and came to the ...
0answers
220 views

### Quadcopter force/torques duty cycle conversion

after having been determined my control loops for my quadcopter project, I'm going to determine the motor commands (PWM duty cycle) from the motor forces/torques. I was following the guidelines of ...
1answer
101 views

### How do i use the Nicolas ziegel approach if my system never becomes unstable?

How do i use the Nicolas Ziegel approach when the root locus plot of my system never becomes marginally stable , for any gain (unless it is negative).. ?? How do i estimate my ultimate gain value????
1answer
495 views

### Why can't the Controller Spawner find the expected controller_manager ROS interface?

I have a quadruped robot with base link (BL), 4 child links called LFT, LFT, RFT, RFT, T for thigh and each having 4 children with name LFC, LBC, RFC, RBC, C for Calf. 8 joints - Base link to 4 thighs ...
1answer
53 views

### Multidimensional obstacle avoidance

Artificial potential barriers are known that allow robots to avoid obstacles. They are constructed as follows. https://authors.library.caltech.edu/106548/1/2010.09819.pdf Can you please tell me how ...
2answers
53 views

### High derivative gain in PD control

Why does high derivative gain in PD control results in motor noise or chatter? The graph that I see on MATLAB simulation is smooth enough, so following that it should not make noise..
2answers
176 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 ...