Questions tagged [control]

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

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DC motors are stalling at low voltage (L298N controller)

I'm building a small tracked robot. Currently it's just a Raspberry Pi, two motors and an L298N controller. The problem I'm facing is that the motors are stalling at low voltages (which is what I ...
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Self motion with multiple constraints

I am trying to control a 7 DOF robot (a Franka Panda). I use jacobian based control (resolved rate motion control) to generate a joint trajectory from a cartesian trajectory. My contraints for the ...
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Using Integral gain for motor positioning

I'm struggling to see how Integral gain is used for motor positioning (with an encoder on the shaft). Suppose we have an AC motor connected to a winch which drives an object forwards and backwards. ...
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Use polynomials to detach number of MPC controls from size of time-horizon?

Model Predictive Control (MPC) works by finding a set of controls $u_0, \dots, u_n$ that minimize a cost function $J$ over a time-horizon $[t, t + T]$. Typically when MPC is used on mobile robots, ...
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What servo and controller to use on a o scale model to make a rocking chair move up and down [closed]

I’m trying to design a rocking chair to move back and forth on a O scale diorama and I would like to know what type of servo and controller to buy to achieve this
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Numeric integration problem in a quadrotor vertical descend code

I'm trying to implement a drone in vertical descend. As for maximum simplification, I maintain all its angles to 0, and just try to get to the my desired descend. However, when I debug, I see that my ...
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Link collision avoidance for redundant manipulator

I am trying to have my robot arm follow a trajectory while avoiding collisions between obstacles and the robot links. The way I go about it is to find the closest point on the robot arm, and treat the ...
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FPGA vs Neurochips for Control Systems [closed]

Greetings to all respected colleagues! I want to consult on the use of FPGAs and neurochips. I plan to use it in my laboratory project for programming control systems on neural networks. Please share ...
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Good Software Projects for Aspiring Engineers [closed]

With the pandemic going on, our school has decided to officially shutdown all sponsored club meetings. Now that we are all digital, our robotics club was looking for projects that students can do at ...
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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 ...
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How do “process gain” and “proportional gain” affect the Steady State Error in a PID Controlled machine?

I came across this doubt while reading the Wikipedia page on PID Control. The section on Steady-state error states: Steady-state error (SSE) is proportional to the process gain and inversely ...
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discrete control in continuous spaces

I asked this question on AI stack exchange but didn't get a response. Basically I'm interested in how you deal with inherent error between your ideal discrete state and your actual state in control ...
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How to design a controller for a robotic arm given two velocity profiles

See image for reference: Essentially I have a robotic arm with two linear actuators. Lets say, for example, I wanted the endpoint on the arm (where you see the stepper motors) to move purely in the x ...
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PD controller tuning for flexible joint robotic arm

I am trying to tune the gains of my PD controller for a single axis flexible joint robot. The controller output is the motor torque. My question is: how can i tune the PD gains if the output (torque) ...
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What should be the ideal ratio for link lengths ( L1/ L2) of a 2 link manipuator robot with revolute joints?

I am working on making a CAD model of a two link robotic manipulator, with link lengths around 15-20 cm. I am unable to figure how to set their mutual ratio and I want to know whether there is some ...
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Why applied joint torque will affect another joint?

I want to ask a very simple question. For the robot dynamics Newton-Euler algorithm, suppose there is a two-link planar robot, we can write the simple dynamic equation form as $M(\theta)\ddot{\theta} ...
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Understanding Impedance Control

I have a question regarding impedance control for a robotic manipulator. Given that we have a task space trajectory: $\ddot{x}$, $\dot{x}$ and $x$ And the dynamics model of the robot: $$\tau = M(q)\...
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Increase frequency of status messages from UR5

I know the UR5 is sending me messages with its status (I can't yet understand them though, but I'm already working on that). However, they are too far apart to be useful: It sends them every 0.1 s. ...
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Interpret 560 byte msg from UR5 firmware 1.8 through TCP socket

I am trying to use the UR5 from my computer without having to write any script on the robot. For that, I opened a TCP socket as a client from my computer (in a C program), and the robot indeed does ...
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1answer
64 views

Controlling a robot arm to follow an SE(3) trajectory

I have a 7-DOF robot arm, and I want it to follow a trajectory. This trajectory is defined as a dense sequence of SE(3) waypoints, which were collected by moving the robot arm manually (i.e. by ...
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Algorithms for controlling low-speed movement of gearless robots

Collegues, i am a little discouraged by the lack of a clearly formed section in the literature on which algorithms are used to control the low-speed movement of gearless robots. In my opinion, it is ...
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Constructing control system

The problem i have is more or less is biology related, but I can simplify the problem as such. I have a tank of water. I try to increase the concentration level of this tank of a certain substance (X) ...
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Going from Spline to Differential Drive Command

I have a differential drive robot that needs to move along a path stored in its memory as a spline. I am currently trying to understand the mathematics of determining how much power to apply to each ...
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(not trivial) ROS how to subscribe to multiple topics and publish to another topic within one loop

My question is related to this one (here) but not exactly. Assume now I have 4 topics: topic_A,topic_B,topic_C,topic_D. Inside my control loop, I need to read the sensor values from the first three ...
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implement torque control on a robot with some joints supporting torque control while others only supporting velocity control [closed]

I have a robot, some joints of which supports torque control,while the rest only supports velocity control. What should I do to implement torque control on the whole system?
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Why are the angular velocities of concentrated masses in Lagrangian independent?

There is an ordinary linear three-mass system. If we write its Lagrangian, we get the following equation. where $W_k$ and $W_n$ - kinetic and potential energy. To find the moment of rotation of the ...
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Robot-telescope prototype controlled by a PC

Has anyone developed mechatronic systems for DIY-telescopes running a PC? Please share your experience, knowledge and nuances (how you acquired current sensors, speeds, electric motors, about ...
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2answers
58 views

Dynamic models of parallel robots in the form of multi-mass systems with stiffness coefficients

I want to develop a dynamic model of a parallel robot for control tasks. It is known that equations of motion based on Lagrange equations can be transformed into a state space and use such a model. ...
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Modeling of Robots

There are mainly two approaches for controlling robots (mobile robots and static robots): 1) working with kinematic equations, controlling joint or wheel speeds , 2) working with dynamic equations and ...
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Extract Coriolis matrix from Coriolis*q-dot vector multiplication

I have been using matlab to do some robotics simulation. I am able to Create the forward kinematics with transformation matrices Create the jacobian matrix Find joint velocities Create the ...
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MAV drifting away from its takeoff position

I am working on MAV control in GPS denied environment using px4flow and Lidar sensor.While in simulation and during experiments on real vehicle, MAV doesnt stay at its position and drifts in random ...
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About the commonly used equation of distributed consensus of multi-vehicle systems, is this form correct?

$\dot \epsilon = -(L_{n}\otimes I_{m})*\epsilon$ This equation is commonly cited in works about the distributed consensus of cooperative control. In fact, it's the matrix form of the basic consensus ...
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How to avoid singularity in ABB robots while using it with EGM (externally guided motion)

I am using the IRB120 robot and controlling it with Azure Kinect body tracking data. I am using EGM as an interface to pass the data from kinect to the ABB robot. But here sometimes the robot stops ...
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3answers
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Implementation of Velocity Control Algorithm Based on PID

I'm very familiar with the traditional position form of PID. The error is just the difference between some setpoint encoder value and the current encoder value. Although this suffices for basic ...
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Motion Planning vs. Control

Often I see positions for robotics companies split into planning and controls engineers. But motion planning and controls seem to have a lot of overlap. As I understand in motion planning the ...
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Multithreading on robot control

Is it wise / possible to use multithreading to handle control system on robot? For example, a line follower robot with PID control flowchart would be: read_sensor() -> calculate_control() -> ...
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Why am I unable to tune the PID parameters on my quadcopter?

I am building a nano quadcopter in X-Configuration with coreless DC motors, 65mm 2 blade propellers and a 1S Lipo battery (860mAh, 25C). The weight of the assembly is around 70g in total. I am ...
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1answer
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Control loop in or outside of main loop

I've been working on some small projects for fun to learn more control theory things and embedded programming. Thank the esp32 and Arduino! Either way I've been programming everything entirely in a ...
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Is it possible to make a self balancing robot using small or medium scale integrated circuits?

Almost all the information I've seen about self-balancing robots implies the use of an Arduino to implement the control. I'm wondering if it is possible to implement the control using just small or ...
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Inverted pendulum controller

I had an exam yesterday, and I was asked the following question: Why PID controller is necessary for stabilizing the inverted pendulum on a cart, why not we just use PI or PD? Now I've seen some ...
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What is the Control mixer block that is usually found in control schemes?

There is usually a control mixer block in control schemes in robotics. What is it and what is the functionality and where can I read more about it. Reference to the paper: https://giuseppesilano.net/...
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Compensator design

I got a plant $G(s)=\left(0.13s+1\right)/s^2$ to design a compensator which provides below demands: Settling time : max 2s Overshoot : max %35 Gain margin : min 10 dB Phase margin : min 30 deg ...
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How does TTS TacTile Code Reader work?

This is the TTS TacTile Code Reader: https://www.tts-international.com/tactile-code-reader/1010494.html?cgid=Primary-Computing_--_ICT-Bee-Bot_Blue-Bot_--_Pro-Bot There aren't any connection pins, I ...
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feedback linearization for a quadrotor

I am trying to develop a controller for a quadrotor using dynamic feedback linearization technique, but I am not sure I am doing thigs correctly. I know that for designing such controller I have to ...
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3answers
193 views

How to control the velocity of a mobile robot?

I have a differential drive robot whose linear velocity and angular velocity is to be controlled. The current strategy for doing that is: A high level path tracking module spits out the reference ...
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Partial CoM, the velocity Jacobian and Control

New to robotic arms here. I am currently working with a 6-DOF robotic arm shown below: I have derived the FWD Kinematics and mapped the joint angles and the resulting end-effector positions. When I ...
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value of $\gamma$ in the H-infinity norm

Suppose I have the system: $\dot{x} = Ax+Bu$ $y=Cx+Du$ and the following Hamiltonian matrix: $H=\begin{pmatrix} A & \frac{1}{2}B^TB\\ -CC^T&-A \end{pmatrix}$ I want to find the value ...
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Finding transfer function from bode plot

I try to estimate a system transfer function by hand calculation from a bode plot data but I could not succeed yet and I need someone help. it will be appreciated if anyone explains or refer me to a ...
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2answers
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Block algebra and normal algebra inconsistent

I've been playing around with some block maths, mostly trying to remember how it actually works, and I've come to a simple example that should be reduced, however when doing the normal maths, compared ...
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Why would I use three state variables for a second order system? [state space modeling]

I'm currently being asked to write a state space model of a falling object (equation attached). I had taken a linear systems course five years ago in which I did a lot of conversion between high ...

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