Questions tagged [control]

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

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What is the proof for the control law for regulation control of a unicycle?

I am studying the probem of regulation for a unicycle. While studying, I have seen that in order to converge to the origin both in position and in orientation, we need to pass in polar coordinates, ...
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I'm looking for a simplified control scheme for a game-rendered robotic arm

I'm a programmer, but not savvy with robotics (to lay a baseline for my lack of knowledge). I have a game-simulated arm that allows me to set joint angles which it will automatically move the joints ...
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Best references for navigations function applied in obstacle-avoidance and collision-avoidance robotic applications

I'm looking for good recommendations about the topic of obstacle-avoidance and collision-avoidance for robotic application. If someone has a good academic overview of the topic can recommend me some ...
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No electric motors can handle being stalled for even short periods of time, even at low power. Is this statement true in all cases?

We were using a regular POLOLU d.c motor whose stall current is 0.36A. We want to use this motor in a robotic hand where the motor will be stalled while holding the object. We are limiting the current ...
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Error in Pose(): All values are zero for turtlesim/Pose

Here is the program I have written. The function is to make the turtlesim complete one revolution, with a fixed angular velocity and speed. ...
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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 ...
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Res-Scaling method beats PID controller. How?

Scenario: I have a robotic arm that has a (1D) lidar on its end, to orient itself with respect to the slant table in front of it. The lidar returns pretty accurate distance values in mm. The motor ...
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Understanding across gravity compensation, demonstration (Kinesthetic Teaching vs. Teleoperation) and inverse dynamics

I first state my humble probably wrong opinion on the connection of these concepts: In gravity compensation mode, each joint has equilibrium as its set point, a human demonstrator can effortlessly ...
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How do I call Matlab code into Simulink for doing a simulation for doing plots?

I have built a simulink model for performing cartesian regulation on a unicycle: and plot the results with a Matlab code but, I am not very confident with Simulink and so I don't know how to call ...
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Imaginary part in result of inverse laplace transform

I am working with a system(closed-loop feedback control) that has a transfer function like this F = 20*(s+5)/(s^4+13.5s^3+41s^2+80*s+100) this one is in the s-domain but for the response analysis, I ...
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Rotary Stage (high resolution controller for BLDC motor)

I am building a 3phase BLDC motor controller based on an STM32 MCU, a high resolution 26 bit optical encoder and a DRV8301 motor driver from TI. This is a for a high precision rotary stage for an ...
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Synthesis gradient observer

I ask the advice of specialists on control systems. We have the following system. Where $u(t)$ and $y(t)$ time-varying input and output. The characteristic $y(t)=f(u(t))$ is assumed to be non-...
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Is every state space model transformable to transfer function and vice versa?

I'm looking for a mathematical proof or example of non tranformable model, and I couldn't find any.
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What is the correct architecture of quadcopter control?

I want to make a quadcopter flight controller for my University project. Lately I was searching for systematic architecture of control system used by quadrotors. I have implemented one of the ...
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irobot create 2: random changes in driving speed

I am trying to make the Create2 dance a specific choreography. I´m not using the sensors, I just let it drive and turn for a specific amount of time. In general it works fine. But after working with ...
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difference between non-holonomic and linear control systems

I already asked this question in the mathoverflow forum, but no one could answer. Probably it is not a question of mathematics but robotics. I'm struggling with the definitions and differences between ...
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Relation between control and reinforcement learning

Has the relation between Control and reinforcement learning been studied by the scientific community? I would like to read credible studies about each ones pros and cons when it comes to control ...
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What can a Point-to-Point Robot do?

What are point-to-point controlled robots actually good for? Only pick and place tasks? Since continuous path controlled manipulators can do anything a p2p robot can do, plus tasks that require a &...
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PID on DC motor turning on both directions

I have a skid steer robot where I have four individual DC motors with an H bridge so I can control speed and direction. There are also four quadrature encoders with 6000 ticks per revolution. The ...
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Is it possible to control a 5 DOF manipulator in the 6 DOF Task Space?

I am referring to pre-computed torque control techniques that are based on the Task Space dynamic model. Maybe by using pseudo-inverse for the Jacobian and the task space inertia matrix ? Cheers, ...
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Real Time Motion Control [closed]

How is real time control normally handled? Do you run a separate motor control unit which has its own RTOS or is there some other way?
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Cartesian Velocity Control between Two 3D Poses

I am really struggling to understand how to do Cartesian velocity control when 3D rotations are involved. So, below is a very simple example which I am hoping somebody can help me with. Let's say the ...
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output velocity equation of compliance control

I am trying to implement a compliance controller for a robot arm and stumbled upon an existing code snippet where the compliance velocity of the endeffector is calculated by: $v_{out} = v_{in} + \frac{...
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How do I get competent in using c++ for my projects? [closed]

I am a PhD student, working on Sensor Fusion and estimation problems. I would like as I finish my PhD to have acquired sound knowledge in what seems to be the industry norm for working with real ...
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Given this old pin diagram and numbers on this old encoder, what would be a suitable modern encoder to use?

My place of work has recently acquired a Hydraulic Press Break from the 80's. It has a CNC controlled back stop which is driven by a DC motor and Screw drive. The encoder which couples to the motor ...
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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 ...
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problem in understanding this part of the RRTx path finding algorithm

this is a paragraph from the paper of the RRTx algorithm and below it a figure referenced in the paragraph however the No and Nr nodes types are unclear to me what are they exactly ?
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Can ROS be an alternative for a KFLOP or RUMBA Board?

I have a few questions about controlling robot arm motion. I see that some have used Dynomotion KFLOP and other CNC motion controllers to control arms. Some have used Rumba board as well as several ...
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Quaternionic feedback for for cartesian impedance control

I've seen that there are plenty of ways of generating orientation errors with quaternions. But the one I've seen most often is the following: For example, say that for a quaternion $Q = \{\eta, \...
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42 views

Feed both position and speed errors to one single PID

I have seen in the documentation of an old subcontractor's product that the controller of a robotic arm joint was basically feeding error position + error rate directly into one single PID. It feels ...
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Cartesian Impedance control Damping Design (Double Diagonalization)

In the literature, it is often seen that for a system: \begin{align} \Lambda \ddot{e} + D_d \dot{e} + K_d e = F_{ext} \end{align} A dynamic damping matrix is required for a robot to take ...
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HTTP requestes for Robot Teleoperation

I'm new to this forum so I apologise if I disrespect some rules. I am considering using HTTP requests to control a robot remotely. The design problem I am trying to solve is that I would like to ...
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Robust Controls of Quadcopter

Can anybody please guide me about the robust modeling and control of a quadcopter. Where can i find the robust modeling that can be understandable for me as i am a undergraduate student. I am doing ...
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What are the uncertainites in the Quadcopter model for which we make a Robust Controller?

A quadcopter model may have some uncertainties for which we usually use a robust control. Can please someone specifies some uncertainties? like for what kind of uncertainties do we make a robust ...
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Controller Design Using Webots! (Heading, Velocity, tilt,balance)

I am trying to design and implement certain controllers for a robot. I am currently designing controllers for the robot, where it aims to control the Heading, Velocity, Tilt, Balance of the robot. ...
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Measurements of IMU (accelerometer and gyroscope) are drifted or with too much error

I placed my drone on a table (i.e, at rest) and save (using a ROS topic) the IMU readings: As you can see, there's a lot of drift or error. I would expect the $x$ and $y$ acceleration to be 0 (I know ...
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On a multirotor, how effective is braiding of power wires from the ESC to the BLDC Motor(s) in reducing or eliminate emf?

Assuming BLDC motors with the ESC positioned at the 'worst cased' (furthest distance) with longest power wires between the ESC and the motor, will braiding these three wires reduce the EMF that would ...
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Robot dynamic control

This can be a basic question but according to my knowledge I don’t know answer. We can use control system theories to control the position of motor. Considering two motor joint leg it can model and ...
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How can I modeling a simple haptic interface system to obtain results similar to the paper “Time-Domain Passivity Control of Haptic Interfaces”?

I am trying to simulate the experiments in the paper "Time-Domain Passivity Control of Haptic Interfaces", Hanaford and Ryu, 2002, IEEE transactions on robotics and automation vol .18, No1 about the ...
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1answer
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Control a servo (two position 180-degree swing) with an On/Off switch without microcontrollers [closed]

For my application, I need to be able to control a servo with a simple on/off switch. When it's off (pulled LOW), I need to servo to go at -90 degrees and stay there - possibly for a prolonged time. ...
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87 views

Matlab Simulation using Webots!

I am trying to run this youbot ( sample world) from webots, where the controller is implemented in MATLAB, on running the code it pops out the following error seen in the picture attached. I have also ...
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Controller Design using Webots!

I am trying to work on a Digital Twin of a Physical Robot which is used at my uni. I made a rough model of the robot using Webots (Open source). I need to design certain controllers aiming at the Tilt,...
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1answer
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How to create a Complementary Filter for a linearly accelerating body to obtain estimate of orientation in quaternion?

A complementary filter (CF) uses orientation obtained calculated from gyroscope, accelerometer and magnetometer to find a more accurate measurement of orientation. However, when my sensor is ...
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Is it possible to track position using gyroscope and accelerometer without a magnetometer?

I'm looking for help on a project where I will be placing sensor data in 3D space using augmented reality. Most solutions I have found for finding position with an IMU involve the magnetometer, but ...
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Can badly tuned Feedforward still decrease following error?

Let's say we're trying to control the speed of a motor to 20 revs/sec, and we know that our controller output for that speed is approximately 5. We currently have a Proportional controller to drive ...
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What is a low level controller for a quadrotor?

I am studying control systems, and I was reading a paper about quadrotors. In the paper it is said that in the platform of the robot it has to be present a low level controller. But what is a low ...
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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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