Questions tagged [control]
A method or device to manage, command or regulate some part of a system.
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Developing a robot using mecanum wheel to follow specific path accurately
I am developing a robot using esp32, mecanum wheel, stepper motor and mouse sensor. The robot runs 1000mm forward, 10mm sideways (right side without turning), 1000mm backward, 10mm right and cycle ...
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How are exoskeletons controlled?
It is my understanding that there are 3 fundamental control methods : velocity, position and torque.
In exoskeletons meant to augment an healthy user's strength, a typical control method used is ...
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What’s this gearbox called? [closed]
I took an apart a child’s toy because it looked like it had a neat gearbox in it, it did. The problem is I have no idea what type of gearbox is and I wanna see more things used with it.
It rotates ...
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How do you calculate this integral term in this PI Controller Formula?
This formula is the PI Control given in Eqn. 11.6, Pg. 419 of Chapter 11 in book Modern Robotics by Kevin M Lynch and Frank C Park.
Here,
Vb is the twist ==> Vb = (angular velocity, linear ...
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Inverted pendulum LQR controller using motor
In my lab, I am trying to balance an inverted pendulum using simple LQR. To balance the arm I am using a DC motor. Now I have the A, B, C, D matrices. Using those I am able to find the feedback gain '...
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How to exchange commands and states between hardware interfaces (to generate a CAN message)
I have a robot with ackermann steering and front 2 wheel drive. The vehicle already has all the mobility controls executed by the ground mobility module. The autonomy layer (the computing unit) will ...
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How to control the position of a load shared between two (servo)motors?
I want to position-control an axis combining the action of two DC servomotors - one of them alone is not powerful enough; I had those available and preferred not to buy a new one.
I have not the ...
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Steering wheel angle control
I am working on an autonomous vehicle's control, specifically the steering angle control.
Knowing that I used kinematic bicycle model, my questions are:
How do I choose the actuator for my steering ...
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How do I calculate reference trajectory for a robot following a parabolic path at a constant speed?
I have a 3 DOF robot arm and have been tasked with making it follow a path of $y=6-x^2$. Normally to compute the reference trajectory, I would simply create a linearly spaced vector of $x$ values and ...
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Velocity control with position setpoints
I'm trying to control the toyota HSR with a higher level whole-body controller that computes velocities, but the robot only offers JointPositionInterfaces in it's ros_control HardwareInterface ...
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Derivative Block Diagrams
I am a newbie in Control Theory. I am solving an exercise found on-line. I do not expect anyone to solve it for me. I would just ask for a clarification about the block "p+a". I suppose it ...
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Webots - Copy Paste a Robot
In Webots: I want to do a Predator/Prey simulation and need to spawn the exact same robot when an event occurs. How do I copy/paste a robot I have in my world scene tree. I build it my self therefore ...
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Where should I write and call GPIO port connection in the hardware interface in ros2_control for control of robot movement on Raspberry Pi 4?
I am using ROS 2 Humble on Raspberry Pi 4(Ubuntu 22.04 OS).
I am trying to build 2-wheeled diff-drive mobile robot and using ros2_control for controlling, but I'm ...
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Ros control pid gives different input than expected
I am trying to match the trajectory i am getting from gazebo simulation using ros_control and matlab for a simple pendulum which rotates in the horizontal plane (so no gravity, no friction and no ...
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PD control with gravity compensation
Given the robot dynamics of the form
$$M(\theta)\ddot{\theta}+C(\theta, \dot{\theta})\dot{\theta}+G(\theta)=u$$
where the notations have the standard meaning ($M$ is the inertia matrix, $C$ is ...
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How to compute orientation error for a Puma end effector
i hope that you'll be ok!
I'm trying to control a Puma robot using the inverse kinematics in Matlab.
I used unit quaternions to express the orientation of End Effector frame and orientation of desired ...
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When express a first-order system as a block diagram with feedback?
I've seen in many places that a first-order system is depicted as a block diagram using an integrator. For example, this figure comes from https://www.tutorialspoint.com/control_systems/...
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Light weight one axis hinge name/recommendation
I'm attempting to build a crow that can stay upright even when its perch tilts. For that I need to have some single axis hinges (not u-joints). I'm using 3mm rod for my internal supports and am ...
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Differential Inverse Kinematic Controller ROS
Inverse differential Kinematic - Problem with Orientation
Hey guys,
currently I am working to control my UR-Robot. My goal is to control the robot with inverse differential kinematics :
1.) vel_q = J^...
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How to calculate Exponential coordinates of end_effector from Transformation matrix
I want to know Exponential coordinates of end effector $\text{S}\theta$(6-vector) from end effector transformation matrix. I calculated the transformation matrix of the end effector from the forward ...
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MPC over a distribution of states
What are the approaches to MPC when you have a distribution over your current state along with the process model?
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Question about Impedance control in The Modern Robotics: Mechanisms, Planning, and Control
Impedance equation In 11.7.1 section $\tau = J^T(\theta)(\hat{\Lambda}(\theta)\ddot{x}+\hat{\eta}(\theta,\dot{x}) - (M\ddot{x}+B\dot{x} + Kx))$ is actually means $\tau = J^T(\theta)(\hat{\Lambda}(\...
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Impedance control algorithm in The Modern Robotics: Mechanisms, Planning, and Control
I am studying The Modern Robotics: Mechanisms, Planning, and Control (by Kevin Lynch, Frank Park and Evan Suma). I am trying to implement Chapter 11.7.1 Impedance-Control Algorithm of the book with ...
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How to use Supervisor along with regular libraries
In my Webots simulation, I am trying to use a supervisor in order to get parameters from other nodes to then have a motor respond by increasing or decreasing its torque, to which I have written the ...
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Recording controller output
I am a new to the field of control systems.
In real life systems, such as process industry or continuous manufacturing, where large number of feedback control loops are present - is controller output ...
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Is Luenberger observer applicable in practical systems?
I have tried to find out about this from quite a few sources but it still remains unclear to me. I know that the Luenberger observer is applicable for a deterministic system with known control inputs ...
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PID controller error calculation when the setpoint and the process variable both grow over time
Suppose I have a robot which can perform some work and be rewarded with a point 50-70% of the time. I want a different number of points to be collected every hour of the day. This is modelled using a ...
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How could you have controllers communicate with each other?
I have been attempting to have two controllers be able to access information from each other in a way that is similar to object-oriented programming in UNITY, however, I have constantly had problems ...
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Controlling a system in a particular direction
In Discrete-time Control Engineering by Katsuhiko Ogata, it is stated that "A necessary and sufficient condition for complete state controllability is that
no cancellation occurs in the pulse ...
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How does the lightsensor values work? Lightsensorvalue into Percentage
In Webots: I try to build a Braitenberg vehicle so that when it receives light information through the ligh sensors it drives either away or towards the light. I used an ePuck and tried to just ...
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simulating transfer function with python
I've been trying for quite a while to simulate a transfer function using control library on python but I keep getting the wrong result, does anyone know the reason?
This is what I get:
This is what I ...
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Sampling in non-parametric distribtution
I am currently working on a package in C++ to easily implement different Statistical Filters, and after implementing various versions of the Kalman Filter I decided to start working on the Particle ...
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Object tracking using PTZ camera with PID Controller
I'm trying hard to implement an object-tracking algorithm on a PTZ camera. For this, I have chosen to use a PID controller for error correction.
In my case, the set point value is the center of the ...
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Trajectory tracking for a robotic arm
I want a robotic arm to do trajectory tracking in the joint space. Suppose the waypoints are
$$
[t(0),q_1(0),q_2(0),q_3(0)],\\
\cdots,\\
[t(n-1),q_1(n-1),q_2(n-1),q_3(n-1)]
$$
I already know that I ...
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cartesian velocity control loop implementation
I'm using ROS (noetic) to intuitively control a franka manipulator using the panda_robot package for the simulation.
I've set up an extended kalman filter which fuses the following measures:
IMU data:...
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Finding error in euler angle from quaternion
I'm currently working on creating a ROS controller package for franka arm, which I choose to implement a feedback linearization controller that works as following:
Assume we have a planned trajectory $...
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Can we show converenge for a variant of inverse dynamics controller?
I was wondering if it is possible to show that a variant of the inverse dynamics controller
$$\tau = \mathbf{M}(q)\ddot{q}^\mathrm{des} + \mathbf{K}_pe + \mathbf{K}_d\dot{e} + \mathbf{h}(q, \dot{q})$$
...
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Record and playback stepservo backdrive
I have a stepservo motor with a high precision encoder. I'd like to use it in "teach" mode where I can move it around with my hand (backdriving), and then playback whatever motion I did.
...
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PID controller feasibility
I'm trying to control a hybrid inverter to manage a selfconsumption mode bypassing its native mode - meaning to distribute power coming from solar and into/from battery to home consumption and grid.
...
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Occupancy grid height
I need to create an occupancy grid (2D) from pointcloud but i need to show also the height at every cell with colors. Right now i know that the occupancy grid is only on grey color, there is an option ...
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Balance 2-wheels robot without making it drift forward/backward
I'm trying to design a controller to balance a 2-wheels robot (around 13kg) and making it robust against external forces (e.g. if someone kicks it, it should not fall and not drift indefinitely ...
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What is the meaning of joint space and configuration space and task space?
I'm reading an article about teleoperation systems and it talks about three spaces that include joint space, configuration space and task space frames. I do not know what these are, can you explain?
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Kalman filter problem with the output
i want to use kalman filter to estimate my phone position, the measurments data is at this point just the accelerometer and the sampling rate is 3ms, i used the library pykalman, i have also wrote my ...
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Superposition in state space equation with multiple harmonics in the inputs
I have a question related to the superposition in state space equation. Suppose I have a state space equation below
\begin{equation}
\frac{d}{dt}X = AX + B\begin{vmatrix}
u_1(t)\\
u_2(t) \\
\end{...
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why it is a dissipating term and is the second order?
corresponding paper
why it said that $-\lambda \frac{|\dot{x}|\dot{x}}{2}$ is a small second order dissipating term ?
For a linear second order system, the velocity is a dissipating term, because I ...
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how the two equatoin are linearized
corresponding paper
Question1: how the equatoin 3 is linearized in the neighborhood of the equilibrium point $x = x_{sp}, \dot x =0 $
Question2: how the equatoin 12 is linearized in the neighborhood ...
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Best way to Inculde System Characterstics (e.g. Laplace Equ.) in ODE for building Control Strategy
Let's consider the following ordinary differential equation (ODE):
$$
\begin{align*}
\frac{\partial x}{\partial t} &= f(x,u)\\
0 &= g(x,u)\\
y &= h(x,u)
\end{align*}.
$$
We denote $x\in \...
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Cascaded PID controller implementation
For a project I am building and programming my own flight controller. I have seen the implementation of a single loop PID controller. But after doing some more research I've found that a cascading PID ...
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Move a Simulated Quadcopter in a straight line
I'm trying to move a quadcopter in a simulator from (x0, y0) to (x, y) in a straight line at a constant speed. The simulator takes x and y inputs in m/s. Altitude as an input is a constant value in ...
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3-links Robot Dynamic PD Computed Torque Control
I am designing the PD control of 3-links robot using Simulink.
I can't figure out what to do in the 'Robot' block to get the acceleration d_qq back to calculate the error.
What is happening in this '...
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