Questions tagged [control]
A method or device to manage, command or regulate some part of a system.
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questions
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Fuzzy Path Planning for an Unknown Environment
I have a problem to programming on Matlab the path planning fuzzy in an unknown environment I am using a fuzzy toolbox for fuzzy rule
How to do obstacle avoid by Matlab demo program
How to reach the ...
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1answer
8 views
sensors that can be used to calculate position of a moving object
While i am designing for a chair that can follow human, i found out that i need sensors to calculate the position of that human in range of 5 meters what such sensors can fulfil that purpose.
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Hi. I really need help on this robotics coordinate practice problem
I have got stuck on this problem for 2 days. I think I got part a down but as for part b-d. I am not sure what all those parameters (theta 1, d_2, theta t) are refering to since the schematics is not ...
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1answer
38 views
Robots Following Robots with Safety Distance Planning and Coordination
I have two robots, I wish for the second robot to follow the first one while keeping a constant distance d_safe between them. I am trying to implement a PID ...
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MAVLink data stream to third-party system
I'm a completely beginner with pixhawk and MAVLink. So I want MAVLink (via AP Mission Planner) to send vehicle data e.g. attitude etc. in real-time to a third-party system that has a built-in ...
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How to perform a cart-pole swing up task using MPC?
I originally thought this was a really simple problem. However, to my surprise I did not find any resource talking about it, the only thing I found was that using Matlab's nonlinear MPC toolbox you ...
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Find viscous friction for DC motor transfer function
How do I find the viscous friction for my DC motor without measuring the input current and output torque.
I have to do a theoretical model on simulink and can't find any answers on how to find it
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2answers
48 views
How to investigate the relation between planning frequency and control response?
I have a speed control system which is part of a hierarchical planning and control stack. The final output of this system is torque and the input is desired speed. The system is experiencing some ...
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Is there a way I can achieve Torque control from pulse control?
I am using the Contec SMC-8DL Motion control card to control the Oriental Stepper motors via the AZD-C driver. The Contec helper functions only allow for sending pulses to the driver, is there a way ...
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1answer
46 views
How to find angular velocity using pure pursuit algorithm?
I have implemented the pure pursuit algorithm for my differential wheeled robot as described in the following paper:
http://www.enseignement.polytechnique.fr/profs/informatique/Eric.Goubault/MRIS/...
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1answer
54 views
How to choose closest angle when crossing -180 degrees
I'm applying a PID for position control on a diff drive robot, got the angles (orientation )between -pi and pi. It works fine until it needs to change its orientation from (let's say) -170 degrees to ...
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47 views
Is it possible to solely use a P-controller for velocity control?
Let's say I want a robot to run at a certain speed. I have one motor attached to each robot rear wheel. The feedback value to the controller comes from an encoder, which outputs pulses per time unit, ...
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53 views
Velocity-Control of a manipulator without a dynamic model
I have a five DoF robot. Each axis is connected to a cylinder. You can send PWM values to each cylinder and you are able to read out the position values of each cylinder which makes it possible to ...
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1answer
57 views
Help on the Walking without thinking about it paper!
I was reading the paper, which you can find: https://hal.inria.fr/inria-00567668/document. I got so confused with equation (33) and (34), it seems like instead of an equal sign in eq.(33) on the left ...
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1answer
47 views
Do hobby servos respond to step inputs with a step in torque?
I'm designing a piston that I need to expand a few cm in <100ms to load energy into a spring-mass system with around a pound of force (as shown below). Based on power specs alone, high-end hobby ...
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2answers
254 views
Impedance Control vs Position Control
I have been reading up on impedance control, and several sources have stated that it is much safer than position control. However, frustratingly, none of these sources have explained why this is. So......
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1answer
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How to estimate gradient of Jerk
A trajectory is described by a position vector, i.e., traj = $[q_0, q_1,...,q_n]$. The objective is to minimize the jerk of the trajectory.
I am referring to this code to understand how the gradient ...
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1answer
31 views
Control signal of an LQR Controller
I'm working on building an LQR for a system which consists of a ball in a vertical tube, a fan is situated at the bottom of the tube and a distance sensor is at the top, a raspberry Pi is used to send ...
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Path curvature in kinematic bicycle model
I'm trying to develop an understanding of the control law for longitudinal and lateral control for self driving cars. While doing so, I came across the kinematic bicycle model which is used to derive ...
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1answer
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How to simulate a system output with a sine wave input?
I wish to simulate the output of a certain gear system I have. How the gear system looks isn't particularly important to the problem, I managed to get the differential equation needed from the ...
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Kalman filter for visual tracking of a ball sliding on a gutter
I'm working on a project where a robot needs to keep a ball at a desired position on a gutter. The gutter is fixed at one end and held at the other end by the robot’s ...
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1answer
55 views
Does the Grbl have S-curve or harmonic velocity profiles?
I'm working on a machine and the position has a high impact by the jerk and acceleration of the machine. I'm using Grbl for my machine. Does Grbl has S-curve or Harmonic velocity profiles?
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1answer
63 views
What can cause yaw rotation on a multirotor when yaw control is disabled?
Let's assume that I assembled a multicopter (quadcopter, hexacopter or octocopter) and let's say that I disable yaw control on it while roll and pitch controllers are enabled.
Now let's assume that I ...
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2answers
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PID Control: Is adding a delay before the next loop a good idea?
I am implementing PID control in c++ to make a differential drive robot turn an accurate number of degrees, but I am having many issues.
Exiting control loop early due to fast loop runtime
If the ...
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Is Image Based Visual Servoing a non-linear controller?
Is Image Based Visual Servoing a non-linear controller? I think it is as the Image Jacobian has square terms of u & v (image-plane coords).
Where $p_u, p_v$ are the width & height of each ...
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1answer
24 views
Dynamics with error term
How do the dynamics of a system change when an error term is introduced?
For instance, if I have a system (computed torque control - robot manipulator):
$$M\ddot{q} + C\dot{q} + G = u$$
and $e = q-q_{...
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3answers
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How to obtain the state space representation of a computed torque control system?
Assuming I have a system:
$$
a \, \ddot{x}_1 + b \, \ddot{x}_2 + c \,\dot{x_1} + d \,\dot{x_2} + e = u_1 \\
f \, \ddot{x}_1 + g \, \ddot{x}_2 + h \,\dot{x_1} + i \,\dot{x_2} + j = u_2
$$
How would I ...
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2answers
51 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..
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1answer
40 views
How do I compute the feedforward terms in a control law using Matlab?
I have the following situation. I have computed the linear and angular velocity which are the controls for a mobile robot, which have the form:
$v_d=v_{fb}+v_{ff}$
$\omega_d=\omega_{fb}+\omega_{ff}$
...
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1answer
151 views
How can I define the saturation function in Matlab?
I would like to write a Matlab code for an angular velocity of this type:
$\omega=\omega_{fb}+sat(\omega_{ff})$
where $\omega_{fb}$ is a feedback angular velocity and $\omega_{ff}$ is a feedforward ...
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2answers
131 views
How to consider gravity for the state space modeling
I'm trying to find the state-space model of the following ball-in-tube system.
I designed the SISO system, with the h(ball height), w(angular velocity of propeller), and I(current) as the system ...
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1answer
32 views
Control method advice for Markov (?) process
I'm experimenting with a device for tuning piano strings. It attaches to the piano's tuning pins and turns them slightly by applying a torque impulse. It is a semi-automatic process, handled by a ...
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1answer
37 views
Matlab code to take time derivatives
I have a velocity command, which is:
$v=k_1\rho cos(\alpha)$
where each quantity $\rho$ and $\alpha$ depend by the time.
I would like now to take the time derivative of this, in order to use it as ...
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1answer
32 views
What is the difference between The state-space equation and The configuration-space equation
The craig(p.180) states that equations can be made to represent the dynamic equations. The first one being the state space equation.
$\tau=M(\Theta)\cdot\ddot{\Theta} + V(\Theta,\dot{\Theta}) + G(\...
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2answers
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Is it better to use Jacobians to compute IK when a closed form for IK is available?
I hope that my question is not too stupid ... but I have a hard time to understand why Jacobians computed from forward kinematics would allow a better and smoother control than using pure inverse ...
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1answer
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How do I apply a disturbance observer to a mobile robot?
I have to design a observer to estimate disturbances which are applied to a unicycle model. So, the unicycle model with disturbances is:
$\dot{x}=v cos\theta + d_x$
$\dot{y}=v sin\theta + d_y$
$\dot{\...
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2answers
38 views
Reliably enabling/disabling a PID loop via FSM in a microcontroller
I have a PID loop for a small vehicle implemented in a microcontroller. Currently the PID loop is implemented in a timer interrupt. I want to implement an FSM that will have states that enable or ...
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1answer
183 views
How can I solve this block diagram problem?
I practiced various examples of block algebra and I came across this example where I have to reduce the block diagram. The problem now is that I have there successively set branching points and sum ...
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1answer
38 views
Cartesian control for $z$ vector of end effector frame to point towards a specific direction
Consider a robotic manipulator with 7-DOF (all joints are revolute) that accepts joint velocities as execution commands. What I am trying to achieve is the following:
I want to calculate the ...
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1answer
56 views
Problem designing acceleration inputs controller
I am reading this paper: https://www.researchgate.net/publication/224635390_The_motion_control_problem_for_the_CyberCarpet
in which is implemented a cartesian regulator to bring the position $(x,y)$ ...
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1answer
53 views
Motion profile and Motion control scheme, how do they interact?
I'm studying motion control and I start with the simplest case, I have to go from A to B in a straight line using a trapezoidal motion profile.
I understand that in a real case, due to the fact that ...
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1answer
31 views
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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2answers
110 views
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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1answer
92 views
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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3answers
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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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1answer
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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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1answer
39 views
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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1answer
55 views
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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1answer
51 views
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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1answer
30 views
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 ...
