Questions tagged [motion]

the action or process of moving or of changing place or position

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What's the difference between the different types of "control"

I've embarked myself into an "action in robotics" journey, and I'm currently having troubles to understand the main differences between the different types of "controls" listed ...
Esteban's user avatar
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Velocity based motion model (dead reckoning)

I'm trying to understand the derivation of the velocity based motion model to implement an EKF: But the problem is, that I cannot find any derivation/explanation. Mostly there is only a visualization ...
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Probabilistic Robotics by Thurn: Velocity motion model. Detailed derivation for eq. 18

In the book, The equation for finding center of circle is denoted in eq. 5.17, which is as $$\begin{pmatrix} x^* \\ y^* \end{pmatrix} = \begin{pmatrix} x \\ y\end{pmatrix} + \begin{pmatrix} -\lambda \...
unwantednoise's user avatar
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Unreachable Velocity in Jerk Limited Trajectory

I've recently been developing a jerk limited trajectory algorithm. I've gone through all the analytical solutions for every profile to find the time optimal solution, and then quantized to the nearest ...
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Dynamical footprint in Nav2

I'm employing the Smac Hybrid-A* Planner along with the Model Predictive Path Integral Controller for point-to-point navigation of an wheel-loader/LHD vehicle. The challenge is that there's a central ...
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Choosing the right BLDC motor and gearbox

I'm having a trouble understanding how to choose the right BLDC motor and gearbox combo for my final project of engineering school. here are the knowns I have gathered so far: gearbox and motor combo ...
T.A's user avatar
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Instantaneous Center of Rotation of Skid-Steering Mobile Robot

Is there a instantaneous center of rotation (ICR) for 4-wheeled skid steering mobile robot (such as Husky , Pioneer 3-AT) if the center of mass is located at the geometric center of the robot? What if ...
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Kinematic model of skid-steering mobile robot (4 wheeled mobile robot)

The kinematic model for skid-steering mobile robot (4 wheeled mobile robot) is where state vector is $q = (x,y,\theta)$, and $\eta = (v,w)$ is the linear and angular velocity of the robot, and $x_{...
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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 ...
Oldmicah's user avatar
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How to find coefficient of friction that will maximize torque?

When using DC motors with a drive wheel (aka "direct drive") to propel a vehicle (e.g. an RC car), force and torque play a role in how efficiently that motor's power is transferred into ...
tniles's user avatar
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In Dynamic Motion Primitives, why we need to approximate f if f_target is given?

I seem to misunderstand something crucial regarding finding the force vector in the process of DMPs: The way I understand it, I should come up with a dataset of trajectories $\{y_i\}_{i=1}^n$, and ...
Hadar's user avatar
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Why aren't more bipedal (or even quadruped) robots made with joints/articulations similar with those found on atmospheric deep dive suits?

The sole reason I'm making this question is due to the fact that such joints/articulations would allow the electric motors to continuously move while the walking motion is performed, instead of the ...
Fulano's user avatar
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Best way to generate a configuration space for a 6 DOF robot

I'm currently working on a motion planner for a 6 DOF robot but I can't figure of a good method to generate a configuration space. The most basic way would be to test every position possible if there ...
Justin M's user avatar
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187 views

Equations of motion with mass attached to end effector and external force

I have to find the equations of motion for the given manipulator: The links of the manipulator are considered weightless and the equations of motion have to be derived by using the Lagrange equations....
Teo Protoulis's user avatar
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Potential FIeld Calculation

We have to implement an algorithm for potential field path planning. I have implemented so far everything for this formula: ...
Alex's user avatar
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Omnidirectional Movement for 3 Wheeled Spherical Omni wheel robot

I was watching James Bruton's video on his spherical omniwheeled robot and he was explaining how to go directly sideways. He explains this from 6:09 to 7:06. I didn't understand how the velocity of ...
DragonflyRobotics's user avatar
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Why isn’t my shaft moving? [duplicate]

When I put my shaft through the vehicle body (small robot) and have the motor attached to it through two rotating gears, the shaft isn’t rotating? I think it’s due to how the hole diameter is the same ...
Ralph Faure's user avatar
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Can we reduce pitch of a lead screw to reduce backlash of the lead screw?

In gear design, the backlash is introduced in the design itself (not by tolerances of manufacturing) to allow free meshing of the gears. The backlash in the design can be minimized by reducing the ...
Khushal Badhan's user avatar
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ICP results as command in odometry motion model

im going through the odometry motion model proposed by Thurn in Probabilistic Robotics famous book and i have some questions concerning the kind of command that we can use. I will explain more my ...
Lotfi Zeghmi's user avatar
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1 answer
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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?
FourierFlux's user avatar
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Name of imitating motion technique in Robotics

This is my first question here and I'm not into this thing at all. I recently saw a movie named Pacific Rim and in that I saw a technique in which a robotic arm imitates human arm(in the beginning of ...
VIPUL TYAGI's user avatar
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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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Maximizing the Coefficient of Friction Between Two Surfaces

I am new to this site so please let me know if I can improve my question. A component of a robot I am designing includes a four-wheeled carriage that travels linearly on an aluminum surface. The ...
grahmW's user avatar
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Can badly tuned Feedforward still decrease steady-state 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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Bump and turn toys: how do they work?

I remember that when I was a kid, in the 1980s, I had some toys made in Taiwan that basically worked like this: they moved forward uniterruptily until they bumped into an obstacle; then they moved ...
user36088's user avatar
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How does one estimate motion from sparse encoders and IMU-Gyro data?

I have a robot which has (for simplicity) only one degree of freedom; it rotates about the z-axis (think like a crane), and has no slip. The shaft encoder delivers data in 0.1° increments, so when ...
oarfish's user avatar
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A powerful pull/rotate device that provides a certain (controllable) force?

I don't know how to call the device I'm looking for (or need to create), maybe you can help me with terminology too so I can at least search.. I want something that either rotates or pulls with a ...
user2520968's user avatar
1 vote
1 answer
33 views

Observed position update after motion of the robot

The equation (14) in this paper, $$ P_{Cj}=RP_{Pj}+T+e_j $$ where $P_{Cj}$ and $P_{Pj}$ are the observed positions of feature $j$ prior to and after the current robot motion, $R$(otation) and $T$(...
willSapgreen's user avatar
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78 views

How to quantify motion?

I am working on a calibration algorithm where the motion is related to the observability of the parameters that I am calibrating. Let's say we have a 6 dof trajectory and wants to quantify its motion ...
Chanoh Park's user avatar
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Problem with UKF weights when calculating predicted state

I'm having troubles implementing a UKF during the calculation of $\overline{\mu_t}$, specifically in this step: $$\overline{\mu_t} = \sum_{i=0}^{2n}w_m^{[i]}\chi_t^{*[i]}$$ My problem I'm facing is ...
oswinso's user avatar
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3 answers
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What are the equations of a s-curve position path?

I have a decoupled mechatronic system with two motors. I want for each motor to give a s-curve path as reference. You can see in the image below the position path, velocity and acceleration. All ...
Metalzero2's user avatar
1 vote
1 answer
308 views

Controlling YuMi robot by serial port

I'm trying to control the YuMi robot arm by a serial port. The serial port will give the information on what direction the end-effector should move and what is the velocity. What I would like to ...
user22088's user avatar
2 votes
0 answers
132 views

Wheeled Mobile Robot State Estimation Model Using Odometry

I have a process model update that follows the form: $$ \mathbf{x}_{k|k-1} = \mathbf{x}_{k-1|k-1} + \delta \mathbf{x}_k, $$ where $\mathbf{x}_{k-1|k-1}$ is the posterior estimate from the last ...
joe.dinius's user avatar
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0 answers
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Lost on SEIF Slam repeated update landmark

I am working on Sparse Extended Information Slam. I take the reference from Probabilistic Robotics, by Dr.Sebastian Thrun (Chapter 12,page 303). I have some doubt about the implementation of the ...
Encipher's user avatar
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3 votes
1 answer
212 views

SEIF ,online version of Graph slam create doubt in Motion Update state

I have a thesis work about Graph Slam The GraphSLAM Algorithm with Applications to Large-Scale Mapping of Urban Structures I try to implement it with the help of this paper but during the ...
Encipher's user avatar
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2 votes
2 answers
541 views

Ackermann Motion Model Does not Drive in an Arc, but Turns on the Spot

Im trying to implement an ackermann motion model which estimates the x,y and theta for a robot I have. I have a gazebo simulation running which publishes a steering angle for the virtual tricycle ...
Marc HPunkt's user avatar
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2 answers
81 views

Motion Profiling for Decreasing Energy Consumption

I am attempting to minimize the energy consumption used by an electric-motor-powered car given the speed restrictions: $$\text{speed}: [v_{\text{min}},v_{\text{max}}]$$ Currently, we are utilizing a ...
andrewgazelka's user avatar
2 votes
2 answers
688 views

Explanation for exponential coordinate of rotation

From figure above, suppose a three-dimensional vector $p(0)$ is rotated by an angle $\theta$ about the fixed rotation axis $\omega$ to $p(\theta)$. Here we assume all quantities are expressed fixed ...
npkp's user avatar
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Jacobian of kinematic IMU Model

I have the following problem: given two Input Vectors $x = \begin{pmatrix}x\\y\\z\\v_x\\v_y\\v_z\\q_1\\q_2\\q_3\\q_4\end{pmatrix}$, $u = \begin{pmatrix}a_x\\a_y\\a_z\\w_x\\w_y\\w_z\end{pmatrix}$ time $...
Leo 's user avatar
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1 vote
1 answer
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Probably basic question about how control a DC motor

over the past weeks I was trying to figure out how use the information from hall sensor to control a DC motor. Basically this is the motor which I'm using: https://www.servocity.com/32-rpm-hd-premium-...
Leonardo Jared R S's user avatar
4 votes
2 answers
567 views

Motion planning from a given path

Many articles reference algorithms such as A*, PRM or RRT based planners to motion planning algorithms which seems unreasonable since it is still necessary to parametrize found path with time.I wonder,...
Long Smith's user avatar
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1 answer
913 views

Are S-Curve (constant jerk) motion profiles significantly better than constant acceleration?

I've been investigating S-Curve motion profiles for CNC router and 3D printer applications, and haven't come across any definitive source that says an S-Curve profile is necessary in any application. ...
Ben Porter's user avatar
1 vote
0 answers
198 views

My robot arm vibrates during operation. Why?

Introduction: I have modeled my 5-DOF robot arm in a simulation environment to test trajectories for my physical model. I have export the joint variables from the simulation as a .csv file. Then ...
csg's user avatar
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1 vote
1 answer
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Quadrotor SE3 Controller: Calculating Rd_dot

I am trying to simulate and implement the controller in the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). I have the dynamics implemented, however I am stuck at one part in the ...
danny's user avatar
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0 votes
2 answers
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Quadrotor Dynamics: Calculating angular velocity of quadrotor

I am trying to simulate and implement the controller of the paper Geometric Tracking Control of a Quadrotor UAV on SE(3). To do this I need to first implement the dynamics of the quadrotor. According ...
danny's user avatar
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2 votes
1 answer
203 views

Why don't bipedal robots ever feature natural movement?

I'm a programmer and I've decided to make some bots for fun. I might start with wheels but my ultimate goal is to make bipedal robots. To that end I first decided to watch a bunch of videos of such ...
xendi's user avatar
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6 votes
3 answers
5k views

What does SE mean in robotics literature?

I've come across the abbreviation SE several times recently. I know it has to do with the pose of the robot, and the degrees of freedom. Most recently I found it on page 8 of this paper: D. Kragic ...
Preston Roy's user avatar
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2 answers
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How can I draw with a 3 DOF RRR arm ,I have done the Forward and Inverse KInematics

Heres the Matlab code, I start with x and y and when I pass it through IK and Fk I get back the correct x and y thus I am confident that IK and Fk are correct. ...
Abhilash V J's user avatar
1 vote
0 answers
89 views

Which Trajectory representation for optimization

I'm strugling on that problem for a while, so any help is welcome. I need a trajectory representation that is performant for optimization, i.e. I want something that computes quickly. The function I ...
JulesW's user avatar
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1 answer
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Thrust and Torque on Quad Rotor

I am a beginner on Drones. I would like to understand the how each motor contribute to thrust on the whole drone. And what is the direction of torque created on each propeller. Everywhere I find a ...
Dharma's user avatar
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