Questions tagged [motion]

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

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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 ...
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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 ...
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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 ...
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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 ...
2 votes
1 answer
64 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....
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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: ...
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1 answer
169 views

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 ...
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28 views

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 ...
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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 ...
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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 ...
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1 answer
73 views

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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4 answers
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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 ...
1 vote
1 answer
170 views

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 ...
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1 answer
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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 ...
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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 ...
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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 ...
1 vote
1 answer
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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 $T$(...
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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 ...
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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 ...
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2 votes
2 answers
3k views

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 ...
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1 answer
271 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 ...
2 votes
0 answers
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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 ...
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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 ...
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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 ...
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2 votes
2 answers
448 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 ...
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2 answers
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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 ...
2 votes
2 answers
589 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 ...
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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 $...
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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-...
4 votes
2 answers
477 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,...
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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. ...
1 vote
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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 ...
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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 ...
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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 ...
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1 vote
1 answer
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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 ...
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6 votes
3 answers
3k 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 ...
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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. ...
1 vote
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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 ...
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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 ...
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3 votes
2 answers
559 views

Compensation for IMU mounting misalignment

I have an MPU6050 IMU and I would like to mount it on an FSAE car and use it to measure the yaw, pitch, roll, and angular velocities as it drives. As it's impossible to mount it perfectly flat and ...
1 vote
2 answers
1k views

Estimating yaw angle and yaw rate for a frontal vehicle

I would like to know if it is possible (and if it is possible how can it be done) to estimate the yaw angle and yaw rate of a vehicle in front of me knowing the following information: -my speed (x,y,...
0 votes
1 answer
413 views

Computing Yaw angle from position and velocities

I have an object to whom I know the x,y,z position, length, width, height, and x,y velocities. Is there a possibility to compute the yaw angle from this information?
3 votes
2 answers
592 views

Motion planning and robot controlling

I am stuck with understanding how can I make my robot move along planned path. For instance, if we have a grid map of an environment and applied, for example, A* to plan a path then after that we have ...
2 votes
2 answers
520 views

How to relate forward kinematics into PWM/speed?

I am having a hard time understanding how to relate forward kinematics to things one can control in a robot like PWM and reading encoder values. For example, how to relate the encoder values from ...
3 votes
2 answers
808 views

State estimation of mobile robot

For a mobile robot - four wheels, front wheel steering - I use the following (bicycle) prediction model to estimate its state based on accurate radar measurements only. No odometry or any other input ...
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1 answer
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Step size in numerical differentiation

I get position information and a corresponding timestamp from a motion tracking system (for a rigid body) at 120 Hz. The position is in sub-millimeter precision, but I'm not too sure about the time ...
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What type of actuator should I use? [closed]

I need to find out if There is a way to get at least 60 Hz of linear Motion with at least 5 mm of stroke that I intend to make linear persistence of vision device(not rotating one)It must be small and ...
0 votes
1 answer
987 views

Finding cubic polynomial equation for 3 joints

My professor gave us an assignment in which we have to find the cubic equation for a 3-DOF manipulator. The end effector is resting at A(1.5,1.5,1) and moves and stops at B(1,1,2) in 10 seconds. How ...
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