Questions tagged [motion]

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

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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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32 views

Calculating Translation and Rotation in Tool Coordinate System

I have a 6-axis robot that moves from P1(x1,y1,z1,q11,q12,q13,q14) to P2(x2,y2,z2,q21,q22,q23,q24) with tool offset T(x,y,z,q1,q2,q3,q4). I know the base coordinates and orientation of both positions. ...
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How is the motion calculated in freeform 3D tube bending?

I have seen 3D freeform tube bending in videos such as this, this, and this. I would like to ask how the motion of the bending orifice is calculated? Does it involve Jacobian?
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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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2 votes
1 answer
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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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1 vote
1 answer
63 views

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
78 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....
1 vote
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42 views

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
223 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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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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50 views

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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43 views

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 ...
1 vote
1 answer
84 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
75 views

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
179 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 vote
1 answer
41 views

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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2 answers
97 views

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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1 answer
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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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2 votes
3 answers
52 views

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
28 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 $T$(...
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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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1 vote
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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
4k 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 ...
1 vote
1 answer
280 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
126 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 ...
2 votes
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46 views

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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3 votes
1 answer
187 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 ...
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2 votes
2 answers
457 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
77 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 ...
2 votes
2 answers
612 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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1 answer
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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 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-...
4 votes
2 answers
500 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,...
0 votes
1 answer
778 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. ...
1 vote
0 answers
188 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 ...
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1 vote
1 answer
111 views

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
988 views

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
148 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 ...
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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
582 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
465 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
660 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
529 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 ...
4 votes
2 answers
822 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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