Questions tagged [trajectory]

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Rigorous terminology clarification - Path Planning, Path Following, Trajectory Planning, Trajectory Following and Motion Planning

I am asking this after having gone through quite a bit of literature and hope that it's not a repeat question. I would like to know proper mathematical notion that clearly defines a Path and a ...
Manish'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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Riding a robot model in Gazebo along a straight, curved path with feedback on a Raspberry running ROS

please be kind and advise how to implement the following: I have a computer with ROS and Gazebo in which I have a robot model in URDF format, I need this model to go on a straight/curved path(straight/...
Perry's user avatar
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UR10 in self-destruction mode for certain trajectories

I am using a UR10 robot with official drivers with ROS1 (noetic) and python. I coded a trajectory generator that creates waypoints. These are also used by a trajectory server and sent to the robot. ...
Florian Schneider's user avatar
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DWAPLANNER in ROS for a person-following robot: Footprint and costmap?

I'm currently working with the DWAPLANNER for a person-following robot in ROS, and I'm eager to gain a deeper understanding of how this planner incorporates a robot's footprint into trajectory ...
Niklas 's user avatar
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Trajectory waypoints are not exactly the same as joint positions. How to find the closest waypoint?

I'm trying to implement a function to pause the execution of a trajectory, and then re-plan a trajectory following the remaining path. The framework I'm using is moveit noetic. ...
L.Towson's user avatar
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Save robot trajectory as a single figure/image

I would like to show the path planned by moveit2 as a figure in a paper I'm writing. I've seen figures with multiple semi-transparent manipulator arms showing various stages of a certain trajectory, (...
clemfandango's user avatar
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Path and trajectory planning for a holonomic drivetrain with non zero starting velocities

What path planning algorithms are typically used for holonomic drivetrains that can avoid collisions while also starting with non zero velocities. I am working on a project where I am planning to have ...
Henry Mahnke's user avatar
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3 answers
134 views

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 ...
Daniel Ogden's user avatar
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How to avoid Cusps and Corners when generating spline?

Here I wrote Qubic spline trajectory generation. The following are the result. Spline that generated Curvature of the spline Yaw angle changes According to Figure 02, there is a sharp change in yaw ...
GPrathap's user avatar
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Smooth a timestamped series of translation and quaternion samples

I have a rosbag of transforms (of type TransformStamped) I'd like to smooth a small amount without altering the overall trajectory much, just reduce the higher ...
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Trajectory generation for robotic manipulator using trapezoidal velocity profile in MATLAB

I am trying to write code in MATLAB to generate a trajectory for a scara manipulator in the robot operational space with trapezoidal velocity profile for each segment passing through 5 waypoints using ...
Robotics_Enthusiast's user avatar
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3 answers
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Designing S-Curve velocity profile for given Distance

I'm trying to create a high-level API for controlling a drone, where I tell it how far I want it to go (eg. moveForward(10)). The SDK allows me to give the drone an ...
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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 ...
eason's user avatar
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Trajectory optimal for quadcopter

I have defined a quadcopter that I control with a PID controller. The dynamics that define it are such. $T=mg+m\ddot{z}$ $\theta=\frac{\ddot{x}}{-9.82}$ $\phi=\frac{\ddot{y}}{9.82}$ As you can see I ...
Hamzalihi's user avatar
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Joint space trajectory script unclear

I have a script provided by The MathWorks Inc. that makes a robot end-effector follow both a task space and a joint space trajectory through several waypoints. These trajectories are then plotted in ...
user463102's user avatar
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Decidability of Pursuit-Evasion games and self driving cars

I was wondering if there is any theory describing the decidability of a continuous pursuit-evasion game with constraints. Scenario: Two cars approach each other on a street with two lanes. Let's say ...
amh23's user avatar
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Why is a joint space trajectory unable to deal with operational space obstacles?

I have found several sources that state that a Joint space trajectory model is not capable of dealing with obstacles in the manipulator workspace. These sources include: slide 10 of "Manipulator ...
user463102's user avatar
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Matlab smooth transition between stored configurations (rigid body tree robot )

I currently have a few joint configurations stored for a robot model in Matlab. When I play back and show the robot in different configurations, there is of course no smooth, but abrupt transition. Is ...
Veronique's user avatar
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Is there any need to guarantee the duration of one planned trajectory is an integer times rather than a decimal times of interpolation period Ti

Take double S of velocity profile for example where the seven segments exist. Given the desired displacement s, the constraints ...
eason's user avatar
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How to design a PID controller for boat?

I have a boat with two trusters and a trajectory planner which is based on the bicycle model. In order to control the boat, the linear velocity of each truster has to be provided. The following ...
GPrathap's user avatar
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Relative scale problem

I am doing Monocular Visual Odometry, and I have problem with relative scale. Most of the time its value is between 0.8-1.1, but sometimes it goes crazy and it has value 3,4 and once it had value 25. ...
Cluv's user avatar
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2 votes
2 answers
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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 ...
user1433734's user avatar
1 vote
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Quadrotor Smooth Trajectory optimization

I'm currently following a course on coursera on quadrotors, and i'm currently focusing on the trajectory planning mechanism. In the course, it's said that one of the criterias when planning a ...
Mssm's user avatar
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1 answer
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Trajectory generation equation from jacobian and inverse kinematics

I just built a 4 DOF Articulated manipulator with open-loop servo motors and the servos signals are generated using a micro-controller. I followed the Angela Sodemann's videos on YouTube, I calculated ...
Zzz's user avatar
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1 answer
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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 ...
GPrathap's user avatar
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2 answers
284 views

Generate a Trajectory from GPS coordinates

How would I generate a trajectory (e.g. minimum snap/jerk/acceleration) for a quad rotor between GPS coordinates? In all the examples that I have seen, they assume that the x,y positions are in meters ...
Brien Crean's user avatar
1 vote
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25 views

Can I relate trajectory generation to differential inverse kinematics?

I am wondering how (if) one can translate trajectories of translation matrices to joint velocities? I'm reading the notes of Russ Tedrake's class on manipulation. One part of the notes concerns a ...
fabian's user avatar
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Sinusoidal trajectory of each cartesian coordinate for the end effector

Consider a 7-DOF robotic manipulator. I want the end effector to follow a predefined trajectory and suppose I care only about the position and not about the orientation. So, the rotation part of the ...
Teo Protoulis's user avatar
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1 answer
118 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 $(x,y)$ ...
J.D.'s user avatar
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3 votes
1 answer
607 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 ...
Ugo Mela's user avatar
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2 answers
87 views

Trajectory planning in unstructured environments

How is trajectory planning normally carried out in off-road/unstructured environments? In particular I'm interested in how stereo vision can be used to plot trajectories over obstacles - for example, ...
FourierFlux's user avatar
1 vote
1 answer
72 views

My Pick and Place Program Not Working

hope you are all well. I am trying to finish a capstone project on Coursera. It asks me to carry a cube object from an initial position to goal. This video shows the movement. Project website: http://...
kucar's user avatar
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1 vote
1 answer
269 views

Compute orientation velocities 6-DOF robot

I am trying to compute the joint velocities a 6-DOF manipulator(a typical industrial robot). I have an initial position [xi, yi, zi, T1i, T2i, T3i] and goal position [xf, yf, zf, T1f, T2f, T3f] in the ...
Lucas's user avatar
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1 answer
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What is a cost and cost function in path planning?

Surfing through websites and videos, I interpreted that cost refers to parameters such as time taken to go from start position to the goal position or distance traveled in every possible path and cost ...
Tejal Barnwal's user avatar
2 votes
2 answers
825 views

SLERP velocity and acceleration (3d Orientation interpolation)

Hey guys I am quite new to quaternions and I am a bit unsure as to how to use them. How are the velocities and accelerations trajectories determined using quaternions? I have been using slerp to ...
Spaceman's user avatar
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1 answer
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how do I decide what is the order of the polynomial I need to use in a polynomial iterpolation for a trajectory?

I am a student studying robotics, and I am focusing on trajectory planning for a robotic arm. In particular, I am studying polynomial interpolation for defining the trajectories, and I am having some ...
J.D.'s user avatar
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1 vote
1 answer
98 views

How do I find the minimum time for computing a trajecotry for a robotic arm?

I am studying robotics and I am focusing on trajectory planning. I have been struggling with this topic for a while, and I still have some doubts that I cannot solve. One of them is the following: I ...
J.D.'s user avatar
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1 vote
1 answer
114 views

Reset coordinate system of robot while maintaining relationship to the previous

I am currently estimating a robot's pose (3d position and rotation matrix) with an IMU and I want to reset the localizer in the middle of the run while keeping the relationship to the pose it had when ...
Damuno's user avatar
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3 votes
1 answer
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where can I find a good source to study robotics kinematics and trajectory planning relative to robotic arm manipulator?

I am a student, and I have to study for a Robotics exam which consistes mainly in kinematics for a robotic manipulator and trajectory planning also for a robotic manipulator. In the part relative to ...
J.D.'s user avatar
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0 votes
1 answer
317 views

Going from Spline to Differential Drive Command

I have a differential drive robot that needs to move along a path stored in its memory as a spline. I am currently trying to understand the mathematics of determining how much power to apply to each ...
Andrew Carluccio's user avatar
3 votes
2 answers
398 views

Why in trajectory planning in joint space the manipulator never crosses a singularity?

I am studying robotics kinematics and I have studied that if we plan a trajectory in joint space it is impossible for the robot manipulator to cross a singularity during its motion, while in cartesian ...
J.D.'s user avatar
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2 votes
0 answers
54 views

Trajectory tolerance limits

I have a trajectory planner, which calculates the trajectory assuming that the robot is following the planned trajectory. From sensors I get the position of the robot, which has an offset from the ...
nionios's user avatar
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1 vote
1 answer
2k views

What are the differences between trajectory planning, trajectory tracking, path planning, path following and motion planning?

What are the differences between trajectory planning, trajectory tracking, path planning, path following and motion planning? And what are the basic methods they use?
winston's user avatar
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1 vote
2 answers
221 views

Iterative calculation of trajectory

In the answer https://robotics.stackexchange.com/a/7512/22953 there is an example for trapetzoid trajectory planning that results in the following table. \begin{array} {|r|r|} \hline time &...
Pibben's user avatar
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2 votes
1 answer
130 views

Given an initial position, a goal position and a duration find a trajectory

I have an initial position $X^R_{init}$ of the robot ($x$, $y$ and yaw) and a goal position $X^R_{goal}$ I need to create a trajectory of duration $T$ with $n$ waypoints to move the robot from its ...
Phrixus's user avatar
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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 ...
Chanoh Park's user avatar
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