The 2024 Developer Survey results are live! See the results

# Questions tagged [trajectory]

The tag has no usage guidance.

53 questions
Filter by
Sorted by
Tagged with
735 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 ...
• 43
411 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 ...
• 479
143 views

### 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 ...
• 479
918 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 ...
• 344
300 views

### 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 ...
• 23
133 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 ...
• 165
117 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 ...
• 173
56 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 ...
• 311
1 vote
74 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://...
• 328
1 vote
115 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 ...
• 479
1 vote
237 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 &...
• 111
1 vote
69 views

### 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 ...
• 133
1 vote
117 views

### 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 ...
• 169
1 vote
47 views

### 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 ...
• 137
1 vote
154 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 ...
1 vote
314 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 ...
• 21
1 vote
120 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 ...
• 11
1 vote
3k 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?
• 123
1 vote
26 views

### 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 ...
• 137
1 vote
48 views

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 ...
• 147
1 vote
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 ...
• 111
94 views

### 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 ...
• 17
331 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 ...
• 121
137 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 $(x,y)$ ...
• 479
90 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, ...
• 393
1k views

### 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 ...
76 views

### 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, (...
1k views

### 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 ...
• 101
30 views

### 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 ...
47 views

### 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 ...
• 17
274 views

### 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 ...
• 137
190 views

### 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. ...
• 1
81 views

### 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 ...
59 views

### 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 ...
• 479
342 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 ...
8 views

### Add constraints to cubic or quintic polynomial for robot arm trajectory generation

I am planing path for a robotic arm. I am using cubic/quintic polynomials for trajectory generation. How can I add constraints to cubic or quintic polynomial such that the generated trajectory is ...
• 63
5 views

### Record itinerary of a robot with ros2 bag and replay it

I am trying to evaluate a slam algorithm and for that, I want to create several maps of my environment with the same itinerary of the robot. To do that I have tried: I recorded the topic /odom alone, ...
6 views

### How to do a continous trajectory in Staubli VAL 3

I am doing a trajectory passing from 6 points with these command in VAL 3: for m=0 to 6 step 1 movej(p_iman[m],tTool1,mNomSpeed) waitEndMove() endFor ...
70 views

### Comparison of trajectories from odometries

Is there a way in ROS2 to compare trajectories from odometry data? I'm using robot_localization to calculate various odometry outputs by incorporating GPS and IMU data. I have a bag file where I ...
50 views

### Why 4th degree polynomials aren't used for trajectory generation?

I'm building and programming a controller for a robotic manipulator. Currently I'm figuring out how to generate trajectories in joint space. I'm following Introduction to Robotics: Analysis, Control, ...
72 views

### Planned Path vs Actual Path for Real Robot

I would like to compare/visualize the planned path and actual path of an industrial robot. I am using Moveit2 and I can access planned trajectory via /display_planned_path topic which is moveit_msgs/...
50 views

### 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 ...
9 views

### 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/...
20 views

### 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. ...
52 views

### 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 ...
• 25
56 views

### 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. ...
42 views

### 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 ...
24 views

### 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 ...
• 3,347
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 ...