# Questions tagged [kinematics]

Kinematics is the branch of mechanics dealing with the motion of points and objects.

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### Forward kinematics confusing point

I am studying robot arm kinematics. In order to construct a transformation from a global coordinate frame to the end effector frame, I have seen references to the Denavit–Hartenberg (DH) convention. ...
1k views

### Finding correct RPY for approaching a known point on a plane

I have a robot with 6 DOF that I want to use to grab a hanging sheet at a specific point near its edge. The grip needs to be perpendicular to the edge and co-planar with the point of course. I have ...
118 views

### From a linear force actuator that spans multiple links and joints to the equivalent motor torque

I am programming/using a rigid body joint-space dynamics solver for robots in which I want to implement linear force actuators between links with their equivalent torque sources that are 'spanned' by ...
91 views

### How to find angular velocity using pure pursuit algorithm?

I have implemented the pure pursuit algorithm for my differential wheeled robot as described in the following paper: http://www.enseignement.polytechnique.fr/profs/informatique/Eric.Goubault/MRIS/...
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### Difference between Denavit-Hartenberg and Rodrigues formulas/conventions

I am trying to compute the forward kinematics for a 6 DOF robot arm. I've found two methods : the Denavit-Hartenberg (original and modified) and the product of exponentials with the Rodrigues formula. ...
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### DH table which link refers to which joint

I'm assigning frames to my kinematic model but I'm having a hard time understanding which frame each link refers to. I labeled each of my joints with Train/Tilt/Pan/Roll and I want to match those up ...
42 views

### Multiple Rotations via Matrix Multiplication

so I am having an issue understanding why you right multiply for current frame rotation vs left multiply for fixed frame. Let us say you want to: Rotate about x, then Rotate about current y, then ...
42 views

### Finding torque equation for my robotic arm

I am designing a 5 dof robotic arm, and for that I would like to find a torque equation. However, I am a little confused here: According to me the torque equation for M1 should be l2m2+l3m3+l4m4+l5m5 (...
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### Deduce all possible configuration for a given CONF param FANUC

I am working on the "CONF" parameter of FANUC Robots. The "CONF" param determine the pose of the robot (maybe to have only one inverse kinematics solution). This configuration is ...
41 views

### Parallel spatial mechanism - DOF

The parallel mechanism is composed of a moving platform and a base (or frame) connected by four legs. Each leg is composed of five revolute joints numbered 1, 2, … 5 from the base to the moving ...
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### Ground based path generation from RGBD camera

How does one generate a trajectory for a ground vehicle using an RGBD camera? For a drone it's simpler since you're not constrained by having to move on the ground but it's not clear to me how ...
38 views

### How can I find a robot's distance from an object given FOV, bounding box measure, and image width and height in pixels?

The robot is standing in the middle of the arena. I am confused on how to convert the pixels into a real life distance and how to use the bounding box. Starting help is appreciated.
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### How to do a relative rotation of a cuboid such that the longest edge is upright?

I am using pybullet. I have a cuboid with half extents [4,2,1] corresponding to x,y,z dimensions. I rotate this cuboid around the z world axis theta and also translate it by [0, 0, .65]. I take a ...
63 views

### Degree of maneuverability mobile robot

According to the traditional kinematic theory for mobile robots  a mobile robot with a steerable wheel and two passive casters presents a $\delta_m=2,\delta_s=1,\delta_M=3$. This is easy to ...
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### Jacobian Derivative (Analytical?)

If I understand this correctly, given the Jacobian Derivative $\dot{J}(q)$ derived using the method presented from the paper by (Rhee, J. Y., & Lee, B., 2017) where the algorithm summarized ...
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### Link collision avoidance for redundant manipulator

I am trying to have my robot arm follow a trajectory while avoiding collisions between obstacles and the robot links. The way I go about it is to find the closest point on the robot arm, and treat the ...
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### Can someone help me understanding reference frames in OxTS data in KITTI Vision Benchmark dataset?

If anyone has worked with KITTI dataset, can you explain the reference frame used in roll pitch yaw values? I downloaded the raw data from this link: http://www.cvlibs.net/datasets/kitti/raw_data.php ...
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### Formulas for calculating the passive joints angular velocities

We have the following parallel robot architecture: Positions of the vectors $u_i, v_i, w_i$, the angles $\theta_i$, angular velocity $\dot{\theta_i}$ and the Jacobian $J$, that mapping vector of ...
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### Find the kinematic parameters using DH by Craig convention

I am trying to find the kinametic parameters using the J. Craig of the DH parameters for the following 2-DOF robotic manipulator. where $\ x,y$ are the axes of the reference frame and $\ q_1 , q_2$...
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### About kineto-statics duality of the closed chain

I can't understand the content from the book "Robotics Modelling, Planning and Control", page 151. Suppose that there is a manipulator which has a closed chain. And Let $\textbf{q}_a$ actuated joint ...
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### Task Space Control Parameters for 6-Dof Manipulator

I'm developing a Task Space controller based on speed for a Universal Robot 5. I've already calculated the Jacobian, position and rotation error for the classic control method: The method works fine ...
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### how to normalize PWM if the value exceeds the maximum speed limit

I have implemented inverse kinematics for nonholonomic mobile wheeled robots, and the RPM range of the motor that I used is -50 to 50, while for PWM is from 1300 to 1700. But in certain cases, the RPM ...
90 views

### Algorithm for orientation (pan/tilt) towards a moving point

Main Question: note: The code in this question is pseudo-code, I'm using Python, but my pseudo-code is a mix of Python and C++. I have a camera on the top of my robot's "head" which has pan and tilt ...
263 views

### Treatment of euler angles in quadcopter control

In most implementations of quadcopter control systems I've seen, each axis of the quadcopter is controlled independently. For example, to control the rate in the roll axis, the desired output is ...
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### Inverse kinematics for a robot lamp

I've been working on a robot lamp. Looking something like this: So i had a few questions. I've decided to simplify the movements by giving the head a fixed orientation like you see in the picture. ...
42 views

### How to determine the angles between a UAV and a sphere

I have an UAV modeled in three dimensions with let's say position coordinates $p_{uav} = (x_1,y_1,z_1)$ that is moving in a direction $d = (d_x,d_y,d_z)$ and a moving obstacle modeled as a sphere with ...
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### Can active sensor data be fed into an Autodesk Inventor Simulation?

I'd like to drive the position of various components within a virtual assembly based on sensor data being collected in real time from an external device. Does Inventor support such a setup? The goal ...
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### IK Jacobian is always a singular matrix

I am trying to solve an inverse kinematics equation for 6DOF system, 3 rotation and 3 prismatic joints. I am trying to solve using perturbation method, by adjusting each joint and calculating the ...
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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 ...
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### can anyone explain detailly this video(title: sensorless active complaince)

https://www.youtube.com/watch?v=g8Je93soOZE i am interseted in how they achieve compilance and detect collision in servo without the use of sensors. so any one please explain briefly
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### How do you end up with 1 degree of freedom with one big link connecting 3 other links?

I was reading Modern Robotics by Kevin Lynch et al. and this robot was presented. They had introduced Grubler's formula which assumes independent joint which gives $dof = 0$ but this is not the case ...
74 views

### Orientation Problem of a 4-DOF manipulator

As shown in figure, I have a 4-DOF manipulator. I want to control the robot such that the end-effector should always be pointing down no matter where the robot is in the end space. For the ...
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### how to find the kinematic and dynamic model of the mechanism

enter image description here 5 links 4 revolute joints find the kinematic and dynamic model ,link 3 should be horizontal with ground and one end of link 1 and 5 there are sliders enter image ...
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### Looking for a course (online?) RE: systems with XY stages

Using XY stages is common in many fields: 3D printing Genetics instruments semiconductor lithography automated microscope slide imaging See for example https://www.asml.com/en/technology/lithography-...
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### inverse kinematics robot RRR

I realized an analisis of inverse Kinematics but I couldnt solver the equations that I find. the robot is RRR I believe that this problem have solution however I didnt find in the web :( if somebody ...
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### velocity and acceleration of end effector

assume we have maximum angular velocity and maximum angular velocity for each joint in 6 DOF manipulator. now how can we calculate maximum velocity and acceleration of end effector at any path planing?...
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### 6DOF kinematic robotic arm programm

I am trying to find a well documented library which I can use for my 6dof robotic arm (https://www.thingiverse.com/thing:1693444) But I cant find anything :( Does anyone have a python/c code for ...
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### How to Calculate Individual Axis Commands Out of 5 Axes G-Code?

I am dealing with 5 axis CNC machining time prediction. I would like to ask the question with providing some background and mentioning the constraints which what I concluded from some of the ...
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### Path curvature in kinematic bicycle model

I'm trying to develop an understanding of the control law for longitudinal and lateral control for self driving cars. While doing so, I came across the kinematic bicycle model which is used to derive ...
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### What is the mathematical relation between phi1, phi2, phi3 and motor PWM values for 3 wheel omni drive robot?

My question is that I cannot deduce the relation between phi1, phi2, phi3 values of the omni robot (3 wheeled) and the motor's PWM values, since I'm planning on designing the robot to perform "go ...
125 views

### Simple inverse Kinematic algorithm

I was looking for a simple inverse Kinematic algorithm that doesn't depend on eigen(doesn't work on my machine + dependency conflict never fixed it) Most of the code out in the internet is way to ...
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### 5 bar linkage hand exoskeleton

I have a project to design a hand exoskeleton for hand rehabilitation. The problem is that i'm thinked I only need the linkage mechanism with multiple 4 bar linkages. But because of human fingers ...
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### How can we estimate reliable angular motion from a monocular camera?

While I am working on a project, a question comes to my mind; how can we estimate reliable angular motion from a monocular camera, just for a typical indoor environment within a few seconds? So to ...
28 views

### How can I find the kinematics 2 differential drives attached together along their axes?

I have a system like shown in the diagram where 2 robots having differential drive are physically constrained together. Traditionally for a single robot, we find the Instantaneous center of curvature (...
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### How to calculate potential enegy of manipulator?

I'm trying to obtain dynamics of a 4 DOF robot. Firstly, I calculated all Transformation matrices and Jacobians. While solving Lagrangian there is two main things one is kinetic energy and the other ...
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### Design optimization method using indices

There are several methods like manipulability and conditioning index for design optimization kinematics performance, but these methods rely on the singular values of the jacobian matrix. I described ...
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### From an end-effector trajectory to joints movements

let's assume that our robot consists of 3 degree-of-freedoms. In order to move the end-effector of this robot along a straight line, these 3 joints have moved as below: Now, if the desired end-...
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### What is my last rotation matrix for the last three angles when i have found the first three when doing inverse kinematics to a 6dof robot?

I am doing inverse kinematics for a 6dof robot. I have used the geometrical method to describe the angles from one to three. I have trouble doing the next part. I know I that I have found the ...