Questions tagged [kinematics]

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

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52 views

I found the matrices but can't find the inverse kinematics angles

I need to find inverse and forward kinematics of Mitsubishi RV-M2 as a homewrok. I found the forward kinematics part. But I got stuck in inverse kinematics. Teacher said we can think that wrist ...
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1answer
4k views

How to create Matlab Simulation for Kinematics of Differential Drive

I studied the forward and inverse Kinematics of the robot and got a clear understanding. I am in the progress of developing my matlab simulation for a two wheeled differential drive robot. The robot ...
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2answers
842 views

Derivative of a Jacobian matrix

I have an RRR planar robot: Its forward kinematics transform is: $$ {}^{0}T_3 = \\ \left[\begin{array}{cccc} \cos\!\left(\mathrm{\theta_1} + \mathrm{\theta_2} + \mathrm{\theta_3}\right) & - \sin\...
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1answer
704 views

What kinematic equations should I use for Kalman filter state propagation in IMU based quadcopter navigation?

I am working on implementing a Kalman filter for position and velocity estimation of a quadcopter using IMU and vision. First I am trying to use the IMU to get position and velocity. In a tutorial [1] ...
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2answers
75 views

What is the top speed of a four legged robot? [closed]

In Neal Stephenson's novel "Snow Crash", a robotic/cybernetic creature known as a "Rat Thing" looses its bounds and runs to rescue another character. The Rat Thing is portrayed at moving over 700 ...
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61 views

Is there any robot stability control equation that describes the relation between velocity of the robot and its orientation?

Let’s assume at time t a moving robot (e.g. PIONEER 3-DX) changes it’s steering angle by $25^{\circ}$. Obviously, in order to maintain stability and avoid overturning, the robot must reduce its ...
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3answers
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2DOF arm with quick movement: Stepper, servo, or DC motor?

To make a two degree of freedom arm capable of speeds needed to play air hockey, how should the arm be controlled? I'm wondering about speed vs accuracy. The following image is from a project ...
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4answers
858 views

Forward and Revers Kinematics For Modified Hanging Plotter

I'm building a modified version of the standard hanging plotter (v-plotter). The basic idea is that you have two cables hanging from stepper motors which form a triangle supporting the pen at the tip. ...
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1answer
173 views

Determining the graspable range of a robot arm

I have a 6 DOF robot arm, and I want to do some object grasping experiments. Here, the robot is rigidly mounted to a table, and the object is placed on a different adjacent table. The robot must pick ...
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1answer
354 views

Rostock Delta Robot 3D Printer Degrees of Freedom (DOF)

What is the degrees of freedom (DOF) of the Rostock delta robot 3d printer (delta mechanism that consists of three prismatic joints)? Here's the link to the delta mechanism I'm referring to: https://...
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13k views

Position Control vs Velocity Control vs Torque Control

Please can somebody explain to me the difference between Position Control, Velocity Control, and Torque Control? Specifically, I am thinking in terms of a robot arm. I understand that position control ...
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2answers
376 views

Distance calculation with two robots and two obstacles

I have a problem with two robots and two obstacles in a space. Each robot can communicate its measurements to the other and can measure angles and distances. The two obstacles in the environment are ...
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2answers
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I'm looking for hands-on experience with different types of leg and hip designs for walking robots [closed]

I'm looking to find out, How do human-like legs compare to chicken legs and four-leg systems. In terms of cost, performance, speed, strength and accuracy. I'm interested in things like speed, agility,...
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Solving Inverse Kinematics with Gradient Descent

I am trying to implement my own inverse kinematics solver for a robot arm. My solution is a standard iterative one, where at each step, I compute the Jacobian and the pseudo-inverse Jacobian, then ...
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3answers
861 views

Computing the Jacobian Matrix — chain rule?

I am learning about robot kinematics and the Jacobian matrix, and I'm trying to understand how to compute the Jacobian matrix given a kinematic chain, such as a robot arm. I understand the theory ...
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1answer
430 views

convert toolframe coordinate to world frame coordinates?

I am not sure how i should explain this, I am looking for a way to plot the trajectory an robot arm. An object is seen from the toolFrame frame, but how do I plot the position of each joint, such ...
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1answer
124 views

Mobile robot algorithm implementation error

I am working in reproducing a robotics paper, first simulating it in MATLAB in order to implement it to a real robot afterwards. The robot's model is: $$\dot{x}=V(t)cos\theta $$ $$\dot{y}=V(t)sin\...
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1answer
49 views

Principle of virtual force - General help in understanding / explanation

I'm an Electronics student taking a module in Robotics. From the example, I understand line 1 as the Jacobian is found from the time derivative of the kinematics equation and such relates joint ...
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0answers
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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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1answer
496 views

inverse kinematics for 6 jointed robots

I am a uncertain about how to compute the right homogeneous transformation matrix to compute an inverse kinematic Q-configuration. Looking at robot like this Where at the end of this robot I have ...
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2answers
191 views

Angle to a circle tangent line

I want to simulate the detection of a moving object by a unicycle type robot. The robot is modelled with position (x,y) and direction theta as the three states. The obstacle is represented as a circle ...
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2answers
1k views

Difference between an underactuated system, and a nonholonomic system

What's the difference between an underactuated system, and a nonholonomic system? I have read that "the car is a good example of a nonholonomic vehicle: it has only two controls, but its configuration ...
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1answer
449 views

Dynamic model of a robot lifted by a balloon (Multibody system)

I'm having a hard time trying to understand how to obtain the dynamic model for a system similar to the image. The balloon is a simple helium balloon, however the box is actually an aerial ...
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2answers
844 views

Finding rotation quaternion

I am trying to use a quaternions for robotics and there is one thing I don't understand about it. Most likely because I don't understand how to define position with quaternions and how to define ...
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1answer
319 views

Are operational space and joint space dependent on each other?

Some questions about this, my friends and I argued with this problem. Are operational space and joint space dependent on each other? I know that $x_e$ (end effector's pos.) and $q$ (joint var.) can ...
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1answer
205 views

List of books similar to Thrun's Probabilistic Robotics for robot mechanics and manipulation [closed]

What? Put together here a list of books (like the one for C/C++ on StackOverflow) that are spiritually similar to Sebastian Thrun's Probabilistic Robotics for robotic manipulation and mechanics. Why?...
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3answers
775 views

How many DOFs required to define a 3D pose

I understand that to be able to define point in 3D space, you need three degrees of freedom (DOFs). To additionally define an orientation in 3D space, you need 6 DOFs. This is intuitive to me when ...
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3answers
3k views

How to find kinematics of differential drive caster robot?

I'm working on a little project where I have to do some simulations on a small robot. I my case I'm using a differential-drive robot as one of the wheels of a bigger robot platform (which has two ...
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0answers
74 views

Accurate technique to locate position? [closed]

What is the most accurate way to locate the position and orientaion of the body during some motion (rotation and translation)? I need to track the body very precisely, the required accuracy is 100-...
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1answer
5k views

How to perform odometry on an arduino for a differential wheeled robot?

I am using a differential wheel robot for my project. I need to know the current coordinates of the robot with respect to it's initial position taken as the origin. I m doing the computation on an ...
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3answers
2k views

Forward kinematic computing the transformation matrix

I am the moment trying to compute the transformation matrix for robot arm, that is made of 2 joints (serial robot arm), with which I am having some issues. L = 3, L1 = L2 = 2, and q = ($q_1$,$q_2$,$...
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1answer
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DH parameters and Kinematic Decoupling

Is it possible to decouple a 5DOF manipulator? This question I asked earlier and I believe I got the right answers but I never show the drawings of the manipulator and now I'm hesitating during setup ...
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1answer
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Getting pitch, yaw and roll from Rotation Matrix in DH Parameter

I've calculated a DH Parameter matrix, and I know the top 3x3 matrix is the Rotation matrix. The DH Parameter matrix I'm using is as below, from https://en.wikipedia.org/wiki/Denavit%E2%80 Above is ...
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1answer
107 views

Relative orientation of two robots

Given two robot arms with TCP (Tool Center Point) coordinates in the world frame is: $X_1 = [1, 1, 1, \pi/2, \pi/2, -\pi/2]$ and $X_2 = [2, 1, 1, 0, -\pi/2, 0]$ The base of the robots is at: $...
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2answers
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Kinematic decoupling

Is kinematic decoupling of a 5DOF revolute serial manipulator also valid? The three last joints is a spherical joint. Most literatures only talks about decoupling of 6DOF manipulators. Thanks in ...
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2answers
11k views

Running my 3 DOF Inverse Kinematics Code: Works in MATLAB, not in Python

I asked a question similar to this earlier, but I believe I have a new problem. I've been working on figuring out the inverse kinematics given an x,y,z coordinate. I've adopted the Jacobian method, ...
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2answers
755 views

Robot arm reachability of a pose in Cartesian space

Given a set of robot joint angles (i.e. 7DoF) $\textbf{q} = [q_1, ... , q_n]$ one can calculate the resulting end-effector pose (denoted as $\textbf{x}_\text{EEF}$), using the foward kinematic map. ...
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1answer
729 views

Mobile Robot path reconstruction by using IMU acceleration and Yaw angle

I hope you can help me with my project. I'm using a skid-steering wheeled mobile robot for autonomous navigation and I'd like to find a way to be able to perform path reconstruction in Matlab. By ...
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1answer
2k views

How to use the Homogeneous transformation matrix?

I am trying to understand how to use, what it requires compute the homogenous transformation matrix. I know 2 points from 2 different frames, and 2 origins from their corresponding frames. I how ...
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1answer
2k views

How to convert between classic and modified DH parameters?

I currently have a description of my 22 joint robot in "classic" DH parameters. However, I would like the "modified" parameters. Is this conversion as simple as shifting the $a$ and $alpha$ columns ...
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1answer
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Hand Eye Calibration Solver [closed]

I have a rig for which I have a pretty good estimate of the static transformation between the camera and a joint based off of the CAD. It has some errors though and I was hoping to fix it by doing a ...
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2answers
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Why do we generally prefer DH parameters over other kinematic representations of robot arms?

I am specifically interested in DH parameters versus other representations in terms of kinematic calibration. The best (clearest) source of information I could find on kinematic calibration is in the ...
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3answers
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Mathematical Moddeling of Elastic Robots [closed]

We can easily compute the rigid robot kinematics and dynamics. There is many resources, simulators and modelling tools about it. But i couldnt find any of these for elastic robots. Can you suggest ...
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1answer
39 views

How can a memory alloy be used as an alternative to a compressor found in a refrigerator? [closed]

I'm curious about this alloy and how they say it can be used as an alternative to a traditional compressor. Can anyone explain how this would work? My goal is to understand that use case so I can ...
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4answers
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Assuming I have the angle with respect to two beacons, and know the distance between them, can I localize myself?

Let's assume I have the following situation, and need to find (x,y). Is it possible? There does not appear to be more than one solution to the system, but my trigonometry is a bit rusty. I feel ...
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1answer
297 views

Measuring angular displacement using the TI-SensorTag

I've looked around but can't find the answer, to what I hope is a simple question. I'm working with a TI-SensorTag, and I want to be able measure the rotation around the unit's Z-axis. Basically I ...
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6answers
4k views

How do I work out the kinematic solution of a robot arm?

I draw a robotic arm in Solidworks, but I'm not so sure about how to find out the DOF, forward and backward kinematic. Could anyone help me understand how to work out the kinematic solution of this ...
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4answers
219 views

Why I'm getting very long terms in the inertia matrix (or dynamics model) of the robot using matlab script?

I'm working on the dynamics model of a RRRR articulated robot, I'm following Euler-Lagrange approach and developing my code in m-file in matlab; I'm looking for dynamic model of this form: $$ D(q) \...
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2answers
2k views

How to find the body jacobain, for each link in a robot manipulator?

The links twist could be obtained, and thus The spatial manipulator Jacobian could be done, but when it comes to the body Jacobian, it is becomes difficult. Moreover, the adjoint transformation ...
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3answers
2k views

Jacobian-based trajectory following

I would like to control my 7 DOF robot arm to move along a Cartesian trajectory in the world frame. I can do this just fine for translation, but I am struggling on how to implement something similar ...