Questions tagged [kinematics]

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

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2answers
505 views

Using jacobian of arm robot to calculate transformation matrices?

I have been given a Jacobian for a 3 revolute joint robot. I need to obtain the origins of each of the joint. Origins of the joints can be obtained once I get $T^0_1$, $T^0_2$, $T^0_3$ and $T^0_4$. ...
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1answer
328 views

Optimization of link lengths for 3R serial manipulator

I am trying to formulate an optimization problem for determining link lengths of 3R manipulator shown in picture below, Following are the constraints, Robot arm should be reachable at point x = 100, ...
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2answers
630 views

How to check reachability of manipulator to a point?

I have written a MATLAB code for inverse kinematics of 3R robotic arm, which returns value of joint angles for given link lengths and end effector position and orientation. But if location of point is ...
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1answer
66 views

How can serial manipulator have unique condition number for given end effector position?

I am reading about Condition Number which is considered as measure of manipulability of robotic arm, it is defined as $$ k = \parallel J \parallel \parallel J^{-1} \parallel $$ Where, $$ \parallel J \...
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3answers
258 views

DH Parameters with offset base

I'm looking at a pan tilt (RR) system. I want to define the kinematics between a world frame and the end effector. Every example I've seen looks at the world frame as being at the first joint (the ...
2
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1answer
413 views

IMU measurement model

I read in this set of slides on p.11 that the IMU measurements, such as acceleration are affected by bias and noise, as expressed in this equation: $_B \mathbf {\tilde a} _{WB}(t) =\ \mathbf R_{BW}(...
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3answers
465 views

Confusion in fixing DH frames

I am analyzing a concept of a surgical robot with 4 revolute joints and one sliding joint. I am not able to fix the coordinate frame for last prismatic joint. Following are the schematics of robot and ...
3
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1answer
333 views

Extended Kalman Filter in robotics - Worth it?

I wonder if Extended Kalman Filter(EKF) is used in robotics, or is only Kalman Filter(KF) used in robotics. Kalman Filter is included in Linear Quadratic Gaussian(LQG) controllers. But how would EKF ...
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1answer
41 views

Electronic Spring Vibrating Spheres

For a science project, I'm looking for a way to actuate a spring, connecting two ~ 1 cm Styrofoam spheres to each other, at frequencies around 1-60 Hz. In other words, I want to be able vibrate 2 ...
2
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0answers
75 views

How do CAD programs solve for Inverse/Forward Kinematics problem in Assembly?

I am trying to solve for the Forward kinematics of a spatial parallel manipulator. Its loop closure (LC) equations are pretty long, and are being solved using numerical methods. As I am adding more ...
0
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1answer
72 views

clarity in understanding the moment of inertia matrix D and Coriolisis and centripetal matrix C as per attached equations

Would appreciate if anyone could help me understand the how if equation 6 and 7 are derived. Helping with any one D22 and C32 would suffice.
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1answer
72 views

How do the joint angles of a 4-legged impact the body's position with respect to the world frame?

For a four-legged robot (like Big Dog or the one shown here) how are the joint angles and "feet" position related to the body's frame in the world/inertial frame? For example, if I know the body's ...
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1answer
635 views

Understanding inverse kinematics with the Jacobian

I'm learning about inverse kinematics with Jacobians, and getting a little confused. So, let's say I have a robot arm with two joints with angles Y = (a, b) whose ...
3
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1answer
913 views

How rotate a point around an arbitrary line in 3D?

I have a body with origin at point A which is represented in homogeneous coordinate of matrix 4x4 and I would like to rotate it around an arbitrary vector in 3D space. I understand how to rotate the ...
0
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1answer
53 views

Calculate Transformation between two point sets - but with constrained Degrees of Freedom

How can I calculate the rigid-body transformation [R|t] between two 3d triangles, but restricted to a given N degrees of freedom (for N = 1..6) ? I know for N=6 I can get a least-squares solution via ...
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2answers
268 views

Localization within a map with gyro, accelerometer and magnetometer

My goal is to locate precision within a known map. If the size of the map is known, a rectangle 4 x 3 m, and I know the initial position and orientation of the robot, after a certain period of time ...
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4answers
220 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) \...
1
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1answer
61 views

I need help figuring out what motor is used in this design

I am learning how to make rigs for high speed motion control. Basically, whatever action needs to be executed must be done by a rig that is triggered at an exact moment. In this particular case, I ...
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1answer
405 views

Orocos KDL issue with Rotation (matrix) - Inverse Kinematics

I have a problem with the Orocos IK solver, especially with the KDL::Rotation matrix input. I try to call my KDL IK solver with a normal vector and a rotation. If I use the example values for the ...
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1answer
149 views

Does Inverse Kinematics need the current joint angles?

I had a discussion with a study colleague about the IK solver. The question was: Does IK need the current joint values to calculate the requested position. I think it doesn't need it. From my ...
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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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3answers
948 views

Confusion about order of homogeneous transform multiplication

This is my first post here, so if I unknowingly vioated any rules, mods are welcome to edit my post accordingly. Ok, so my problem is that following Craig's conventions, I can't seem to find the ...
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1answer
689 views

Real-time TCP position/pose control on a robotic arm such as YuMi: recommendation to calculate IK/Inverse Jacobian?

I plan to make a mouse or a gesture control robot like this video on YouTube : ABB Externally guided motion.  For a 6-axes robot, I could implement it by using ABB’s EGM (Externally Guided Motion) ...
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0answers
2k views

Any free or paid software for graphical drawing of Robotics Kinematic Scheme? [closed]

I have been searching for days looking for a dedicated software for easily draw kinematic diagrams of robotics like this: I came by this software but it is a bit hard to grasp. Is there any GUI based ...
4
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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 ...
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3answers
675 views

Forward kinematics equations

I'm stuck at computing forward kinematics equations. I have configuration of the first two joints like on the following image: Transformation from the origin to the first joint basis is trivial: ...
2
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1answer
97 views

How big is the set of kinematics singularities?

Suppose we have an $n$-DOF robot manipulator and let $q \in \mathbf{R}^n$ denotes a robot joint configuration. Then a singular configuration $q'$ is a configuration at which the Jacobian $J(q')$ does ...
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1answer
4k views

Matlab Inverse Kinematics 6 DOF

I'm trying to write an inverse kinematics Matlab code for a 6 DOF robotic arm that has the following link parameters: Twist angle (alpha): [-90, 0, 90, -90, 90, 0] ...
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0answers
79 views

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. ...
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1answer
253 views

How to Calculate the Translational and Rotational Velocity of a 4 Wheeled Robot?

I have a robot with a 4 wheel drive using mecanum wheels to allow for more mobility. For the engineering documentation I am looking to find both the translational velocity and rotational velocity of ...
6
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4answers
935 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. ...
2
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1answer
142 views

Integrating Forward Kinematics Map

Let the forward kinematics map be denoted by $\mathcal{F}$ such that $\mathcal{F}: \theta \in \mathbb{R}^{n} \rightarrow g \in SE3$ Let the minimal representation of $g$ be given by $x \in \mathbb{R}...
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1answer
214 views

Velocity Relation for Parallel Robots

In my course of "Advanced Robotics" with "Fundamental of Robotic Mechanical Systems" as the reference book I saw the following equation as the velocity relation for parallel manipulators such as the ...
2
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1answer
687 views

showing error while using inverse kinematics “ikine” for 4 dof robotic arm

I want to do forward dynamics but before that I got struck in inverse kinematics for 4 dof. My code is given below: ...
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1answer
58 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 ...
3
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1answer
744 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
76 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 ...
2
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2answers
990 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 ...
0
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1answer
62 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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1answer
7k views

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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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 ...
3
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1answer
108 views

Fit robot simulator to robot

I have odometry data $(x, y, angle)$ of a real two-wheeled robot, who received control commands $(forward speed, angular speed)$. Now I want to code a motion model (in C++ (/ROS)) which should follow ...
3
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1answer
181 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 ...
2
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2answers
192 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
100 views

Velocity derivatives using Quaternions [closed]

How to compute the angular and linear velocities Quaternions? I am new to this area and although I have studied the algebra I am unable to understand how to compute the velocities.
8
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1answer
2k views

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 ...
1
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1answer
367 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://...
3
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1answer
130 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\...
2
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2answers
421 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 ...
3
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2answers
99 views

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,...