Questions tagged [kinematics]

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

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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 ...
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2answers
389 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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455 views

Compensation for IMU mounting misalignment

I have an MPU6050 IMU and I would like to mount it on an FSAE car and use it to measure the yaw, pitch, roll, and angular velocities as it drives. As it's impossible to mount it perfectly flat and ...
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800 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 ...
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1answer
64 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
164 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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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 ...
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3answers
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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
4k views

How to create push and pull mechanism using Servo [closed]

How do I create a push and pull mechanism using a standard hobby servo? Eg. SG-5010 Preferably without the need of 3D printing.
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820 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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1answer
605 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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3answers
843 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: ...
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1answer
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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
102 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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55 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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0answers
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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. ...
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1answer
413 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 ...
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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 ...
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1answer
199 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
274 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 ...
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1answer
1k 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
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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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1answer
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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
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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
3k 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
938 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
77 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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1answer
67 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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6answers
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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
235 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
436 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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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
544 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
104 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,...
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2answers
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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
1k 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
700 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 ...
3
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1answer
142 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
56 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
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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1answer
725 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
202 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
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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
549 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
2k 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
474 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
313 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
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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
4k 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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