Questions tagged [kinematics]

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

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Problem with Inverse Kinematics Solver (Jacobian Inverse Method)

I am trying to create an inverse kinematics solver for my 4-dof (all revolute joints) robot using the inverse Jacobian Method. However, it does not seem to be working as the distance between target ...
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Defining the specifications required by a 6DOF robot to impose a harmonic sinusoidal motion

Perhaps a bit of a simple question, but since I don't have a background in robotics/engineering, then I imagine this would be the perfect place to ask such a question. I am buying a 6-DOF Stewart ...
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control of a rod attached to a motor

I have a 76 cm, aluminum rod, attached to the shaft of a 12v DC banebot motor. The rod is hanging vertically initially, and rotates in the vertical plane. The task is to control the rod to make it ...
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Robot differential drive wheel speed

I would like to build a small robot. The robot will have 4 independent motors, one for each wheel. It will have a rear axle fixed and the front axle will be freely pivoting around its center, somewhat ...
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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 ...
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Holonomic constraints on an upright wheel

A wheel moving in free space has the six degrees of freedom of a rigid body. If we constrain it to be upright on a plane and to roll without slipping, how many holonomic and nonholonomic constraints ...
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In MuJoCo why do some XML files have objects fall to the ground while others are just fixed above the ground?

Why do some models, or objects in a MuJoCo XML script fall to the floor while others don't? In the models files that come with the MuJoCo zip, the robot arm (arm26) does not fall to the ground while ...
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I am trying to understand exactly what is happening when Gimbal lock occurs. I have read many explanations now which provide the high-level idea, in that Gimbal lock occurs when two axes are aligned ...
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Forward Kinematics for articulated manipulator not giving right answer

I calculated the forward kinematics for an articulated manipulator robot in ROS, but I am not getting the right answer. Here is the diagram for the robot configuration I used- When Q1,Q2,and Q3 are ...
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Trajectory following of 3-wheel omnidirectional robot

I created a three-wheeled omnidirectional robot on omni-wheels, there is also a program in which I can plot a trajectory when plotting a trajectory, such data are obtained (X, Y, Tangent X, Tangent Y, ...
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What does RR stand for in RR-manipulator?

I have memorized RR-manipulator as having 2 arms from Google images but "arm" isn't spelled with "R". I also noticed that RRR-manipulator has 3 links. Does R stand for revolute?
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How to calculate DH parameters for Higher Pair?

I am trying to build a robot which is having Bevel Gears connecting two links. I want to calculate DH parameters, but i am stuck with this bevel gear as when the joint rotates both angle and ...
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Calculate Torques & Forces From Jacobian Matrix

Dear Robotics Stack Exchange, I am trying to calculate the torques and forces for a 2DOF robot. I’m used the partial differentiation method to find the Jacobian matrix. I managed to find the ...
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How to find Joint Angles or Theta for 7DoF Robotic Arm

I am trying to find the joint angles or at least theta to be used to find the Denavit-Hartenberg Parameter for a robotic arm (Baxter's right arm). I have the link lengths and such, but I don't know ...
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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 ...
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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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Elegant way to mathematically relate joint positions (without a root/base joint) for easy re-rooting?

I'm pretty new to robotics, but have learned about the tranformation matrices and how to relate relationships between joints using transformation matrices. I just wonder if there is a system that ...
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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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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. ...
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Can a 6 DOF robot have multiple inverse kinematics solution with a constrained rotation/orientation

I trying to understand how manipulators robot works (6 DOF) I would like to know if the inverse kinematics (IK) solution give only one or multiple solution if we include the rotation (3x3 matrix) of ...