Questions tagged [kinematics]

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

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How to make one robot follow the other in parallel formation

This is quite a basic question. I'm practising robot programming with VRep. I have 2 K3 robots in the scene. One robot follows a predefined path. I want the second robot to move "in parallel" with the ...
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3 votes
3 answers
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jacobian of Abb irb140 robot

Can someone please help me with the jacobian matrix equations for Abb irb140 robot. Or an easy way by which I can derive it given the DH parameters. I need it to implement some form of control that am ...
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2 answers
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What are the advantages of using the Denavit-Hartenberg representation?

When one wants to model a kinematic chain and in particular define the frames attached to each body, it is common to use the Denavit-Hartenberg parameters. What are the advantages of this ...
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2 votes
2 answers
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How does one calculate the angular motion of each node in a robotic arm

A robotic usually consists of joints with sections of possibly varying width connected together. Considering we know how much each is bent and the length of each section, and their location in 3D ...
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2 answers
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What is a suitable model for four-wheeled differential drive rigid-body robots?

I found a model for 2-wheeled robots here: What is a suitable model for two-wheeled robots? How should I adapt it to a 4-wheeled setting?
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Denavit–Hartenberg parameters of a robot with spherical wrist

What are valid values for the Denavit-Hartenberg parameters $d$ and $a$ (sometimes called $r$) of the last 3 links of a robot with spherical wrist? From this reference, "A spherical joint can be ...
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1 answer
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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 ...
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3 votes
1 answer
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Forward Kinematics Two fixed standard wheels

What would the equations be for the robot's angular and linear velocity at P and also P2? I think I'm doing it wrong... WL = left wheels angular velocity WR = right wheels angular velocity For P I ...
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8 votes
3 answers
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Is configuration space same as joint space?

For robotic manipulator like the one on the picture: are the configuration space and joint space equivalent? I am trying to understand difference between the two...
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6 votes
2 answers
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How much accuracy could I get position tracking with a 3-axis accelerometer and gyro sensor, and compass, and how would I do it?

Given a 12' x 12' field (4m x 4m), a reasonably cheap 3-axis gyro sensor and accelerometer, and compass, I plan to design a device capable of tracking its position to sub-centimeter accuracy for a ...
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4 votes
3 answers
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Algebraic and geometric in inverse kinematic

I'm just wondering that is there any case that when algebraic way can't solve the problem while the geometric can ? Cause I'm working on a 2DOF robotics arm This one, I know the length of L1 and L2, ...
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Turning a differential drive robot to a specific angle [duplicate]

Given a robot with 2 wheels with radius r on one axle with length D, I want to set the wheel speed so that it turns to an angle phi as fast as possible. The timestep t is 64 milliseconds. I thought ...
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4 votes
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Defining frames for 5DOF robotics arm

For examples if i have this robotic arm: Example, for the base rotation (5th DOF in the clip at 0:58), we know that the Z axis for that joint will be the same as the Z axis for the base frame{0}, but ...
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How to calculate the right and left speed for a tank-like rover?

I am trying to control the Rover 5 robot using an Android app with a touch-based joystick control in the app UI. I want to calculate the speed of the left and right motors in the rover when joystick ...
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3 votes
1 answer
293 views

Performing the proper coordinate system transformation

I could use some guidance regarding a coordinate system transform problem. My situation is this: my system begins at some unknown location, which I initialize the location (x y) and orientation (roll, ...
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How to correctly compute direct kinematics for a delta robot?

I'm trying to put together a simple simulation for a delta robot and I'd like to use forward kinematics (direct kinematics) to compute the end effector's position in space by passing 3 angles. I've ...
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12 votes
2 answers
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Smooth servo movement for a crawling robot

I made a small crawler robot a little while ago that had two legs with two degrees of freedom each, so 4 RC servos total. While I was programming the movement of the legs I noticed that they moved ...
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15 votes
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Calculate position of differential drive robot

How do you calculate or update the position of a differential drive robot with incremental sensors? There is one incremental sensor attatched to each of the two differential wheels. Both sensors ...
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1 vote
1 answer
539 views

How to control velocity ratio when turning angle is θ?

Im designing a differential steering mechanism for my robot. Supposing my robot is going in a straight line and I want it to change it direction by a certain angle( $θ$ in the diagram). What should ...
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  • 143
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How to design a differential steering mechanism?

I want to give my robot a differential mechanism for the system of turning and steering. Considering the case of turning a right-angled corner, the robot will achieve this by following a gradual ...
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  • 143
6 votes
2 answers
338 views

Drone targeting

Imagine a "drone" and a target point on a 2d plane. Assuming the target is stationary, there are eight parameters: ...
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7 votes
1 answer
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Numpy alternatives for linear algebra and kinematics in python?

Are there any decent python numerical package libraries besides numpy for python? Numpy relies on gfortan which itself must be compiled correctly for your platform to avoid hidden/insidious numerical ...
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6 votes
2 answers
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Assigning Frames and Deriving Link Parameters

The textbook I'm using doesn't have the answers to the practice questions, so I'm not sure how I'm doing. Are the following DH parameters correct given the frames I assigned? The original question is ...
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4 votes
2 answers
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How to invert D-H parameters

I currently have a working kinematic chain made by a set of ten links in D-H convention (with usual parameters [ $A_i, D_i, \alpha_i, \theta_i$]). But my task currently requires the inversion of some ...
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10 votes
1 answer
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How do I convert link parameters and angles (in kinematics) into transformation matrices in programming logic?

I'm doing robotics research as an undergraduate, and I understand the conceptual math for the most part; however, when it comes to actually implementing code to calculate the forward kinematics for my ...
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7 votes
2 answers
312 views

Is there a tool for building and analysing robots (kinematics, control) visually?

I am reading research papers about robotics and many of them follow the same pattern: some construction is established kinematical formulas are read from the mechanical structure the state space is ...
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  • 359
12 votes
2 answers
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Differences between Ackermann steering and standard bi/tricycles concerning kinematics?

I got the following homework question: What are the general differences between robots with Ackermann steering and standard bicycles or tricycles concerning the kinematics? But, I don't see what ...
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19 votes
4 answers
25k views

Computing the Jacobian matrix for Inverse Kinematics

When computing the Jacobian matrix for solving an Inverse Kinematic analytically, I read from many places that I could use this formula to create each of the columns of a joint in the Jacobian matrix: ...
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11 votes
3 answers
3k views

With a 6-axis robot, given end-effector position and range of orientations, how to find optimal joint values

Given a six-axis articulated robot arm holding a tool at its end-effector, if I have a desired tool position and tool orientation, there will be exactly 1 solution to the inverse kinematics equation ...
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  • 369
21 votes
3 answers
14k views

How can the inverse kinematics problem be solved?

The forward kinematics of a robot arm can be solved easily. We can represent each joint using Denavit–Hartenberg transformation matrices. For example, if the $i^{th}$ joint is a linear actuator, it ...
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