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Questions tagged [kinematics]

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

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1answer
179 views

One of the best ways to numerically integrate the velocity?

I need to get position $x$ from integrating velocity $v$. One could use 1st order Euler integration as $x_{t+1} = x_t + \delta * v_t.$ However, doing so leads to errors proportional to sampling time ...
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2answers
4k views

Inverse Kinematics of Parallel Manipulator (Delta Robot)

Let me start off by saying that I am currently going to university majoring in computer engineering. I love software/hardware and I especially love robotics and I want to apply my knowledge of ...
4
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1answer
1k views

Velocity Model Motion in Matlab (Probabilistic Robotics)

I want to implement the velocity motion model in Matlab. According to Probabilistic Robotics page 124, the model is as following \begin{align*} \hat{v} &= v + sample(\alpha_{1} v^{2} + \...
4
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1answer
156 views

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 ...
2
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3answers
3k views

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 ...
7
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2answers
3k views

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 ...
2
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2answers
190 views

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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2answers
999 views

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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1answer
3k views

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 ...
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 ...
2
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1answer
157 views

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 ...
6
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3answers
6k views

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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2answers
2k views

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 ...
3
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3answers
664 views

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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0answers
91 views

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 ...
4
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1answer
139 views

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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2answers
3k views

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 ...
3
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1answer
260 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, ...
3
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1answer
643 views

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 ...
10
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2answers
2k views

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 ...
14
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2answers
12k views

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 ...
1
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1answer
406 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 ...
3
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1answer
3k views

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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2answers
315 views

Drone targeting

Imagine a "drone" and a target point on a 2d plane. Assuming the target is stationary, there are eight parameters: ...
5
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1answer
721 views

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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2answers
1k views

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 ...
3
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2answers
517 views

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 ...
9
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1answer
2k views

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 ...
7
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2answers
262 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 ...
12
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2answers
3k views

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 ...
17
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2answers
20k 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: ...
9
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3answers
2k 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 ...
19
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4answers
9k 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 ...