Questions tagged [kinematics]
The kinematics tag has no usage guidance.
54
questions
2
votes
2answers
67 views
Degrees of Freedom for Complex Pulley Systems
I'm trying to understand DOF clearly, but this pulley system has me doubting myself. When I try to determine the degrees of freedom, I sum the DOF of each object, and subtract the constraints. for ...
0
votes
1answer
34 views
In circular motion , why do we say this is centripetal acceleration
Let us say a particle is moving in a circle with Uniform circular motion .
Then , if I take an equation like this .
$\theta$ = S(Arc length or Total distance covered ) / Radius of circle *( time ...
0
votes
2answers
35 views
Did not understand this regarding angular velocity
It says $V\sin \alpha$ (component of velocity perpendicular to OP) is the cause of angular displacement. How is it?
if only $V\cos \alpha$ existed, we need not turn over head to always to look at a ...
2
votes
1answer
33 views
Gear Ratio of a Stepped Planetary Gearset
I was looking into planetary gearsets, and came upon the concept of a stepped planetary gearset. In the image shown above, if my input was the blue sun gear, the output was the planet gear, and the ...
0
votes
0answers
9 views
3DOF end effector control
I have created a simple serial robot with some servos and CAD.
Each joint has 180 degrees of freedom, where they all have 180 degrees of freedom.
I haven't specified where the 180 degrees of freedom ...
1
vote
1answer
24 views
differential drive vehicle in screen coords
differential drive vehicle in world frame
what would change in the kinematic model of the differential drive vehicle if i wanted to simulate it
using pygame module in python ( pygame or opencv or any ...
2
votes
0answers
25 views
Problem in the inverse kinematic model of a car like vehicle?
I'm a electrical engineering student and i am building a simulation of a car like vehicle .
As I understand it:
The input for the forward kinematic model are the control
variables and the output is ...
0
votes
2answers
56 views
What does it mean for a machine design to be “kinematic”?
I've seen the term "kinematic" used qualitatively to describe machines several times in books and on YouTube. I think I understand what kinematics is as a study, but I'm not sure what people ...
-1
votes
1answer
32 views
Stewart platform 6DOF parrallel manipulator static force diagram
I am trying to develop a statics free body diagram of a stewart platform 6dof parallel manipulator motion table. I have the base points (B1,B2,B3,B4,B5,B6) and the top platform points (P1,P2,P3,P4,P5,...
4
votes
2answers
90 views
What do I need to operate this motor?
I am currently designing a tennis ball launcher. I am looking to use the friction wheel approach, where you have the ball passing through 2 spinning wheels and being launched by the frictional force. ...
-1
votes
1answer
29 views
Euler rotations and acceleration
I have a system determined by 3 Euler angles that describe the orientation with respect to a fixed coordinate system XYZ.
The angular velocioties are: $\omega_2$ (precession), $\omega_1$ (nutation) ...
2
votes
0answers
24 views
How to measure / calculate Tait-Bryan angles of a moving platform in SimMechanics
I exported a model of the mechanism created in SolidWorks to SimMechanics in order to explore the possibilities of control. To solve the problem, i need to know the angular position of the mobile ...
-3
votes
1answer
36 views
Maximum velocity of an athlete [closed]
I was solving a mechanics sum
An athlete running a 100m run starts from rest and reaches the maximum speed in a distance of 15 m. He runs the remaining distance with that velocity and reaches the ...
1
vote
1answer
18 views
Purpose of normalization of Jacobian in a parallel manipulator
I am currently studying a robotics paper, where a normalized frobenius norm of a matrix is calculated as part of determining the condition number of the corresponding linear system of equation:
$\...
1
vote
1answer
33 views
I have the yaw rate, rear wheel speeds, and the radius of tires, how to find x and y speeds?
I only have these 3 data sets:
rear right and left wheel speeds (they change with time)
yaw rate (also changes with time)
constant dynamic rolling radius
How am I supposed to find the directional ...
2
votes
1answer
93 views
Center of rotation (rigid body)
I know the meaning of (instantaneous) “center of rotation” and “center of zero acceleration” for a rigid body. I know that they do not coincide (in general) and that their positions change with the ...
1
vote
1answer
83 views
How to compute the size of a polygon moving along non-circular guide rails
I am trying to compute the optimal (a non-optimal solution would also work) size of carts that can move along guiding rails. Each cart is connected to the rails at two points. Each cart is also ...
3
votes
1answer
51 views
How do I call a kinematic assembly that converts rotary motion to sawtooth linear?
I have in mind a device somewhere in between a firearms trigger and a clock escapement. One way it could be constructed is as follows:
A crank would displace a linearly moving slider backwards, so ...
1
vote
1answer
698 views
What are displacement field and Deformation field?
I am studying mechanics of materials while I came across these terms called the displacement fields and the deformation fields. I am not able to understand the difference between them. Can someone ...
0
votes
1answer
190 views
Designing cylindrical cam
So I need to design a cylindrical cam (aka barrel cam I think). I'm an aerospace engineer so I've never had a course on cams/gear design (wish I had though). Is there a general equation for the curve (...
0
votes
1answer
109 views
Moment of Inertia of a Rotor System
I need to settle a discussion on the following question:
Part A:
Find the equivalent spring constant for springs in series
Use equations of motion, sum of torques to find natural frequency of the ...
1
vote
1answer
42 views
Torque computation for different attachment point
I have a pretty basic question but I would like to be sure of what I think.
I have a setup like the one in the figure. I have two motors which can generate two forces $F_1$ and $F_2$ perpendicular ...
2
votes
1answer
99 views
Dynamics of a rigid body in a system of two linear drives
I've been trying to solve the dynamics of this system for quite a while, but cannot seem to get the right answer. I've tried solving it with Lagrangian method but I am not so confident with the ...
0
votes
1answer
494 views
Deriving the equations of motion for free-floating spacecraft with a single link robot arm
Note: I had previously posted this question on the Space and Robotics SE sites, but received little/no response. So I've deleted the previous posts and repasted my question here in the hope of ...
-1
votes
1answer
262 views
Inertia relief in ANSYS - rotating model
I'm trying to use ANSYS to solve statically a dynamic problem.
As shown in the image below, there is an orange bar that is constraint to slide horizontally only and attached to another bar (pink) ...
3
votes
0answers
1k views
How to calculate the coupler length in a crank rocker mechanism
I'm trying to learn a bit about building kinematic mechanisms by building a small project. The goal is to be able to open and close a box programmatically via a servo motor.
I have a small box that ...
3
votes
1answer
361 views
4 Gears in a Circular Pattern - Calculating the Proper Distances for Meshing
I have recently been working on a gearbox for a robot. I have this pattern of 4 gears with each gear connected to its 2 neighbors. It looks like this:
You will probably notice something though. ...
1
vote
1answer
105 views
Bending Moment Doubt
I don't understand how bending moment is being calculated in the problem mentioned in the above link. I understand the parts after that i.e. calculating elastic potential and partial derivatives but I ...
0
votes
2answers
2k views
What is meant by “shock load” in gears?
What is meant by shock load in gears?
What are steady, light, medium and heavy shock loads?
0
votes
0answers
47 views
No. Of Instantaneous centres
I’m reading “Theory of Machines and Mechanisms” by Joseph Shigley.
Page No. 118 - The author states that A mechanism has as many instant centres as there are ways of pairing the link numbers. Thus,...
2
votes
0answers
52 views
Rotating four cylinders with one motor/actuator
I have a setup with 4 cylinders placed next to each other in following configuration. The cylinders are made of .2mm stainless steel. I would ideally want to rotate them along their axis using a ...
1
vote
1answer
73 views
Unachievable motions because of singular Jacobian
This is the Jacobian of a robot arm (IBB IRB 120) with already specified joint angles (0,0,0,0,0,0). This Jacobian is singular for this configuration.
...
1
vote
0answers
316 views
Inverse kinematics solutions pros and cons
I know at least 3 different approaches to solve inverse kinematics problem. They are pseudo inverse jacobian, cyclic coordinate descent and ANFIS networks. I would like to know advantages and ...
1
vote
3answers
150 views
Compound gear system: Finding velocity
In the figure below we have that the gear $A$ is has an fixed axis and has the radius of $R_a = 0,1m$ and, in the instant represented in the figure spins clock-wise with angular velocity $\omega_a = 4\...
3
votes
2answers
183 views
Rotational Motion Kinematics - Not sure how to fix axis of rotation
Hi I am trying to make a CAD model of something like the scoop sampler shown below.
http://www.rolls-royce.com/~/media/Files/R/Rolls-Royce/documents/customers/nuclear/scoop-sampling-tcm92-50918.pdf
...
2
votes
0answers
912 views
Forward and Inverse Kinematics of PUMA 560
I am currently coding a Forward and Inverse Kinematics solver for a PUMA 560 robot. For the Inverse Kinematics part I am using the closed for solution given in this paper. But my issue is, my solution ...
1
vote
0answers
95 views
force transmission in kinematic chain
In the following kinematic chain, I would like to get equation to go from
$F_{in}$ to $T_{out}$.
(excuse the poor drawing, nodes 3,4,5 are always aligned)
Here's my attempt :
The torque at $1$ is : $...
3
votes
2answers
214 views
Universal joint vs Double Universal Joint (CV configuration) kinematics
Concerning this subject, I consulted the following Wikipedia page: Universal joint
where the elementary kinematics equation of the U-joint is stated.
But, a little bit further in the article Double ...
0
votes
1answer
169 views
Kinematics Mechanics Find the length of the belt and the speed of the rack
For A. I know that the formula for belt is simply
$L=\frac{Pi(D_a+D_b)}{2}+2C+\frac{(D_b-D_a)^2}{4C}$
Which gives me $L= 116.99"$ since C is equal to $50$
For B. However I'm stuck and can't get the ...
3
votes
0answers
37 views
Parameter effects on kinetics of esterification for bio-diesel production
I want to discuss the effect of parameters on the kinetics of esterification for bio-diesel production. In esterification process, temperature effect and molar ration are two important parameters. ...
2
votes
1answer
936 views
Deformation gradient, strain tensor from cylindrical coordinates
I do not have any engineering background but I am studying some mathematics to try and understand and solve this problem. I have a mesh (M1) in cylindrical coordinates and this deforms into a mesh (M2)...
3
votes
2answers
166 views
Questions on machinery terminology
I have some questions in the basics of machinery terminology
Can a spring ever be a link? Most books (eg. Ham et al. 58, Shigley pg. 5) consider links to be rigid. However, I have come across ...
2
votes
2answers
144 views
How to interpete the formula: $I_{G}\alpha = \dot{\vec{H}}$?
I am having hard time to fully undestand what those formula's actually mean. I know the meaning of each element:
I : moment of inertia
H : angular momentum
$\alpha$: angular acceleration
$\omega$: ...
5
votes
2answers
9k views
Calculating torque needed to climb a graded hill
I've been designing an electric skateboard which is driven by only one of the rear wheels (for the moment). As I was picking out motors for the board, I soon realized I would need to find a balance ...
5
votes
2answers
430 views
How to calculate the velocity of a piston-like linkage?
I ve tried to solve this problem in so many ways but still didn't manage to do it...
What would be the correct way to solve it please?
This arm of this mechanism has a length of 0,2m. The piston has ...
3
votes
1answer
100 views
Why do 2 points on a mechanism not have the same angular velocities?
Could someone please explain me why the velocity of point P and P' aren't the same? Appearently it is because the angular velocity of point A and B aren't the same.
We are only given that the angular ...
2
votes
2answers
5k views
How do you find the kinematic degrees of freedom of a mechanism?
In the above mechanism it is required to find the generalized coordinates to write equation of motion of the MDOF system. I just want to ask how do we actually approach such a problem? How to identify ...
6
votes
2answers
3k views
Feedback control of two-link planar manipulator
TL;DR: how can I calculate the disturbance at each joint due to coupling forces in a two-link planar robot manipulator actuated by two independent DC motors?
I'm studying control theory and trying to ...
1
vote
0answers
113 views
How can a piece of steel rotated without any power input? [closed]
Currently I am trying to rotate a piece of steel >90 degrees without any power input. The piece of steel is attached on the wall. A servo is also attached on the steel.
This question addresses ...
1
vote
1answer
636 views
What are the basic mechanism, components or parts to generate relative movements?
I'm an engineer in industrial design and despite that I studied mechanics, kinematics and dynamics, I got difficulties when I try to label or find components which could enable my designs have ...
