Questions tagged [kinematics]
The kinematics tag has no usage guidance.
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Complete classification of lower kinematic pairs
During research I keep seeing the statement saying that all possible lower kinematic pairs can be classified into one of 6 types, those being:
Revolute
Prismatic
Screw
Cylindric
Spheric
Planar
While ...
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30
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Are double universal (Cardan) joints exactly constant velocity?
Some double universal joints use a centering joint to ensure that the angle of the input and output are equal to maintain a constant velocity through the joint. From what I can tell, this centering ...
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How and why is kinematic control implemented?
First off, I apologize for what is likely a rather broad and formless question (and an even more broad and formless title). I'm a mathematician whose work sometimes carries him to control systems due ...
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Kinematic description of a gear rack moving around a cogwheel
I am facing some issues regarding the kinematic description of a gear mechanism (or maybe more accurately gear manufacturing process). Basically I would like to obtain an animation, where the cogwheel ...
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29
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Accelerate an object in a current-carrying coil
I'm currently trying to come up with some concept ideas for a physics game / riddle. The player has to get an object from one side of a horizontal, current-carrying coil to the other end of the coil ...
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Relationship between how fast a metal cylinder can spin on its axis without breaking or deforming?
For simplicity sake consider a solid metallic cylinder which is $2r$ in height with a radius of $r$.
For a given metal and $r$, how to calculate how fast can this spin in terms of rpm for a very long ...
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124
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Find the Angles 1 to 3 so that the Reactional Forces Become Minimal
My question regards the following system:
This system is supposed to be located in a plane, so it is 2-dimensional.
It consists of three rods, which are connected at the ends. Meeting in the hinges $...
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2
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79
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Why can’t we accelerate a rotating object after some point?
If I push an object in a linear way with constant force bigger than frictional force on ground, the object will accelerate more and more until air drag force matches it. Logically, If I add the same ...
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Investigation of Body Motion in SolidWorks: Euler Angles Rate or Angular Velocity?
This is my first question in this community.
I decided to demonstrate my problem on simple rigid body, but task may be applied to more complex shapes. So, a cube is built in SolidWorks:
Using the ...
- 226
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39
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How to create a Six Bar Linkage with the Stephenson Topology
I wanted to clarify a point in Mechanical Engineering. To create a six-bar linkage with the Stephenson Topology, do I just have to pick 5 joint locations and connect them with binary links? Then I ...
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60
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Steering with non-zero fork offset
How come the wheel centre O shifts to O* instead of O₁ in the case where we have a non-zero fork offset, when turned sideways? Shouldn't it have shifted to O₁, such that the contact point P₁ lies ...
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Eastward horizontal acceleration
Exercise 2/99 from 6th Ed of Meriam, Kraige - Engineering reads:
An object which is released from rest from the top $A$ of a tower of
height $h$ will appear not to fall straight down due to the ...
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2
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48
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Kinematics of actuated disk with no slip
Given the following kinematic problem, how would one calculate the velocity $v_C$ of point C given a certain horizontal velocity $v_{E}$ in point E? Given is that the disk does not slip and cannot ...
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41
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Kinematic join for parallel axis rotation with equal inverse angles
I'm looking to manufacture a coffee table. I would like the top panel of the table to be split into two parts in order to open the top of the table and get access to a cabinet. Each part of the top ...
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142
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Radial and transverse velocity
A comet at its point of closest approach to the sun where the radial
distance from the centre of the sun is $50\times10^6$ miles, has a
velocity of 188,500 ft/sec. Determine the radial and transverse
...
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33
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Confusion with Measuring Velocities in a Translating/Rotating Reference Frame: Combining Transport Theorem and Homogeneous Transformations
The inertial reference frame is denoted by $I$, the position, velocity, acceleration, angular velocity, and angular acceleration of reference frame $S$ is measured in the inertial frame, reference ...
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235
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How to calculate the degrees of freedom, constraints and the generalized coordinates in this dynamic system
The rope lengths are taken to be constant.
Solution:
$N$ particles with $k$ constraints.
. Then the Degree of Freedom (DOF) is $3N-k$.
In Figure 1, we have two particles $m_1$ and $m_2$, so $N=2$. But ...
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3
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Why does the velocity of the two objects changes "gradually" after the collison?
Theoretically, after a collision, the velocity of two objects must be changed by the law of conservation of momentum. But the velocity doesn't go straight from v(a) to v(b), it changes gradually. Why ...
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426
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Difference between body-fixed angular velocity and the rate of change of Euler angles?
I'm visualising the motion of a rigidbody in 3D space with MATLAB and Simulink using this library which implements 6DOF equations of motion based on applied forces and moments.
Here is my model so far ...
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Computing distance traveled jumping from moving vehicle
Ok, here's the background: I'm a BASE jumper and usually I jump from stationary objects like bridges, cliffs, etc.
But one jump I would love to do at some point involves exiting from the roof of a ...
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3
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110
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Calculating two diagonal forces
When I tried to calculate the force exerted on the rope 'a' I get that it is equal to 5N when the block has a force of 10N. Do I instead need to divide by 30 since the sum of the two angles is 30 ...
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2
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86
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What causes damage to my drone when falling down?
I am trying to design a landing gear system and I am stuck at whether I should use a spring as a kind of shock absorber in my landing gear. Currently, the scope of my project is only concerning about &...
- 133
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Forces supporting a beam
I've been struggling with this engineering problem. The forces I've got are Frb=2.08kN, Fray=15.12kN, and Frax=3kN. Before i give in my calculations I need to do a check if they are correct or not ...
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What is the difference between mass moment of inertia and area moment of inertia? And why mass moment of inertia alone used for kinetic rotation?
What is the difference between mass moment of inertia and area moment of inertia and why mass moment of inertia alone used for kinetic rotation? Is there a possibility to use them interchangeably?
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How to model the state space matrix of a pendulum?
Here's an image of the problem:
I'm trying to put the following problem in matrix form (state space) but I don't know how would I put -(g/L)sin(x1) in the A matrix since the x1 value is inside the ...
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97
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Frictional wheels without slipping (gear system)
In the figure below it is stated that the friction force should always be greater than the tangential force in order to prevent slipping between two frictional wheels. My question is that if we apply ...
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2
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163
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Inertial Force expression in spring
Let there be a spring as shown. And this is stretched to point C and released, then force exerted by spring on mass in region X2 is "- kx" . But This springs gains kinetic energy at mean ...
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2
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258
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Eight bar Linkage (Analytical solution)
Good morning,
I'm trying to solve this problem of kinematics of an eight bar linkage through the analytical method.
I don't want that you perform the calculation, only I would like to have a advice ...
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1
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46
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Summing Displacements of two Cranks and Sliders
Is there a linkage mechanism allowing the summation of the throws of two crank and slider mechanisms oriented next to one another in order to control an output slider with a motion equal to the summed ...
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2
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144
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Torque required to push object hanging from ceiling
I'm trying to determine a suitable motor in order to reciprocate a small wooden table that is hanging from the ceiling for an art installation. I've made a basic diagram that illustrates how I think I ...
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Question about theory of machines (kinematic diagrams)
Can I draw this part of kinematic diagram in this way, knowing that bolded W is a point of interest. so is my drawing true also? (my lines are in red and black(not bolded black))?
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99
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Is there a simple trigonometric relationship between these two angles?
The setup shows 3 rigid links (with fixed lengths) constrained by 4 joints. The blue joints are fixed in place and only allow rotation, while the black joints can move and also allow rotation. ...
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Is there an equation that can automatically tune a PID controller?
Is there an equation that can automatically tune PID controllers? or do I have to do manually/make an AI to do it for me?
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Question about a Force in FBD of a garage door
I am not sure how to draw a certain force in a FBD (Free Body Diagram) of a garage door.
The Garage door is indicated by B-C (2m height) in the picture below. If this door is closing, how should the ...
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630
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Is there a formula that relates the two angles in a crank rocker?
I'm working on a mechanism that requires a crank rocker - is there a formula that relates the angle (to some fixed reference; horizontal, vertical, whatever) of the driving "crank" to the ...
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inverse kinematic of modified Rodriquez parameters
as you know, the attitude of a robot is represented using many ways, euler angles, quaternion, rodriquez parameters, and so on. I should use rodriquez representation in a problem formulated same as a ...
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Where/How to Build a Ball Joint
I am trying to mimic the behavior of the following video:
https://www.youtube.com/watch?v=6pfnKuKy6Lg
I'm interested in the ball joints connected to the platform. I've searched for them online, but I ...
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Modeling rigid body dynamics: Trouble with equations, encountering nonsense answers
Hi, I am working on modeling a simple rigid body dynamic system through a certain range of motion. Here is the picture of the system.
I am trying to solve the system for the variables $x_1'', y_1'', ...
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Solve quaternion kinematic
In a robot or spacecraft attitude representation, using quaternion is relevant.
The kinematic equation is as below
$$
\begin{bmatrix}
\dot{q}_0 \\ \dot{q}
\end{bmatrix} =
\frac{1}{2}
\begin{bmatrix}
-...
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1
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165
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Degree of freedom of a mechanism
A mechanism popped up in my mind when I was studying kinematics, see picture below
$J1,\ J2,\ J3$ are rotational joints and there are two translational joints $J4$ and $J5$ between two sliders and the ...
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3
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139
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Would a car slip down on a frictionless banked road and situation for friction road
Here , we have a car on a banking road. Considering two cases :
Frictionless and friction surface of the road.
I give an initial velocity to the car by a push for a second. Then , the cases discuss ...
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Why do I get pushed back when I’m in a car at high speed?
When I’m in a car at high speed , I get kind of like pushed back if I’m sitting on the cars seat. How does it happen and why ?
If I’m in a car , then I have the same speed as car and for the car , I ...
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Resolving the forces into components [closed]
okay so I am really struggling to see how to resolve the Normal reaction force and Weight into the r and theta direction please? Why is it that the angle is taken to the left of N and right of mg ...
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Inverse of quaternion kinematic matrix
In a robot or spacecraft attitude representation, using quaternion is relevant.
The kinematic equation is as below
$$
\begin{bmatrix}
\dot{q}_0 \\ \dot{q}
\end{bmatrix} =
\frac{1}{2}
\begin{bmatrix}
-...
- 53
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2
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Find the acceleration of a block relative to incline plane in non and inertial frames?
A block can slide on a smooth inclined plane of inclination $\theta$ kept on the floor of a lift. When the lift is descending with retardation i.e. $ a \; m/s^2 $. Find the acceleration of the block ...
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Why does the 1kg mass move towards inclined plane here?
Assumption :All frictionless surfaces.
EDIT: In the book , it doesn’t say friction has to be present but as PeteW has mentioned , i think it should be necessary too. So , in that case let me take two ...
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Number of Kinematic Pairs
Kinematic pairs are the connection between 2 links that can have relative motion between them.
But In six bar chain as shown below:
There are five pairs for them to be a kinematic chain. But if I ...
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Are equilibrium values of a differential equation uniquely dependent on its constants?
I have a dynamic model which undergoes two distinct stages. The system starts out with certain initial conditions and once a specific point is reached in stage 1, these ending conditions are used as ...
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Firing a bullet on wooden block and then finding the average resistive force by block?
For a Q in which we are firing a bullet of 0.04kg onto a wooden block which is stopped after a distance of 60cm after penetrating inside it. It’s u=90m/s.
For this Q , we can find a=-6750m/s^2. Using$ ...
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Why is final momentum found by two formulae in case of increasing force not equal?
So, let us say a body moves with 10 m/s, mass = 10 kg.
At time t=0 a force of 30 N is acting on it. Gradually (linearly) the force increases and finally it becomes 130 N after a period of 2 second .
...
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