# Questions tagged [kinematics]

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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 ...
24 views

### 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 ...
22 views

### 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 ...
• 126
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### Monte carlo analysis using estimated model

With a mathematical model, I have estimated aircraft parameters using the extended Kalman filter. Now I have to verify whether the proposed system is robust against uncertainties. I have estimated ...
20 views

### Differences on methods of solution on problem

It is asked to find the velocity and acceleration of the plataform: Determine the velocity and acceleration of platform $P$ as a function of the angle of cam $C$ if the cam rotates with a constant ...
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1 vote
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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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### STM microscope kinematic movement

I found a project for STM microscope, where kinematic movement is regulated with three fine adjustment screws: STM scan head. I own a double frame with two fine adjustment screws on the diagonal and ...
21 views

### 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 ...
58 views

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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1 vote
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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 ...
1 vote
77 views

### 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 ...
95 views

### 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 ...
1 vote
150 views

### 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 ...
23 views

### 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 ...
65 views

### 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 ...
81 views

### 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 &...
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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 ...
1k views

### 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 ...
• 103
41 views

### 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 ...
73 views

### 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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121 views

### 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 ...
43 views

### 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 ...
83 views

### 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 ...
67 views

### 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))?
96 views

### 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?
106 views

### 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 ...
1 vote
355 views

### 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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32 views

### 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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1 vote
125 views

### 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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### 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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106 views

### Velocity and Acceleration Polygons for Mechanism

I need to determine the velocity and acceleration of point H using vector equations and drawing a polygon. Given data is shown. $\omega$2 is 5.8 rad/s and $\phi$2 is 120 degrees I know how I can draw ...
633 views

### Relation between links and pairs in Kinematic chain

I came across a equation for kinematic chain (for lower pairs only) : L = 2P-4 where L: Number of Links; P is the number of pairs how could this equation be derived ? EDIT: I tried putting values in ...
1 vote
172 views

### Mechanical Engineering: How To Amplify Kinetic Energy In Axial Rotational Gear Machinery? [closed]

When I originally posted this question 2021-04-08, I was inspired by pulley physics, especially after viewing these videos at this link and this link and this link. It is not necessary to go to these ...
71 views

### Linearisation of the Equations of Motion of an Inverted Double Pendulum

I am working to develop a deep reinforcement learning model for balancing an inverted double pendulum. To do so, I needed to derive the equations of motion, via the Euler-Lagrange (EL) method and now ...
1 vote
Let us we are moving in a car. There is a wall in front of us, we need to decide can we go around it or not. It is known that width of the wall is $w$ and our speed is $v = const$. What is a simple ...