Questions tagged [kinematics]

The tag has no usage guidance.

Filter by
Sorted by
Tagged with
0 votes
3 answers
65 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 ...
user avatar
0 votes
1 answer
41 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 ...
user avatar
0 votes
1 answer
22 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 ...
user avatar
0 votes
2 answers
46 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 ...
user avatar
0 votes
2 answers
80 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 &...
user avatar
0 votes
1 answer
17 views

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 ...
user avatar
  • 1
0 votes
2 answers
257 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?
user avatar
  • 101
0 votes
1 answer
130 views

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 ...
user avatar
  • 103
0 votes
1 answer
33 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 ...
user avatar
0 votes
2 answers
47 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 ...
user avatar
  • 11
-1 votes
2 answers
91 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 ...
user avatar
0 votes
1 answer
40 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 ...
user avatar
0 votes
0 answers
36 views

Slider crank with inclined slider

I'm a qualified mechatronic engineer but have only worked in firmware since graduating, so I'm a bit rusty on my kinematics 😅 I have a system as so; https://imgur.com/a/YHBv1Jb This system is a ...
user avatar
0 votes
2 answers
64 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 ...
user avatar
-1 votes
1 answer
65 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))?
user avatar
0 votes
3 answers
95 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. ...
user avatar
  • 13
0 votes
0 answers
48 views

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?
user avatar
0 votes
1 answer
87 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 ...
user avatar
1 vote
1 answer
194 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 ...
user avatar
  • 113
2 votes
0 answers
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 ...
user avatar
  • 53
1 vote
1 answer
107 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 ...
user avatar
  • 111
3 votes
1 answer
196 views

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'', ...
user avatar
2 votes
0 answers
63 views

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} -...
user avatar
  • 53
2 votes
1 answer
74 views

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 ...
user avatar
2 votes
3 answers
100 views

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 ...
user avatar
  • 669
1 vote
3 answers
438 views

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 ...
user avatar
  • 129
0 votes
1 answer
38 views

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 ...
user avatar
1 vote
1 answer
79 views

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} -...
user avatar
  • 53
1 vote
2 answers
85 views

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 ...
user avatar
  • 669
0 votes
2 answers
79 views

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 ...
user avatar
  • 669
0 votes
0 answers
169 views

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 ...
user avatar
1 vote
0 answers
47 views

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 ...
user avatar
2 votes
1 answer
51 views

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$ ...
user avatar
  • 669
0 votes
2 answers
67 views

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 . ...
user avatar
  • 669
2 votes
0 answers
68 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 ...
user avatar
2 votes
1 answer
357 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 ...
user avatar
1 vote
3 answers
124 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 ...
user avatar
2 votes
1 answer
57 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 ...
user avatar
1 vote
0 answers
28 views

Sprocket Angular Velocity [duplicate]

I have a question please that I need help on. Consider the chain that is draped over the sprocket with mass moment of inertia of 0.005kgm^2 about central axis. If 4kg block is released from rest from ...
user avatar
2 votes
1 answer
69 views

To stop or to go around?

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 ...
user avatar
3 votes
2 answers
870 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 ...
user avatar
1 vote
3 answers
88 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 ...
user avatar
  • 669
1 vote
2 answers
42 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 ...
user avatar
  • 669
3 votes
1 answer
271 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 ...
user avatar
0 votes
0 answers
22 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 ...
user avatar
2 votes
1 answer
29 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 ...
user avatar
  • 65
3 votes
0 answers
34 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 ...
user avatar
  • 65
1 vote
2 answers
65 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 ...
user avatar
-1 votes
1 answer
38 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,...
user avatar
  • 1
4 votes
2 answers
94 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. ...
user avatar
  • 49