Questions tagged [kinematics]
The kinematics tag has no usage guidance.
85
questions
-1
votes
2answers
64 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 ...
0
votes
1answer
34 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 ...
0
votes
0answers
30 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 ...
0
votes
2answers
56 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 ...
0
votes
1answer
56 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))?
0
votes
3answers
92 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. ...
0
votes
0answers
41 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?
0
votes
1answer
66 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
1answer
130 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 ...
2
votes
0answers
29 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 ...
1
vote
1answer
91 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 ...
3
votes
1answer
181 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'', ...
2
votes
0answers
54 views
Solve quaternion kinematic
In a robot or spacecraft attitude representation, using quaternion is relevant.
The kinematic equation is as below
$$
\begin{bmatrix}
\dot{q}_0 \\ \dot{q}
\end{bmatrix} =
\frac{1}{2}
\begin{bmatrix}
-...
2
votes
1answer
60 views
Degree of freedom of a mechanism
A mechanism popped up in my mind when I was studying kinematics, see picture below
$J1,\ J2,\ J3$ are rotational joints and there are two translational joints $J4$ and $J5$ between two sliders and the ...
2
votes
3answers
94 views
Would a car slip down on a frictionless banked road and situation for friction road
Here , we have a car on a banking road. Considering two cases :
Frictionless and friction surface of the road.
I give an initial velocity to the car by a push for a second. Then , the cases discuss ...
1
vote
3answers
238 views
Why do I get pushed back when I’m in a car at high speed?
When I’m in a car at high speed , I get kind of like pushed back if I’m sitting on the cars seat. How does it happen and why ?
If I’m in a car , then I have the same speed as car and for the car , I ...
0
votes
1answer
37 views
Resolving the forces into components [closed]
okay so I am really struggling to see how to resolve the Normal reaction force and Weight into the r and theta direction please? Why is it that the angle is taken to the left of N and right of mg ...
1
vote
1answer
68 views
Inverse of quaternion kinematic matrix
In a robot or spacecraft attitude representation, using quaternion is relevant.
The kinematic equation is as below
$$
\begin{bmatrix}
\dot{q}_0 \\ \dot{q}
\end{bmatrix} =
\frac{1}{2}
\begin{bmatrix}
-...
1
vote
2answers
72 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 $. Find the acceleration of the block ...
0
votes
2answers
78 views
Why does the 1kg mass move towards inclined plane here?
Assumption :All frictionless surfaces.
EDIT: In the book , it doesn’t say friction has to be present but as PeteW has mentioned , i think it should be necessary too. So , in that case let me take two ...
0
votes
0answers
84 views
Number of Kinematic Pairs
Kinematic pairs are the connection between 2 links that can have relative motion between them.
But In six bar chain as shown below:
There are five pairs for them to be a kinematic chain. But if I ...
1
vote
0answers
47 views
Are equilibrium values of a differential equation uniquely dependent on its constants?
I have a dynamic model which undergoes two distinct stages. The system starts out with certain initial conditions and once a specific point is reached in stage 1, these ending conditions are used as ...
2
votes
1answer
45 views
Firing a bullet on wooden block and then finding the average resistive force by block?
For a Q in which we are firing a bullet of 0.04kg onto a wooden block which is stopped after a distance of 60cm after penetrating inside it. It’s u=90m/s.
For this Q , we can find a=-6750m/s^2. Using$ ...
0
votes
2answers
64 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 .
...
2
votes
0answers
48 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 ...
0
votes
0answers
14 views
How to show that the total angular velocity vector of a rigid body is the sum of all angular velocity vectors acting on it
I am trying to prove the additivity propety for the angular velocity vectors acting on a body in three dimensions. Particularly also in the case when the axes of rotation do not cross each other (the ...
2
votes
1answer
209 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
3answers
84 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 ...
2
votes
1answer
50 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
0answers
24 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 ...
2
votes
1answer
68 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 ...
3
votes
2answers
525 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 ...
1
vote
3answers
81 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 ...
1
vote
2answers
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 ...
3
votes
1answer
145 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
20 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 ...
2
votes
1answer
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 ...
3
votes
0answers
30 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 ...
1
vote
2answers
60 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
35 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
92 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. ...
0
votes
1answer
47 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 velocities are: $\omega_2$ (precession), $\omega_1$ (nutation) and ...
3
votes
0answers
28 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 ...
-2
votes
1answer
41 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 ...
2
votes
1answer
28 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:
$\...
2
votes
1answer
51 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 ...
3
votes
1answer
133 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 ...
2
votes
1answer
98 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
54 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 ...
2
votes
1answer
1k 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 ...
