Questions tagged [kinematics]

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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 ...
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
442 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 ...
4
votes
2answers
91 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. ...
4
votes
2answers
2k views

Applications of Five-Bar Mechanisms

I have some university work to do based on a real world application with five or six bar mechanism, but I am unable to find such a device. Are there real applications of such mechanisms? I've ...
3
votes
1answer
396 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. ...
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 ...
3
votes
2answers
167 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 ...
3
votes
1answer
12k views

GIM Mechanism Software (Kinematics / Analysis / Synthesis)

I've recently discovered a very awesome software tool for the synthesis and analysis of mechanisms. The tool is called GIM, from Faculty of Engineering in Bilbao, Department of Mechanical Engineering,...
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 ...
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 ...
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
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 ...
3
votes
0answers
38 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
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 ...
2
votes
2answers
145 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 $\omega$: ...
2
votes
1answer
64 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 ...
2
votes
2answers
98 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 ...
2
votes
1answer
46 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 ...
2
votes
1answer
957 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)...
2
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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 ...
2
votes
0answers
25 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
96 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
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 ...
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 ...
2
votes
0answers
918 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 ...
2
votes
0answers
99 views

Mechanical device to simulate hinge axis external/off of part

Take a horizontal bar 10' pinned on the right end, so that there is a hinge point on the right end. Space requirements dictate that the bar must be cut in down to 5' (cut in middle and keep the left ...
1
vote
1answer
672 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 ...
1
vote
1answer
19 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
107 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 ...
1
vote
3answers
153 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\...
1
vote
1answer
281 views

4 bar mechanism how does this 4 point method work

I'm wondering if somebody could explain the 4 position method a bit more understandably. I am trying to follow the explanation in here. What I fail to understand is how does the actual fourbar linkage ...
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 ...
1
vote
1answer
771 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 ...
1
vote
1answer
44 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 ...
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
34 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
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 ...
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 ...
1
vote
0answers
332 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
0answers
98 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 : $...
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 ...
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 ...
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
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3answers
58 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
1answer
203 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
115 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 ...
0
votes
1answer
170 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 ...
0
votes
0answers
16 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 ?
0
votes
0answers
17 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 ...