# Questions tagged [kinematics]

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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 ...
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 ...
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 ...
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. ...
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 ...
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. ...
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 ...
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 ...
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,...
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 ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 $\omega$: ...
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 ...
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 ...
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 ...
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)...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
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 ...
19 views

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 ...
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 ...
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 ...
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 ...
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. ...
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 ...
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 ...
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 ...
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 ...
98 views