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8 votes
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Can a state matrix have a row of zeros?

Yes, a state matrix with zero rows and/or columns makes sense and is viable. It typically signify pure integrators in the system. In the example you give, $$ \dot{v} = -\frac{b}{m} v +\frac{1}{m} u ...
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  • 375
7 votes

Sphero's logic, how does it work

The principle lying underneath the sphero robot's design and locomotion is shifting of the centre of mass of the ball and making it unstable which makes the ball roll [1,3,4,5,6]. A controlled and ...
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  • 173
6 votes

What are the calculations for a badminton robot and mechanisms?

In short, what you are trying to do is well beyond the capabilities of top robotics research labs. That said, here is a short list of general areas you need to look into: Robotic arm dynamics (to ...
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  • 2,669
6 votes

Inverting a transform (Reading J Craig's book on Robotics)

Given that an homogeneous transformation $T \in SE\left(3\right)$ can be expressed as $$ T= \left( \begin{matrix} \mathbf{R} & \mathbf{p} \\ 0 & 1\end{matrix} \right), $$ where $\mathbf{R} \in ...
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5 votes
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How important are events like "Robocup" to the advancement of Robotics in general?

Robotics is a relatively new field of study. Besides technological problems, there are psychological and even moral issues that need to be resolved. Some examples of these non-technological issues ...
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5 votes
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What is torque bandwidth in actuated joints and how does it affect the control systems?

The torque bandwidth is typically referring to the maximum frequency of motion at which the actuator can provide that torque. So your actuator can provide a peak torque of 100 Nm, as in it can hold up ...
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  • 1,357
4 votes
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Submarine screw and the isolation from the water

A variety of techniques are used for propeller shaft sealing. One of the most common is a "packing gland" or "stuffing box", as in illustration below from a dieselduck.info web page which has details ...
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4 votes
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Quadcopter frame design

A frame in that configuration or any other witch holds the props in a square without being unbalanced would work, the reason that most people do it with cross bars is because the FC batteries and ESCs ...
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  • 1,909
4 votes
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How to get manufactured part from CAD file?

I think this is a great question. The two basic options are make it yourself or have someone else make it. EDIT: check the bottom for a third option... Make it yourself To make it yourself you ...
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  • 4,205
4 votes
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Is it better to use software or hardware for object sorting?

It really depends on the objects you are sorting, and the flexibility you're looking for as the system is maintained over the years. Using physical methods to sort is very reliable. Many times you ...
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  • 4,326
3 votes

Quadcopter frame design

To answer your questions directly, the X-shape is not the only design that will work. There are many variations of frame design around a number of rotors that can range from 3 to (in some cases) 8. ...
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3 votes
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How to find a solution for quadcopter PID control

The forces used to control the quad act around its center of mass, causing it to pitch, roll or yaw. Changes in the roll angle are induced by contrary variation of speeds in propellers A and C. Same ...
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  • 344
3 votes
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Verifying motor selection calculations

I think your Pmotor calculation is correct. The reason for the difference with the CIRC link is in the P=F*v equation they are referring to the linear velocity. Your conversion is converting the ...
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  • 181
3 votes

idea for web application in robotics

web based robotic simulator will be a good project. You can do simulators like gazebo and morse
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  • 1,084
3 votes
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Create 2 CAD files

The CAD you pointed out is for the Turtlebot, and includes electromechanical CAD for that assembly. I only spot-checked a few files, but the only Create-relevant CAD in that package I found was an STL ...
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  • 952
3 votes

Design in the robotics world

Robots are often made multi-purpose. They're usually not redesigned for every other application, that'd cost quite a lot. A company that would like to use a robot, (let's say a packaging company) ...
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  • 221
3 votes

Is it better to use software or hardware for object sorting?

You would have to do both. It's very very challenging to move an object without using hardware, and it's incredibly hard to see the colour of a brick with hardware. You'd have to break it down into ...
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  • 141
3 votes

What should be the ideal ratio for link lengths ( L1/ L2) of a 2 link manipuator robot with revolute joints?

This is a good question, and one you should definitely consider when designing a new robot arm. But unfortunately, it depends a lot on the configuration of your arm (i.e. how the joints will be bent),...
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3 votes
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How to perform decoupling between decision making and action execution in ROS2?

As a general rule of thumb, publications and topics are good for streaming data and commands where they're flowing continuously. Services are better for handling singular events that are not repeating ...
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  • 1,041
2 votes

How to decide about the length of a robotic arm, the base of it and the torque?

Every motor has a torque described in kgcm units. 1 kgcm means that the motor can lift 1kg weight on a distance of 1cm from the axis of rotation, or 0.5kg at the distance of 2cm and so on. Using that ...
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2 votes

Is it better to have batteries distributed at the rotors or the center of the multicopter?

Vince has it right, it is a designers choice. Depends on the application. Moving the mass away from the center point of rotation will increases the moment of inertia. Which means it will resist ...
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  • 21
2 votes

Choosing the right dimensions for an underwater glider

This is a classic design problem. It starts with want you want something to do - a design specification. Hence there is no one right answer. I have designed a number of both aerial and underwater ...
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2 votes

Alternative way to perform Pole zero cancellation?

Pole/zero cancellation is discouraged primarily because in practice it is almost impossible to do perfectly. Real systems have variation and uncertainty so you can't know for sure where the poles/...
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2 votes
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LQR design with low effort

With LQR you can either decrease $Q$ or increase $R$. If that's not working you have to consider the possibility that your motor just will not work. It also might be worth looking at different ...
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2 votes
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What type of mechanism is this?

Totally off topic and not really robotics related but that's an old gearless angle drive. Kind of like this... http://www.cal-vantools.com/p-5-90-degree-gearless-angle-drive38.aspx
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2 votes

Autodesk Inventor 2013: Rounding only at specific edge

The problem is the fillet is reaching the long edge by following the smooth curve around your previously-filleted edges. The solution is to undo or delete features to get rid of the existing fillets ...
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2 votes

Why Make Bipedal Robots?

In addition to the reasons given by Ugo, studying humanoid robots in general helps in the medical field too. Trying to understand what sensors/systems robots need helps us understand what sensors/...
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  • 2,669
2 votes

Why Make Bipedal Robots?

I would say: Compactness of the structure: imagine humanoid robots that are required to operate in household environment: two-legged robots might have less difficulties in navigating among tables and ...
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2 votes

How to distribute tension load on a three footed claw?

Tension distribution is easily accomplished using a simple mechanism called a whiffletree. Classically invented to allow several horses of different strengths to pull evenly on a single load, this ...
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  • 485
2 votes
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PCB making at home

A slightly better method for home-made PCBs is to mill the copper off of a two sided PCB. Google pcb milling for many machines and services. Another crazy idea that will probably get more affordable ...
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  • 5,215

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