Hot answers tagged

8

You're trying to implement more PIDs than you have degrees of freedom. In a quadcopter, you have only 4: $(Z, \phi, \theta, \psi)$ i.e. (Altitude, Roll, Pitch, and Yaw). via (http://www.draganfly.com/uav-helicopter/draganflyer-x4/features/stability.php) Interestingly, from a PID perspective you definitely do have desired values for $\phi$ and $\theta$: ...


8

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, $$ \dot{v} = -\frac{b}{m} v +\frac{1}{m} u $$ where $v$ is the speed, $u$ is the externally applied force, and $bv$ is some viscous damping force. Now if the viscous damping coefficient is zero (no ...


7

As others have said in comments, a screw is probably your best bet. It's mechanically pretty simple to set up, and could be made to look fairly tidy, which is always nice in a home. But the main problem, as always is going to be doing this on the cheap. The cost of the parts soon adds up. Even if your motors are only $15, you still need to buy the lead ...


7

Your mechanism will depend on the type of dispenser you want. Like if its gravity feed or not. I will assume it is, so I make this sketch to give you some idea: The hole size will depend on how many candy you want to dispense at each stroke. (Of course its related to the candy size). The electro-mechanical actuator can be a crankshaft one, a solenoid, a ...


7

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 calculated shifting of the centre of mass to the appropriate position can achieve desired trajectories of the ball. Apart from the above said principle, a few ...


6

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 swing the racket) Vision processing to track the shuttle Shuttle dynamics to predict shuttle path (this is not well studying so you would most likely have to ...


6

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 $\mathbf{R} \in \mathbb{R}^{3 \times 3}$ is symmetric and $\mathbf{p} \in \mathbb{R}^{3 \times 1}$, then we seek for the inverse $T^{-1}$, such that: $$ T^{-1}=\left( \begin{...


5

You seem to have 2 separate (but related) problems you are trying to solve at once. Let's break down your conundrum into smaller pieces: How do I communicate commands from a slow system (30Hz) to a fast controller (200Hz), and how do I communicate data being received at 200Hz back to my 30Hz thinktank? How do I control what is happening at 200Hz, when I can ...


5

I would say any application where a large number of communications nodes are required (sensors or actuators) would benefit from being implemented as a system bus (in contrast to point to point links such as UART or Ethernet), due to wiring complexity, determinism and modularity. Any control system requires a high degree of determinism, which high bandwidth ...


5

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 include familiarity with and fear of robots, trusting robots and robot rights. Other issues have to do with popularity. You may be interested in reading this ...


5

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 a weight of 100 N held at a torque arm of 1 m. If you want to swing that weight back and forth you could do it at up to 4 Hz, but no faster without damaging or ...


4

There are two good search terms that come to mind. The first one is a "candy machine mechansim", or "dispenser mechanism" (e.g. http://www.woodworkingformeremortals.com/2012/10/make-candy-dispenser.html). There are several models of off-the-shelf pet food dispensers and cereal dispensers that use this method. The second term would be a screw conveyor (a.k....


4

Defining the state of the quadcopter as $\bf{x} = \left[ \begin{matrix} \mathbf{p} & \mathbf{v} & \mathbf{r} & \mathbf{w} \end{matrix} \right]^T$ where $\mathbf{p}$, $\mathbf{v}$, $\mathbf{r}$, and $\mathbf{w}$ are the position, velocity, angular position, and angular velocity of the quadcopter respectively. A simplified transition model for a ...


4

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 of using such seals. Also see boatus.com, which describes how much leakage to allow, and when to repack. Two or three drops of leakage per minute is ...


4

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 must go somewhere. For your proposed solution you would have to balance all of that equipment around the ring running power and control lines all around ...


4

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 need to choose a material and manufacturing process for the part, then acquire the material and skills needed. (Usually people select a process they know how to do ...


4

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 can align the parts, such as by using curves, chutes, vibration, and parts feeding mechanisms. Look up vibratory bowl feeders and cap feeders for examples. ...


3

7 is diameter of propeller in inches and 4.5 is pitch of propeller in inches. Unless mentioned, propeller parameters are mentioned in inches. The Pitch of a propeller is distance covered by the propeller in one full rotation hence measured in inches. This is similar to pitch of a screw.


3

In my personal experience, I hate Google SketchUp. I Recommend that you use CAD Solidworks. Google SketchUp is not meant for gear design. In Solidworks, you are able to create gears however you may and also make it function on a three-dimensional visual on your computer screen. *I personally recommend this to you with great honestly.


3

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 rotational velocity back into linear velocity. I don't think the Ftotal calculation is correct because your estimated weight isn't correct. Kg is a unit of mass, ...


3

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. Since it hasn't been mentioned in the other answers, I want to point out that perhaps the biggest reason for the X shape is to keep the weight in the center, ...


3

web based robotic simulator will be a good project. You can do simulators like gazebo and morse


3

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) often doesn't have the knowledge (or experience) in designing and manufacturing robots. The company that would like to use a robot, often doesn't even have the ...


3

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 a few pieces: Hardware Shape and size (you can't detect the size and shape with a robot easily) Movement of pieces Software Color Patterns


3

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), and how you determine "best" (i.e. are you optimizing for speed, strength, dexterity, etc). And even if you know these things, the metrics you use to ...


2

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 influences from external forces more. This includes both environmental disturbances and self generated motion command updates. One of these is not wanted, and the ...


2

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 drones, they vary greatly in design because each was to meet a specific problem. The approach I took for a sea glider to map an offshore reef and record the ...


2

Here are some that I know of: Solidworks student edition: http://www.solidworks.com/sw/education/cad-faq-students.htm (Free for students who use a school's privately assigned password, otherwise $149) AutoCAD Student version: http://students.autodesk.com/ (Free for students) Google Sketchup: http://www.sketchup.com/products/sketchup-make (Free) FreeCAD: ...


2

Plywood is available in various grades (A, B, C), sanded and unsanded, veneer core or MDF core, and with surfaces of various kinds of woods. I'm not aware of any plywood that will emulate the friction coefficient of Delrin (polyoxymethylene). With some hard, tightly grained, or oily woods (eg ironwood, ebony, teak) or Baltic Birch plywood, it might be ...


2

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 knowledge and the fact that you are lifting 1kg we can say that arm's length * 1kg must be less than the maximal torque of the motor. The stronger the motor - ...


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