# Tag Info

10

Addressing the shoulder joint, which is rather more complicated than elbows and knees... After this one, the other joints become far simpler to visualize or engineer. Here is how the ball and socket shoulder joint could work: Freedom of movement: Approximately 60 degrees end to end, all around. Less than for humans, but it can be tweaked to around 80 ...

7

The answer is 'yes'. A more detailed answer likely depends on how you define "robotics". But generally, robotics applications are considered to require a very broad spectrum of knowledge. So while most robotics includes some form of mechanical function, you could easily specialize in artificial intelligence, microcontroller design, or any number of ...

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 ...

5

2 kgs is not very much, so i would probably consider arms that are slightly less industrial than Kuka, ABB, Fanuc, Denso and the like. However, 1.6m is pretty long and that may be hard to find in non-industrial arms. Keep in mind there are many other factors to consider when choosing a robot arm. human safety, accuracy, repeat-accuracy, speed, workspace ...

5

It's a clever and attractive design, but it's mechanically weak. The mating area between the screw and grooves is small, so the pitch angle of the threads isn't as much of a problem. The grooves on opposite sides are offset by half a thread so the screw has less of a tendency to tilt. Mechanical clearance and deformation of the parts is enough to compensate ...

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 ...

5

There are 2 main reasons why the MER is still operating long after it's 90 Sol planned lifetime. The first is political, strategic, and can be summarized as 'Under promise, over deliver'. When a PI (principal investigator) proposes a high-risk scientific mission like this, they always frame the goals of the project such that their project is viewed ...

4

Working in robotics doesn't mean that you must understand (or enjoy) all the relevant disciplines. It simply means that you must understand that you are one part of a team that produces a robotic system. On the other hand, what skills you have will determine which teams will find you valuable as a member -- smaller teams require everyone to bring multiple ...

4

Whether a single 3-way, 2-position pneumatic valve (typically with a work port, an input port, and an exhaust port ‒ see page 3 of nationalpneumatic.com's pdf about valves) will suffice depends on information not given in the question. For example, if you can turn the compressor on or off at will, and if it will hold pressure when off, you can attach the ...

4

For most applications, I think the calculation you describe is good enough when selecting hardware. You want your arm to be able to have some lift capacity at the worst case, which is when the arm is fully extended. Note that you should also take into account the weight of the arm itself which is typically non-negligible. That being said, yes, there are ...

4

So this is summary...Open to discussions or edits... | Mechanism | Precision | Friction | Max length | Max force | |--------------------| ----------|----------|------------|-----------| | rack and pinion | low | high | unlimited | high | | lead screw | high | mid | limited | high | | ball screw | ...

4

The video shows 2 linear actuators driving a universal joint through ball and socket joints.

3

Rotary mowers are mechanically simpler, so cheaper to make. The rotary mower is more tolerant of getting dull, and if you run over something like small trees or rocks, the blades take less damage, and the motor is harder to jam and stall. The blades are also easier to sharpen. For this simplicity, you get a poorer cut, and more grass damage. I do agree, ...

3

I think there might be different reasons for this. First, historical reasons The first systems with haptic feedback were mechanical systems to which vibration / force feedback functions were added (vibrations in a pilot's handle, for instance). In the early stages robotic systems were used as haptic displays for different uses (quite early, force feedback ...

3

Flow-rate meters based on measuring Coriolis-force reactions are widely used in process control systems. The measurement principles are mentioned or illustrated at numerous web sites, including youtube video e2NGvrkmP8Y, Back to Basics: Flow Measurement (Corilolis) (via oscillating-tube phase changes) and Schenck Americas' Solids Flow Meters page, Coriolis ...

3

Shafts can be constrained with e-clips, snap rings, shaft collars, set screws, spacers or threaded holes at the end of the shaft with washers. McMaster.com is usually a good place to look for different shaft collars and mechanisms, especially if you don't know the exact name. They have an excellent picture reference and sorting feature for sizes and ...

3

Many shafts and spindles have shoulders (ie, a ring-shaped surface at the junction of different shaft diameters) turned on them to serve such a purpose. If there is no diameter change in the shaft you are working with, shaft collars sometimes are used to keep the shaft from sliding back and forth. The wikipedia article mentions several kinds of collars. ...

3

I'm looking for a way to create a non-rotating persistence of vision device. It seems to me that the two designs that you propose yourself, at least rely on rotation. I would suggest getting rid of rotation entirely. In particular since you say you have problems swinging these arms around. One way to go about this, is by using magnets, springs and electro ...

3

Yes, general question. Here's some general bits-o-answer: some assembly is required. First, I would leave the decision about stepper vs. some other kind of motor until later -- it should be a tactical, not a strategic, decision. Second, assuming that the positive displacement idea works at all, I would assume that at the core of your machine you still ...

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

Erik, your wish is my command: "High torque pancake stepper motor" comes to mind. Can you develop one, and a couple of extra's? :) Seriously, you're looking at a combination of technologies and disciplines. Precision positioning of a "High torque pancake stepper motor" might be an acceptable direction, but it'll probably end up simply being the ...

3

I assume that your 2 channels control forward/backward and left/right. But even if the 2 channels control forward/backward in each wheel (differential-drive style), it should still be possible to do what you are suggesting electrically instead of mechanically. You should be able to read the input signal to the motors, decide whether those signals are ...

3

What about using a simple RC-servo with a rotating cam that holds one pod. When rotating down It would drop the pod it is holding. When rotating up, it would lift the whole stack for one pod height and allow the bottom pod to drop into the cam's holding space.

3

For your first example, Max-Weight = Torque/arm-length. Going beyond that, there are several software applications and API's out there that can be a big help for these kinds of calculations (matlab or pyODE to name a couple), but they will be pretty useless without a decent understanding of what you are computing. A good resource to learn about the mechanics ...

3

Books FIRST and VEX are fairly large competitions, so it should come as no surprise that people have literally written books on how to participate. My favorite book aimed at FTC is FTC Robotics: Tips, Tricks, Strategies, and Secrets. They've made several editions of this book; although it's not a structured curriculum, it is a great guide and a must have ...

3

I don't think they're proposing building a compressor for use in refrigeration. They're proposing a solid-state cooler/heat pump based on the elastocaloric effect: As the shape memory alloy block is strained, it gets hot. This heat would be extracted - I guess by blowing air through the device to somewhere outside the refrigerator? The air flow is then ...

3

Going forward, a Klann linkage has a near-vertical leg drop action. (See the legs at left in the wikipedia animated GIF.) It has a near-vertical leg lift action if running in reverse. (See the legs at right in the illustration.) Note, this linkage and some other leg mechanism linkages use a rotary crank; ie, rather than using a 180° back-and-forth motor, ...

3

If I understand correctly, you are referring to when the robot spins and the rack remains stationary (dynamic motions involving the rack mass seem to be slow as you would expect with such a high COM). In this case only the kinematics are important. It's important that the rotational axis of the wheels and the rotational axis of the rack-support are ...

3

They are parallel manipulators. You may find chapters on parallel manipulators in robotics textbooks, for example, A Mathematical Introduction to Robotic Manipulation, useful. There are also a number of articles related to kinematics analysis of those manipulators (such as this article).

3

I will try not to skip too many steps. Assuming a Global coordinate frame at the base and the arm is fully extended along the Y-axis of the base frame. Since SCARA has four joints, we will create four 6D spatial vectors (screws) ${ξ}_{i}$ with respect to a global coordinate frame. Keep in mind that all spatial vectors are described with respect to the ...

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