I am working on a handmade 3D printer. I have two pieces of Nema - 11 Bipolar Stepper motor for my project and I want to connect it directly to vertical crank as in the picture. (There is no extra element such as stepper pulley) These steppers will carry a total of 40 kgs for movable bar.
This picture is an example. So, how can I calculate maximum total lifting weight of these two steppers? Is These steppers enough for this project? In another case, which type stepper can I choose for this 3D printer? Do you have any suggestions for this?
Although your question is pretty off-topic I'll give you a few hints.
Basically all you have to do is google "ball screw force" or "ball screw torque"
http://www.nookindustries.com/LinearLibraryItem/Ballscrew_Torque_Calculations
There are also calculators available:
http://www.daycounter.com/Calculators/Lead-Screw-Force-Torque-Calculator.phtml
Related
I'm doing a robot navigation and path planning project based on simulating the turtlebot3 and driving with the A* planner.
I'm using a program that allows the robot to plan a route only through 'cells' with no cost value (aka. freespace with an inflation cost of 0). However, adjusting the inflation radius I'm experiencing that the robot either cannot pass through narrow openings when the inflation is higher, but drive along a wall when it is low.
I'm wondering if there is a way to control the inflation or something? My desires outcome is for the robot to drive in the center of wide hallways, not along walls, but be able to pass through doors that it should be able to fit through.
Thank you.
I managed to solve this problem thanks to some advice that made me look outside the box.
The problem was intrinsic to my planner, the fact that allowed space to navigate through was binary (aka. either perfectly allowed to drive through or not allowed).
Instead I changed it so that all space other than the walls were allowed space, and added the cost of a cell (from the cost map) to the cells. That way instead of being binary whether the drive can or can't drive in a cell, both the distance and cost of the cells affect the robots path, making it try to keep away from walls, but able to pass through places of high cost if there's no other way.
I am entirely new to iOS, and for my first project I am trying to make a chaos game app, which naturally requires a large number of points be drawn. Ideally, I need 10^5 to 10^6 individual pixel points for the illustrations.
This is a performance concern. Right now, I am using CGRect with very small height and width, is there a less expensive way to do this?
I dont need to draw all of the dots at once, but I do need them to appear on screen over a reasonable period of time to show the progression of the emerging fractal.
I am making an ios application in which it is to be determined that wether the person is sitting or standing.I wanted to know that if there is any method to find automatically that the person is sitting or standing like we can get the height from sea level with the help of CLLocation Manager.So like this can we get the height of iPhone from the ground level in any way?
This is not possible for the following reasons:
The phone can tell you its height above sea level, the accuracy of which has a larger margin of error than the difference between a sitting and a standing person
Even if 1. did not apply, and you knew the precise height of the ground at your current location and the additional height of the phone, this would still be meaningless, as it doesn't take into account buildings, the height of the person, their posture and so forth.
You may have more luck using the motion coprocessor on newer models, you could assume that a standing person moves about more than a sitting person, or something. Or accelerometer readings to detect changes of position. But altitude is definitely not the way to go.
You cannot find out by altitude if a person is standing or sitting.
Accuracy of GPS is much to low. Which is at best 6m for altitude.
But if you are really clever you could try other approaches:
-Use the acceleratoin sensor: A standing person might move a bit more than a sitting one, or moves different. [Sorry, I did not saw that user jrturton has written the same, bit this indicates that this might work]
Sitting persons often type on the keyboard. You can measure that with the accelerometer, by frequence analysis after doing a FFT.
Walking persons: A person that walks does not sit: Detect typical walking steps, with aclerometer or even with an ios API that is new in ios7. (I remeber there is a step counter)
These all are no accurate detections, but may raise the probability to detect a sitting person-.
If you get that to work, I will have major respect. Post an update if you succeed.
Expect 2,5 to 3,5 fulltime working month to get that to work (in some cases)
I have a requirement mentioned below:
Already have a floor plan map image
First detect current location on floor
Then select the destination location using floor plan map image
Now application should provide direction & distance for that source to destination path
This is like how google direction works, but its in-house map require.
For example,
- Current position of user is: At his desk
- Where is Meeting Room #11
- So application should provide direction and distance updates on the map/floor plan image.
Any kind of suggestions/help would be great.
Thanks in advance
Couple of points...
You could create various audio files and play them as way points based on routing. Same principal as 'turn right at the next light'.
Definitely want to set your accuracy to: kCLLocationAccuracyBest. But this will still probably only get you accuracy of around +/- 10 meters at best.
Do a floor plan overlay using MapOverlayView.
If you are indoor, iPhone uses cell towers or WIFI for a location fix. This might be a problem for you because if you are looking to map multiple floors, only GPS can give you altitude readings - ground floor, second floor, etc...
I don't want to pour cold water on your idea but I have not heard of anyone successfully doing an indoor navigation app on an iPhone using standard stuff. If you really wanted to move forward on this project, your best accuracy might be using indoor bluetooth transmitters as navigational beacons...?
What you want is path-planing in the map, is that? If so, there is lot of algoritms you can use. You can choose a block size based on your map and resolution needs, divide de map into this, amd mark each block as navegable or not. Then getting from the first block trying in the direction of the destionation block, check if the neighboor block is blocked or not, and get going, until you reach (or not, if its not reacheable) the destination block.
Thats a pseudo-implementation, you have some option to do it, if I understand your needs.
(I dont know your hardware as said by others, with simple GPS and indoor navigation, assuming a 15m resolution is a good balance between optimistic/pesimistc signal, If its for robot-navigation, its not a goos approach in the GPS terms, but the algorimt is).
At first I think my question should have been asked before, but I didn't find what I want.
One element of this iOS app I'm developing is break a 8x8 grid into Tetris pieces (every piece is made of 4 blocks). Two particular question I have are:
what is the best way to represent a Tetris piece in objective-C?
what algorithm to present the grid into random Tetris pieces (and later on how to check if two pieces fits together).
Edition on 01/28
#livingtech, I think I implemented pretty much what you say, except the point of "having a hole". My code works with no hole at simple stage when Tetris block is two blocks only (yes, two squares, connected either horizontally or vertically), but at 3-square Tetris block, I would get holes. I just tested and out of 1000 running, I would get one without a hole. So definitely I need some mechanism to check if next square will be a singleton.
I been trying to do the same thing for my game. Though I am a total beginner, and I'm using XNA and C#.
But the way I'm trying to go about it is: 4x6 grid array
--y123456
X1-000000
X2-000000
X3-000000
X4-000000
Here,
0 signifies no block
1 defines a block
Algorithm
Start by taking the very first 0 in the array ( top left corner )
and randomly pick a 0 or a 1.
Randomly choose the coordinates based on x1/x2-y1/y2, decide 1 or 0.
If it is 1, then decide coordinated based on where that 1 was put.
If it was 1 on x2 y1, then decide if a 1 should go on next touching
coordinate.
If you just have to code in what coordinates touch and which don't,
and the logic will roll through.
I have mine set up bit different. But this is the basic foundation of my random Tetris engine.
I also found that making it like that really helps to have a whiteboard and make a drawing of the grid and label with your coordinates.
since ur board is 8*8, i think u can use a int64 to represent the board. each bit of the int64 represents whether the specific grid is filled or not.
Implementing Tetris is a hobby of mine. First implemented it in Windows/C. Then in Perl/Tk! Last implementation I did in Obj-C/Cocoa (Mac). In all cases, the game logic is the same. Only the UI stuff changes. I treat every little box separately and have a two-dimensional array which contains the presence (and color) of every "set" box on the board. Standard board size I use is 10 boxes wide by 20 boxes high.
Separately I keep track of the "dropping" piece: it's location and what kind of piece it is. Based on a timer, try to make the piece drop. If any of the boxes where the "dropping" piece would drop is already set, then stop dropping the piece and add the piece boxes to the "set" part of the board. Create a new piece, and start over.
It may not be the best way to implement it, but it makes sense in my head. From a pure OO perspective, each shape of a dropping piece could be a subclass of a generic shape class. Override functions that check whether the shape can drop, the offsets of the individual boxes in the shape, etc.
I don't think anybody has taken a stab at your question #2 yet here, so I'm going to outline what I would do.
Setup:
You'll need to represent your grid as an array of some kind. At the very least, you'll want some kind of boolean values, to denote whether each coordinate in the grid is "occupied".
You'll need to keep track of the pieces on your grid. This could be another array, this time holding references to the four coordinates for each piece.
You'll need a variable or variables to keep track of a coordinate in your grid where you'll start filling in pieces, (I would probably populate these with a corner to start).
Set up a "pool" of all possible Tetris pieces and rotations. (You'll want to keep track of which ones you've already checked on every iteration outlined below.)
Iterate:
Get a random piece from your pool that will fit into your starting coordinate. (If you want to get fancy, you could be smart about which ones you choose, or you could just go totally random. As pieces don't fit, mark them checked, so you don't keep checking randomly forever. If you get to a point where you've checked all the pieces, you have a solution that doesn't work, either back up an iteration, or start over.)
Make sure the Tetris piece you selected didn't leave a "hole", or empty space with less than 4 squares. (I don't know your requirements for solving this problem, so I can't say whether you should focus on speed or ease of coding, but you may be able to skip this step if you want, and "brute force" the solution.)
"Place" the piece, by writing it to your piece array and marking the coordinates filled.
Check for "finished" condition, in which all your spaces are filled.
Pick a new coordinate in your grid and repeat #1. (I would pick an empty one next to the previous coordinate.)
If this actual yet, I wrote test tetris app on Objective-C few months ago https://github.com/SonnyBlack/Test-Demo-Tetris . I think my algorithm not very well, but it working. =)