I need some help writing a function block which I can use to record the travel distance of an axis. This should record every time the axis moves sort of like an odometer, this value will be used for preventative maintenance on the axis. ie greasing the ball screw and linear bearings.
The function has to ignore chatter on the axis when it is not moving and accomodate the homing function which overwrites the position several times.
You can achieve this by integrating absolute value of axis set velocity.
VAR
lrCycleTime_s : LREAL;
lrVelocity_mmPerCycle : LREAL;
lrDistance_mm : LREAL;
END_VAR
======================================
lrCycleTime_s := UDINT_TO_LREAL(_TaskInfo[GETCURTASKINDEXEX()].CycleTime) / 10000000; //Get cycle time in seconds
lrVelocity_mmPerCycle := Axis.NcToPlc.SetVelo * lrCycleTime_s ; // Convert velocity per second > per cycle
lrDistance_mm := lrDistance_mm + ABS(lrVelocity_mmPerCycle);
Remember to execute this in a task with cycle time equal to your motion cycle time (default is 2ms)
Related
I have a servo motor, and this servo motor I would like to make it follow a "motion pattern" as closely as possible, and use the same value for acceleration and deceleration.
The attach picture illustrates the "motion pattern" (Y = velocity, X = Time)
motion pattern:
accelerates 0m/s to 0.100m/s.
constant velocity 0.100m/s for 4 sec.
decelerates to negative ?m/s.
accelerates to 0m/s, and motor position = 0.
How can i calculate the acceleration and deceleration?
What i have tried so far is:
Time = (total time - constant velocity time) 10 - 4 = 6sec.
Distances = (total distances - constant velocity distances ) 1 - 0.4 = 0.6meter.
acceleration = (2 * distances / (time^2) 2 * 0.6 / sqr(6) = 0.0333m/s.
But with this acceleration it over shoots in the negative direction by 500mm.
Take a look at the PLC Open motion function blocks, for example the MC_MoveRelative and the MC_MoveContinuesRelative block:
(Beckhoff documentation)
As Sergey already stated you can use those blocks to create a motion profile by entering all the parameters you need and integrating the blocks in a step chain.
Suppose I have an object A at position x = 0 and object B at position x = 16.
Suppose A have this code:
public class Move : MonoBehaviour
{
float speed = 0.04f;
Update()
{
transform.Translate(speed, 0, 0);
}
}
My question is: how to evaluate how many seconds (precisely) will it take for A to collide with B?
If I apply the formula S = S0 + vt, it won't work correctly, because I don't know how to measure how many frames it will pass in a second to exactly measure what speed is.
First of all you shouldn't do that. Your code is currently framerate-dependent so the object moves faster if you have a higher framerate!
Rather use Time.deltaTime
This property provides the time between the current and previous frame.
to convert your speed from Unity Units / frame into Unity Units / second
transform.Translate(speed * Time.deltaTime, 0, 0);
this means the object now moves with 0.04 Unity Units / second (framerate-independent).
Then I would say the required time in seconds is simply
var distance = Mathf.Abs(transform.position.x - objectB.transform.position.x);
var timeInSeconds = distance / speed;
Though .. this obviously still assumes by "collide" you mean at the same position (at least on the X axis) .. you could also take their widths into account since their surfaces will collide earlier than this ;)
var distance = Mathf.Abs(transform.position.x - objectB.transform.position.x) - (objectAWidth + objectBWidth);
var timeInSeconds = distance / speed;
My rocket's rigidbody velocity is Vector2(0,100) when I call a function. How can I calculate the world coordinate (enpoint) when the velocity reaches 0?
Gravity should be included in the formula.
Thanks!
It sounds like you want the integral of the velocity function, which should provide the total distance respective to time.
Your velocity is going to be v = (100 - ('t'ime * 'g'ravity)). We can solve for time like t = (-v + 100)/g -> t = (0 + 100)/g = 100/g. So you should reach zero velocity at t = 100/g (assuming all the same units).
The integral of your velocity will give you distance traveled. An integral calculator is here: http://www.integral-calculator.com/
The integral function of your velocity is 100t - (g*t^2)/2
From zero to a particular time t, you can just plug and play. So for example, if for a particular gravity you reach zero velocity at t = 10 seconds, you will have traveled (100 * 10) - ((g * 10^2)/2) distance. (so for gravity 9, you would get 1000 - (9 * 100)/2 = 550 units
Edit: To be clear - first you want to calculate how long it takes to get to velocity zero at a particular starting velocity and gravity:
t = vStart/g
Then plug that time value into the integral function above:
distance = (vStart * t) - ((g * t^2)/2)
(or clearly you could turn it into one function by replacing t with vStart/g in the second function, but if I were coding I would definitely calculate them in two steps to provide a sanity check in case my units were wrong)
Trying to programatically set the force based on the distance of the selected object, and another static object.
To understand this better I am making a golf game, I have forced being applied to ball already done but I am manually setting the force at this point. Right now I am trying to build some pseudo-code for how I can accomplish this. I do not have a lot of experience with physics so anything will help here. But basically I have a golfer who selects an area that he would like to hit it to. So once selected, I will grab the location of the selection, obviously find the difference via (selected.transform.position - golfer.transform.position) but now I am a little stuck on what to do next. How can I find the force needed to get to the selected location?
here's some current code in case it helps
var target : Transform;
var speed : float;
var force : float;
var angle = 50;
var i = 1;
function FixedUpdate()
{
if (target == null)
target = GameObject.FindWithTag("Hole").transform;
}
function Hit()
{
var torque = Vector3(Input.GetAxis("Vertical"), 0, -Input.GetAxis("Horizontal"));
var targetRotation = Quaternion.LookRotation (target.position-transform.position,Vector3.forward);
transform.rotation = Quaternion.Slerp(transform.rotation,targetRotation,8);
transform.eulerAngles.x = -angle;
rigidbody.AddTorque(torque.normalized*speed);
rigidbody.AddForceAtPosition (transform.forward * speed * force,target.position, ForceMode.VelocityChange );
}
You will need a few things.
Angle of Force theta
Mass of object m
On the x-axis:
Acceleration a
Initial velocity vi
Final velocity vf
Distance d
Time to travel t
On the y-axis:
Acceleration a = gravity
Initial velocity vi_y
Final velocity vf_y
Height traveled h
Then use the equations for Kinematics and F=ma to find the force.
Your goal is to combine what you know, mass of object, distance, etc. and apply the equations of kinematics to find the acceleration needed on the x-axis. Then you will plug in that acceleration and the mass to F=ma to find the Force.
I have 1000+ row Sine Wave data which changes with time and I want to visualize it with Processing language. My aim is to create an animation which will draw a Sine Wave with time starting from the middle of the rectangular [height/2]. I also want to show only the 1 second periods of that wave. I mean after 1 second, first coordinate should dissappear, and so forth.
How can I achieve that ?
Thanks
Sample Data :
TIME X Y
0.1333 0 0
0.2666 0.1 0.0999983333
0.3999 0.2 0.1999866669
0.5332 0.3 0.299955002
0.6665 0.4 0.3998933419
0.7998 0.5 0.4997916927
0.9331 0.6 0.5996400648
1.0664 0.7 0.6994284734
The way you'd achieve that is to split this project into tasks:
load & parse data
update time and render data
To make sure part 1 goes smoothly it's probably best to make sure your data is easy to parse first. The sample data looks like a table/spreadsheet, but it's not formatted with a standard separator(e.g. comma or tab). You can fiddle things when you parse, but I recommend using clean data first, for example, if you plan on using space as a separator:
TIME X Y
0.1333 0.0 0
0.2666 0.1 0.0999983333
0.3999 0.2 0.1999866669
0.5332 0.3 0.299955002
0.6665 0.4 0.3998933419
0.7998 0.5 0.4997916927
0.9331 0.6 0.5996400648
1.0664 0.7 0.6994284734
Once that's done, you can use loadStrings() to load the data and split() to break a row into 3 elements which can be converted from string to float.
Once you've got value to use, you can store them. You can either create three arrays, each holding a field from the loaded data(one for all the X values, one for all the Y values and one for all the time values) or you can cheat and use a single array of PVector objects. Although PVector is meant for 3D math/linear algebra, you have 2D coordinates, so you can store time as 3rd 'dimension'/component.
Part two revolves mostly around updating based on time, and this is where millis() comes in handy. You can check the amount of time passed between updates and if it's greater than a certain (delay) value, it's time for another update (of the frame/data row index).
The last part you need to worry about is rendering the data on screen. Luckily in your sample data the coordinates are normalized(between 0.0 and 1.0) which makes easy to map to the sketch dimensions(by using simple multiplication). Otherwise the map() function comes in handy.
Here's a sketch to illustrate the above, data.csv is a text file containing the formatted sample data from above:
PVector[] frames;//keep track of the frame data(position(x,y) and time(store in PVector's z property))
int currentFrame = 0,totalFrames;//keep track of the current frame and total frames from the csv
int now, delay = 1000;//keep track of time and a delay to update frames
void setup(){
//handle data
String[] rows = loadStrings("data.csv");//load data
totalFrames = rows.length-1;//get total number of lines (-1 = sans the header)
frames = new PVector[totalFrames];//initialize/allocate frame data array
for(int i = 1 ; i <= totalFrames; i++){//start parsing data(from 1, skip header)
String[] frame = rows[i].split(" ");//chop each row into 3 strings(time,x,y)
frames[i-1] = new PVector(float(frame[1]),float(frame[2]),float(frame[0]));//parse each row(not i-1 to get back to 0 index) and how the PVector's initialized 1,2,0 (x,y,time)
}
now = millis();//initialize this to keep track of time
//render setup, up to you
size(400,400);smooth();fill(0);strokeWeight(15);
}
void draw(){
//update
if(millis() - now >= delay){//if the amount of time between the current millis() and the last time we updated is greater than the delay (i.e. every 'delay' ms)
currentFrame++;//update the frame index
if(currentFrame >= totalFrames) currentFrame = 0;//reset to 0 if we reached the end
now = millis();//finally update our timer/stop-watch variable
}
PVector frame = frames[currentFrame];//get the data for the current frame
//render
background(255);
point(frame.x * width,frame.y * height);//draw
text("frame index: " + currentFrame + " data: " + frame,mouseX,mouseY);
}
There are a couple of extra notes needed:
You mentioned moving to the next coordinate after 1 second. From what I can see in your sample data there are 8 updates per second, so 1000/8 would probably work better. It's up to you how you handle timing though.
I assume your full set includes data for a sine wave movement. I've mapped to the full coordinates, but in the render part of the draw() loop you can map however you like(e.g. including a height/2 offset, etc.). Also if you're not familiar with sine waves, have a look at these Processing resources: Daniel Shiffman's SineWave sample, Ira Greenberg's trig tutorial.