Send to closest unoccupied space

[axe34]

Hi

I'm undertaking a mechanical project whereby I wish to send an object (crate etc.) to an array of shelf spaces. Each space will have a button, so that when the object is put into the space, the button will be pressed by the weight of the object.

So, I want to start from having all shelves free, press a 'send' button and the object will be taken to the closest space, the next object to the 2nd closest space etc. I then want to retrieve an object from any space too. The idea is that I want to have one 'send' button (sends to nearest space) and I will use a potentiometer and button to retrieve from the desired space I select.

Does anyone have an idea where to begin? Has anyone done anything similar? I'm using CCS compiler and C code.Thanks

 

[berkeman]

Hi

I'm undertaking a mechanical project whereby I wish to send an object (crate etc.) to an array of shelf spaces. Each space will have a button, so that when the object is put into the space, the button will be pressed by the weight of the object.

So, I want to start from having all shelves free, press a 'send' button and the object will be taken to the closest space, the next object to the 2nd closest space etc. I then want to retrieve an object from any space too. The idea is that I want to have one 'send' button (sends to nearest space) and I will use a potentiometer and button to retrieve from the desired space I select.

Does anyone have an idea where to begin? Has anyone done anything similar? I'm using CCS compiler and C code.Thanks

Sounds like a school project. What are you going to use for the mechanical actuators, transport mechanism, switch sensors, etc.?

 

[axe34]

No, it's not a ''school project''. The actuators are irrelevant to this question, but they are a combi of DC's and steppers. Switches are micro switches.

Oh how I love the unhelpful responses on this forum. I'm sure if it was a simple ''school'' project then you'd give me a simple ''school'' answer, wouldn't you?
:)

 

[berkeman]

No, it's not a ''school project''. The actuators are irrelevant to this question, but they are a combi of DC's and steppers. Switches are micro switches.

Oh how I love the unhelpful responses on this forum. I'm sure if it was a simple ''school'' project then you'd give me a simple ''school'' answer, wouldn't you?
:)

Not sure why you're offended, but whatever. First, using a potentiometer to select which bin to fetch from sounds very much like a low-end intro schoolwork project. And I asked for clarification, because as you know, schoolwork questions go in the Homework Help forums, and you need to show your work before we can offer tutorial assistance.

Anyway, I don't see how you can say that the mechanical part of this doesn't matter. Is this just a paper design? Or is it just the programming part that you are going to do, with stubs for the parts that would be your I/O routines? How many I/Os would you have if this were a real system?

 

[jim mcnamara]

Berkeman is correct. But, what you want is a linear search algorithm. You are working in an embedded system - like a microcontroller, so you have limited memory. I would consider a bit-array, where bit=1 == full, bit=0 == empty. This will not work if there are implied differences in contents of the bin.
Use 16 bit words, uint16_t, you need to map each bin to one and only one bit in the array.

Note: I got the 16 bit suggestion from reading what CCS supports, you should know that cold. I would have used whatever the native word size for the microcontroller is otherwise.

See: https://graphics.stanford.edu/~seander/bithacks.html

// return -1 all bins are full, else return bin #
int ff_empty(uint16_t *arr, int arrlen)
{
   int i=0;
   int j=0;
   for(i=0; i<arrlen; i++)
   {
       if( arr[i]< 0xffff)
         return (i *16 + ffs( arr[i] ^ 0xffff) ); 
   }
   return -1;
}

If this does not appear to be simple, get some more help. Bit hack every 'algorithm' this way - find first empty, find first full, mark bin empty, mark bin full. Also this does not handle the issues surrounding the number of bins not evenly divisible by 16.