Think of this:

1.- When creating a new PING order, read the 24HMax and the 24HMin and calculate the median price Mpn = (24HMax + 24HMin) / 2 and store that value.

2.- Repeat the process at the next PING order creation -> Mpn+1

3. Calculate the % variation of the median price since last PING.  Var% = (Mpn+1 - Mpn) / Mpn.

4.- Use that variation Var% to adjust the price limit upwards or downwards.

Not that difficult. A couple of hours.  

Of course you could make it just an option.