On Jan 24 2017 6:29 AM, andy pugh wrote:
> On 24 January 2017 at 00:06, John Thornton <j...@gnipsel.com> wrote:
>> if(enable){
>> float min_velocity = requested_vel
>> -(requested_vel*(1/velocity_tol));
>> if(current_vel > 0 && current_vel >=
>> min_velocity){vel_status = 1;}
>> else {vel_status = 0;}
>>
>> if(torch_on && arc_ok && vel_status){ // allow correction
>> //if(volts_requested - volts > volts_limit){
>> // volts = volts_requested - volts_limit;
>> //}
>> //else if(volts_requested + volts > volts_limit){
>> // volts = volts_requested +volts_limit;
>> //}
>> if (abs(volts_requested - volts) > voltage_tol) {
>> offset += (volts_requested - volts) * p_gain;
>> }
>> last_z_in = 0;
>> }
>
>
> The code for an actual PID is pretty simple.
>
> static double olderror, iterm
> if(torch_on && arc_ok && vel_status){ // allow correction
> error = (volts_requested - volts)
> dterm = (error - olderrer) * Dgain
> olderror = error
> iterm += error * Igain
> pterm = error * Pgain
> if (absf(error) > deadband){
> offset += pterm + iterm + dterm
> }
>
> Is close. You probably need to initialise olderror intelligently, to
> avoid a single-cycle crazy value.
I am not completely convinced that the offset calculation in case of
"absf(error) > deadband" is sufficient. The various terms might still
give you an unreasonable offset. Might need to clamp that as well, but
I am not fully sure what that would imply.
EBo --
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