Bug with Ti not disabled with zero setting

Duncan_Ritchie · April 2, 2020, 10:09pm

HI

The UI says setting Ti to zero will disable it but it doesn’t. It works with Td.

Cheers

Elco · April 2, 2020, 10:42pm

Thanks for reporting.
Looks like setting Ti to zero prevents the integral from accumulating, but did not reset it.

Already pushed a bug fix, will include it in the next release.

You can manually reset the integral or set it to any desired value by clicking ‘I’.

Edit: tried it. Actually you can only do that when Ti is not zero, to prevent divide by zero here:

github.com

BrewBlox/brewblox-firmware/blob/develop/lib/src/Pid.cpp#L141


    if (arg != 0) {
        // scale integral history so integral action doesn't change
        m_integral = m_integral * safe_elastic_fixed_point<15, 15>(cnl::quotient(m_kp, arg));
    }
    m_kp = arg;
}


void
Pid::ti(const uint16_t& arg)
{
    if (m_ti != 0) {
        // scale integral history so integral action doesn't change
        m_integral = cnl::wrap<integral_t>((int64_t(cnl::unwrap(m_integral)) * arg) / m_ti);
    }
    m_ti = arg;
}


void
Pid::setIntegral(const out_t& newIntegratorPart)
{
    if (m_kp == 0) {

Duncan_Ritchie · April 3, 2020, 12:51am

Awesome thanks for the quick response.