Methods and apparatus to detect and/or recover from failures in valve control devices

A non-transitory computer readable medium comprising instructions that, when executed, cause a machine to at least:

• provide a digital input signal to a first converter at a first point in time, the first converter corresponding to one of a supply converter or an exhaust converter, the supply converter to control actuation of a supply relay to deliver pressurized fluid to an actuator operatively coupled to a valve in a process control system, the exhaust converter to control actuation of an exhaust relay to exhaust the pressurized fluid from the actuator, the digital input signal to trigger application of a current to the first converter to open the first converter;
• determine a difference in at least one of a pressure in the actuator or a position of a flow control member in the valve over a period of time following the first point in time;
• and
• detect a failure of at least one of the supply converter, the exhaust converter, the supply relay, or the exhaust relay when the difference satisfies a failure threshold.

A method comprising:

• providing a digital input signal to a first converter at a first point in time, the first converter corresponding to one of a supply converter or an exhaust converter, the supply converter to control actuation of a supply relay to deliver pressurized fluid to an actuator operatively coupled to a valve in a process control system, the exhaust converter to control actuation of an exhaust relay to exhaust the pressurized fluid from the actuator, the digital input signal to trigger application of a current to the first converter to open the first converter;
• determining a difference in at least one of a pressure in the actuator or a position of a flow control member in the valve over a period of time following the first point in time;
• and
• detecting a failure of at least one of the supply converter, the exhaust converter, the supply relay, or the exhaust relay when the difference satisfies a failure threshold.