Method for determining amplitude of stick-slip on a valve assembly and implementation thereof

An apparatus, comprising:

• a processor configured to access a memory that has one or more executable instructions stored thereon, the executable instruction comprising one or more instructions that configure the apparatus for,
• calculating a metric from set point data and position data for a valve assembly;
• using the metric to identify a cycling condition on the valve assembly;
• selecting a process in response to the cycling condition;
• using the process to identify a contributing factor to the cycling condition;
• setting the contributing factor according to a relationship between a first amplitude of the position data and a second amplitude of the position data, wherein one of the first amplitude and the second amplitude indicates that the position data forms a square wave;
• and
• generating an alert in response to the contributing factor, the alert selected from,
• instructions to change process parameters, and
• instructions to perform maintenance on the valve assembly,
• wherein the metric corresponds to a ratio of a first p-norm function to a second p-norm function that use the position data and the set point data, respectively.

A valve assembly, comprising

• a seat;
• a closure member that moves relative to the seat,
• an actuator coupled with the closure member;
• and
• a valve positioner coupled with the actuator, the valve positioner configured to,
• calculate a metric from set point data and position data;
• use the metric to identify a cycling condition of the closure member;
• select a process in response to the cycling condition;
• use the process to identify a contributing factor to the cycling condition;
• set the contributing factor according to a relationship between a first amplitude of the position data and a second amplitude of the position data, wherein one of the first amplitude and the second amplitude indicates that the position data forms a square wave;
• and
• generate an alert in response to the contributing factor, the alert selected from,
• instructions to change process parameters, and
• instructions to perform maintenance,
• wherein the metric corresponds to a ratio of a first p-norm function to a second p-norm function that use the position data and the set point data, respectively.