Position determination for valves

A position sensor for a valve, the position sensor comprising:

• a rotary encoder;
• and
• a controller;
• wherein the rotary encoder comprises:
• a rotatable code plate for coupling to a valve;
• and
• an optical detector module comprising one or more optical detectors, wherein each optical detector is aligned with a respective concentric circular arc around the rotatable code plate and is configured to receive light passing through the code plate when the code plate is in any of a first set of angular positions and to be blocked by the code plate from receiving light through the code plate when the code plate is in any of a second set of angular positions,
• wherein the controller comprises:
• a memory;
• and
• control logic, wherein the control logic is configured, when in a first state, to:
• receive a first set of time-varying output signals from the optical detector module as the code plate rotates during a first time period;
• process the first set of time-varying output signals to determine, from the first set of time-varying output signals, a first position of the rotatable code plate;
• and
• store data representative of the first position of the rotatable code plate in the memory, and
• wherein the control logic is configured, when in a second state, to:
• receive a second set of time-varying output signals from the optical detector module as the code plate rotates during a second time period, after the first time period;
• and
• process i) the stored data representative of the first position of the rotatable code plate and ii) the second set of time-varying output signals, to determine, from the stored data and from the second set of time-varying output signals, a second position of the rotatable code plate;
• wherein the control logic is configured, when in the second state, to maintain a value in the memory representative of a current position of the code plate, and is configured to detect changes in the second set of output signals and to advance the stored current position by one increment around a cycle of position values in response to each change of state in the second set of time-varying output signals.

A position sensor for a valve, the position sensor comprising:

• a rotary encoder;
• and
• a controller;
• wherein the rotary encoder comprises:
• a rotatable code plate for coupling to a valve;
• and
• an optical detector module comprising one or more optical detectors, wherein each optical detector is aligned with a respective concentric circular arc around the rotatable code plate and is configured to receive light passing through the code plate when the code plate is in any of a first set of angular positions and to be blocked by the code plate from receiving light through the code plate when the code plate is in any of a second set of angular positions,
• wherein the controller comprises:
• a memory;
• and
• control logic, wherein the control logic is configured, when in a first state, to:
• receive a first set of time-varying output signals from the optical detector module as the code plate rotates during a first time period;
• process the first set of time-varying output signals to determine, from the first set of time-varying output signals, a first position of the rotatable code plate;
• and
• store data representative of the first position of the rotatable code plate in the memory, and
• wherein the control logic is configured, when in a second state, to:
• receive a second set of time-varying output signals from the optical detector module as the code plate rotates during a second time period, after the first time period;
• and
• process i) the stored data representative of the first position of the rotatable code plate and ii) the second set of time-varying output signals, to determine, from the stored data and from the second set of time-varying output signals, a second position of the rotatable code plate;
• wherein the control logic is configured, when in the second state, to received data representative of a target position for the code plate, and to process the received data and data representative of a current position of the code plate to determine whether to instruct a valve actuator to rotate clockwise or counterclockwise such that the code plate will rotate through a maximum of 180 degrees to reach the target position.