aqValve Controller
aqValve Controller
A standalone controller for stepper-motor-driven proportional pinch valves. A proportional pinch valve acts as a tunable flow restriction. The aqValve controller drives it to a setpoint from one of four 4–20 mA process inputs. An auto-tune scan characterizes the valve's nonlinear response for fast, tight control.
A proportional pinch valve acts as a tunable flow restriction. Its response is steeply nonlinear; across most of the travel, the tube is barely pinched and the restriction changes very little. However, near the closed position, a small movement sharply increases the restriction. The aqValve controller auto-characterizes the valve and tube with a scan that sweeps the travel and measures the process gain.
Repeatable homing ensures the reliability of the gain schedule. At each power-on, the controller homes to a repeatable reference — using either a Hall sensor or sensorless stall detection — and applies a tunable offset to establish the full-open position. The calibrated full travel is measured from this point, ensuring the same command consistently lands at the same position.
A recorded run engaged control at a 5 psi setpoint, then stepped through 3, 12, and 24 psi and back down through 12 and 2 psi. Pressure, setpoint, and valve position are logged together. On each step the controller feeds forward from the auto-tune's gain curve, moving the valve toward the position it knows produces the new setpoint.
Once settled, control stays steady. Here the loop holds a 5 psi setpoint for 30 minutes: pressure stays within a standard deviation of about 0.009 psi and 0.055 psi peak-to-peak.
Specifications
| Valve | Any stepper-motor-actuated proportional pinch valve (4-wire bipolar) |
|---|---|
| Process control | Per-channel feedforward or gain-scheduled PID to a 4–20 mA setpoint; auto-tune characterization builds the per-channel gain schedule; direct control also available |
| Process inputs | 4× isolated differential 4–20 mA; 24-bit Σ-Δ ADC (~21-bit noise-free); ~1.5 kVrms reinforced isolation; per-channel calibration & units |
| Stepper drive | 256 µsteps/full step; configurable run/hold current (0–1000 mA); configurable speeds, acceleration, and polarity |
| Homing | Hall-sensor and sensorless stall detection; optional auto-home on boot |
| Fieldbus | Modbus RTU over RS-485; half/full duplex; optional internal 120 Ω termination; address 1–247; baud 9,600–1,000,000; FC03/04/06/16/23 |
| Operator interface | Optional 2.8″ color TFT, 240 × 320, projected-capacitive touch (FFC). Headless operation supported. |
| Host interface | USB Type-B, CDC ACM; companion desktop application (configuration not required for normal operation) |
| Power | 24 VDC nominal (18–30 V); reverse-polarity, surge, and over/under-voltage protection; pluggable terminal blocks |
| Persistence | Calibration, PID gains and gain schedules, motion config, and comms settings retained across power cycles |
| Environment | 0 to +60 °C operating; 10–90 % RH non-condensing |
Specifications are subject to change. Contact us for the full datasheet, register reference, and current configuration options.
Request information
Tell us about your application and we'll help you spec the right configuration.
info@aqueductfluidics.com