Height control system based on timer (probably using hydraulic)

Dear All,

I'm new here, and having gone through some of very interesting and creative posts led me to post my question here.

I need to develop a tool to control the height (basically angle) of air flow gates for the poultry shed. The gates have to be at an angle at night (to avoid cold wind in) and then as the sun rises the gate slowly open up (with a programable calculated degree) throughout the day and then at night they gate close back. If possible the big waoo factor would be, if i would be able to alter/program the hourly angle based on summer and winter separately, that would make my life a lot easier.

I've been trying to find a solution but could not find a single product that can help me fix the issue, right now this is being done on manual basis and i want to automate it.
Bad weather here this morning, so a good opportunity to write all this out.

The control of dampers is fairly common in automation, however, this not likely a $100 job; more likely hundreds or thousands of dollars, all depending . . .

If the air control is multiple louvers on a damper then starting at the tail end of the control loop, each 'set' of damper gates needs an actuator. Actuators can be linear or rotary. Rotary actuators typically rotate 90° to mimic the action of damper louvers, 0° = closed, 90° = open, 45° = half way open. The actuator's output shaft might be direct connected to a rotating shaft on the damper or a crankarm can be mounted on the actuator shaft which is then connected to the damper shaft with linkage - ball joints and a rod. Electric motor driven actuators are common.

If the air control is solid door/gates then either a mechanical linkage scheme using a rotary actuator or a direct connection to a linear actuator drives the door/gates.

The actuator needs power and a control signal. The most common control signal is 4-20mA in the industrial world, but there are control schemes that use an open signal and a separate close signal. Caveat Emptor: your controller's output signal must match whatever the actuator's control signal is (recent thread on another forum revealed that was one guy's problem, they didn't match).

Rotary electric actuators are sold by torque rating, type of input drive signal, and duty cycle (among other features, like housing). The lower cost 20% duty cycle electric actuators should do the trick for door/gate control. If the actuator is exposed to non-office like conditions, then seriously consider an actuator rated NEMA4 (weather proof to water intrusion). But even NEMA4 does not mean it works when frozen by ice.

At the front end of the control loop is what you're using to control the gates.

You mentioned two things: time of day and the reason for control - to make sure it doesn't get cold. Coming from the temperature control world, I think it's easier to control to temperature for a couple reasons.

The gate position is not likely to be the same at the same time of day on February 2nd and it is on July 2nd. Manually, the adjuster guy makes that decision, but unless your time-of-day control scheme takes into account the date, the time-of-day controller doesn't it into account.

Another reason is that the temperature on any given day of the year is not likely to be the same as the day before or the day after. Again, it's obvious to the manual adjuster, but not obvious to a date-and-time-of-day controller what the weather is.

Automated temperature control takes into account what temperature you are trying to maintain, like the thermostat in your house. And like the thermostat in your house could even have a 'setback' setpoint if the temperature setpoint (desired temperature) at night is different than the daytime setpoint.

Your choice, but if you want to control temperature then controlling to a measured temperature in the poultry barn is likely to give you better results than date-and-time-of-day control.

The front end of temperature control is a temperature sensor. Choice is either a thermocouple or an RTD. Avoid thermistor sensors. Either can be had in an industrial version with a stainless steel sheath that can hang at some point (not exposed to sun or blower air) and connected to the controller with wires (unlike your home thermostat which has the sensor embedded in the thermostat housing). Main difference is that the thermocouple needs to be connected to the controller with the same type of thermocouple wire (Thermocouples have different types, I'd suggest Type T). Using ordinary copper wire for the lead wire connection results in thermocouple measurement error. A 3-wire RTD uses copper wire extension leads, but many of the inexpensive controllers suitable for this kind of control use only 2 wires resulting in a measurement offset error, which can be corrected but the correction is seldom done.

There are lots of (relatively) inexpensive temperature controllers with a 4-20mA output. The issue is that the controller comes out of the box incapable ofcontrolling, it need to be configured with maybe a dozen critical settings, one of which is what type sensor is being used. Another is control action, which depends on whether the gates open or close to drive the temperature up (or down). And the one that gets the most play on fora like this is the control scheme: PID, whose 3 PID settings/parameters/terms need to be 'tuned' to the conditions. That takes someone with an understanding of what PID does and how it does it.

If the date-time-of-day makes more sense then you need a more sophisticated controller that can reference a table of setpoints, depending on the date and time-of-day. You need to provide the table, position by by the hour and date or month or season or whatever category makes sense.

There are controllers called PLC's that are more flexible and more programmable than 'simple' temperature controllers, with the trade-off being that you have to know how to program them. Introductory programming is a PLC101 course at a local community college. A date/time-of-day controller would probably use a PLC

Or, you could put the actuators on the gates and control them manually from a remote location with a knob or a dial, avoiding the automation involved in a temperature controller or PLC, but with convenience or remote positioning, since human experience knows the exact door position best.

Final note, my neighbor raised feeder pigs and the biggest problem with his relay/timer logic controlled feeding system was corrosion, both mechanical and electrical. I don't know how conditions in a poultry barn compares to pigs, but be aware that corrosion makes things not work right. An actuator can't bang the door with a hammer if it sticks, like the human adjuster can, and a stuck actuator motor can burn out.

There are companies that do this kind of design and implementation for a living. An ambitious heating refrigeration firm might tackle it. Or uou might inquire at a local factory as to who does their 'controls'. Some places outsource the controls work, others employ their own people, but even employees are likely to know firms who do controls projects.
Control Engineers are happy to work with hydraulics but tend to be
electrically minded.
On that point could the air flow gates be inched open/closed electrically.

Siemens Logo! is a fairly cheap PLC with realtime clock which is easily
programmed. It also comes with a display so you can change parameters online.

I would suggest adding a temperature sensor to operate rather than time of day.