How to set up ms4525do?

ArduPlane
1

I am using “PX4 Airspeed v1.3” from HolyBro.

On a previous flight, I almost lost the plane due to stalling cause airspeed.

I have a few questions about parameter settings.

  1. ARSPD_PIN is 15 (default, 4.4.2)
    But my value is 65. Does this make a difference?

  2. ARSPD_RATIO is 2 (default, 4.4.2)
    But my value is 2.9 Likewise, is this wrong?

  3. ARSPD_OPTIONS is 11 (default, 4.4.2)
    mine is 0, is wrong?

as

Other than that, there is no difference in the values ​​of arspd.

I took the parameters from someone who flew the same plane as me and uploaded them as is.

A bit of a stupid question, but the name of the sensor is px4 Airspeed.

Does this only work properly on px4 and doesn’t work on APM?

What is the appropriate size for the Airspeed tube?

My tube is about 6cm.

Is this too short?

I would appreciate it if you could tell me a really standard, textbook setting method.

Even if I look through Ardu documentation, Discus, etc., the values ​​are different for each, so I don’t know which one is correct.

2

ARSPD_PIN is valid for analog sensors, your sensor does not need to modify it.
ARSPD_RATIO value is not fixed, it is related to the sensor and installation method.

4

“ARSPD_RATIO value is not fixed, it is related to the sensor and installation method.”

So, can you tell me how to determine “ARSPD_RATIO” value?

Additionally, is the arspd pin correct: 65 or 15?

5

Set the initial value of ARSPD_RATIO to 2 and set ARSPD_autocal to 1 (turn on automatic calibration). The ARSPD_RATIO value will be automatically updated during flight. For safety reasons, it may be possible to use FBWA or not use the airspeed sensor as the speed source for the first flight.

6

For digital sensors the arspd pin value is meaningless.

7

Ah thank you for the answer

There was a document on the calibration of ARSPD_RATIO, so I read it carefully.

My sensors are very abnormal right now

Is it okay if I request analysis of the binary log?

8

Sorry for only asking questions.

There weren’t many people who responded, so I had a lot of questions.

What happens if “ARSPD_Ratio” is not set = default, or an incorrect value is entered?

9

Please share your logs.

10

This is the scaling factor. When the scaling factor is too large, the airspeed value obtained by the aircraft will be greater than the actual value. In the end, the aircraft will fly at a very low speed, which may cause insufficient lift and crash.

12

Following this document you can approximate the ARSPD_RATIO from 00000042.BIN. You said that the airspeed readings are overestimated, but they are rather underestimated. TRIM_ARSPD_CM is set at 26.0 m/s, but the aircraft is actually flying at about 29 m/s.

I calculated the approximate ARSPD_RATIO as follows
OLD_RATIO: 2.942466
AVERAGE_AIRSPEED: 26.9
AIRSPEED_INCREASE: 2.4

NEW_RATIO = OLD_RATIO*((AVERAGE_AIRSPEED + AIRSPEED_INCREASE)/AVERAGE_AIRSPEED)^2
= 3.49

If you set ARSPD_AUTOCAL to 1, ARSPD_RATIO will be automatically determined during repeated circuit flight.

I am happy today to see an ideal automatic flight log.

14

A new savior! hello

Thanks for your log analysis.

I guess I was mistaken.

When monitoring the percent of ch3, the throttle servo was so low that it was almost idle. (ch3 percent9=idle)

So I thought this plane had very little power and no speed.

The plane flew at a higher speed than the set speed, and if it stalled, I would need to increase the cruise speed even more.