Modify a normal servo to wench servo on RC sail boat.Part1

 A RC wench servo required several turns, since GWS died, it's not easy to get one. Thunder tiger also have such servo before, but not any more.


My first idea is to use step motor, with limit switch on belt(served to get first ), like the rail system in 3D printer. These ULN2003 + 28BYJ-48 5V is  very cheap, but after testing, the torque does not seems promising. 

The motor is geared, so the holding torque is quite good, but the motor current is quite low, so the turning torque is low, and can be stopped by hand. with SW control with 2 phases engage, is still the same.

The multi turn servo has a set of reduction gear on the VR, I came across on web with these toy gear, with 0.5M, I decided to make a reduction gear from out side.



I took a metal gear servo, the gear to attached servo horn has a internal M3 threat, I put a very long M3 screw from inside, the the first 15T toy gear is fixed on it.
2nd gear is a 50-10 gear, the the last one(50T) is attached on VR.
this give me a 7 turns servo. it works! The torque is good, the down side is that, if you turn the servo, the dead band is about 5 degree. But it should work  on a sail boat wench.






I made it as a linear servo, but the death band is large, also, it's difficult to keep the tesnsion.




2024/4/27

This is an example of making a multi turns servo for genoa:


The idea is to use a 10 turns VR, which is quite large.



Here comes an idea of using small multi turn VR:
First idea is to link this to final gear of servo, But, the turn knob is too small, not easy to do it.
But, there is another version of this:

The shaft is about 4mm, which seems possible to attached to some thing.
By using GT2 belt and pully(easy to find with 3D printer shop) it seems possible to make a linear servo system.




I order few piece of VR with 4mm shaft, I still have few 450 RC heli parts on hand, after measurement, I found the mod Nr and the tangent circuit's diameter.


3D printed stand and have the gear and VR mounted, the belt pully is about 11teeth. 


The belt used in a 450 heli is a 397XML:

XML:
397MXL397806.7
397teeth, 806.7mm is length, pitch is XML is 2.032mm





If I use 11 teeth pully as well as, 
{806.7-(11*2.032)} so I have about 39cm of length, 
Travel:
since the VR is about 20turns, so it depends on the pully it's connected to, with 11T I will have about 22mm*20=440mm, but most of servo controller board will not use whole VR, unless you design our own.

I refer to few genius designs on web:





This is what I came up with:

The servo I used is a very slow one, and the PID need to be tuned, since it has some overshoot...












留言

張貼留言

這個網誌中的熱門文章

Heltec ESP32+OLED+Lora, hardware testing

圖片
you can easily find some good boards from china, but most of them lack of accurate document... Hrere is an example; https://hackaday.io/project/26991-esp32-board-wifi-lora-32 the board looks good with lora and a 128x64 OLED, but the IIC and reset connection is important, since pin can be muxing easily, so every board could be different. pinMode(16,OUTPUT);  digitalWrite(16, LOW); // set GPIO16 low to reset OLED  delay(50);  digitalWrite(16, HIGH); // while OLED is running, must set GPIO16 to high  and, if needed, edit your Wire.begin() to Wire.begin(4,15); (4 = SDA 15 SCL)  i tested it with the Adafruit SSD1306 and the Acrobotics SSD1306 Librarys  both work.  Display size is 128x64 There are discussions on these boards on TＴＮ as a LORA node..or maybee single ch gateway? Heltec has a git :  https://github.com/Heltec-Aaron-Lee And there is another copy call TTGO https://de.aliexpress.com/item/TTGO-LORA32-868-915-Mhz-S...
閱讀完整內容

micro SD card for ESP32, on lolin32 with OLED and heltec 32 lora oled

圖片
I have purchased 2 micro SD card holder for my esp project. First I would like to test with heltec esp32 lora oled module. this module uses: sck=05 MISO=19 MOSI=27 SS(lora)=18, then I assigned 21 for sd SS and there is a lib in esp32-arduino, which use SS default at 5 I took the example and use SD.begin(21), but I alway get the error: entry 0x40078a9c Card Mount Failed But I do saw once that it read out the sd card type and volume. Not sure it's the issue of lora sd card swithing, or it just can't work. The other esp32 card I have is an wemos esp32 oled, it did not leave me too much pins, I need to find out how to connect sd to it. But I have wemos D1 mini esp8266 on hand, and connect it as:  * The WeMos Micro SD Shield uses:  * D5, D6, D7, D8, 3V3 and G  *  * The shield uses SPI bus pins:  * D5 = CLK  * D6 = MISO  * D7 = MOSI  * D8 = CS It's not working with the example in the arduino IDE 1.8.5, which m...
閱讀完整內容

AIS0. understanding AIS NMEA 0183: How it's coded

For my boat tracking system, I found out that using AIS format seems to be a good idea, at least I don't have to worry about how to present boat data, since there are already plenty things for do this on mobile phone or PC. Here is what I read: http://catb.org/gpsd/AIVDM.html Looking into AIS NMEA0183, it has much more application then I think. Such as MOB device, epir, aid to navigation device...etc, all are included. it use the first few char to indicate the function: Table 1. AIS talker IDs !AB NMEA 4.0 Base AIS station !AD MMEA 4.0 Dependent AIS Base Station !AI Mobile AIS station !AN NMEA 4.0 Aid to Navigation AIS station !AR NMEA 4.0 AIS Receiving Station !AS NMEA 4.0 Limited Base Station !AT NMEA 4.0 AIS Transmitting Station !AX NMEA 4.0 Repeater AIS station !BS Base AIS station (deprecated in NMEA 4.0) !SA NMEA 4.0 Physical Shore AIS Station It can also be used between device on boat for message communication, AIVDO The...
閱讀完整內容