From a909abbdd16d395a32a799a8689435c639c4f973 Mon Sep 17 00:00:00 2001 From: Lucien Renaud Date: Thu, 26 May 2022 19:27:44 +0200 Subject: [PATCH] Update 'README.md' Fix the image link --- README.md | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/README.md b/README.md index 6b9782f..5d0f47c 100644 --- a/README.md +++ b/README.md @@ -2,8 +2,8 @@ The aim of this project is to be able to use the 3-axis DJI gimbal with a custom open source controller like [SimpleFOC](https://docs.simplefoc.com/). This high quality gimbal is very tiny and easy to find as a replacement part which makes it very suitable for DIY projects. - - + + ## Pinout identification The Gimbal is composed of a flex PCB with a main connector and 3 smaller for each motor. The main end connector is a 40-pin mezzanine board to board connectors. In order to work easily I have designed a breakout board which open to a 2.54" header. (Kicad folder) @@ -13,7 +13,7 @@ Here is the strategy I followed to find the pinout: 2. Group remaining pins by motor With the multimeter find all the pins connected to the motor connector. (Reapeat 3 times for the other connectors) - + ### Open-loop control @@ -31,7 +31,7 @@ Connected directly to a MCU (here a STM32 Nucleo F401RE) and with the Simple FOC ### 1. Setup Each motor is composed of two ratiometric linear hall sensors. (Texas Instrument DRV5053 Analog-Bipolar Hall Effect Sensor) They are placed at around 120º from each other (eyes measured) and measure the magnetic field of the rotor. - + Ratiometric means that the output signal is proportional to the voltage supply to the sensor. In this setup, with 5V supply, the output measured is between 520mV and 1.5V, so a 1V amplitude signal. @@ -40,7 +40,7 @@ Ratiometric means that the output signal is proportional to the voltage supply t These oscilloscope traces are the sensor output when rotating the rotor forth and back. (a bit less than 180º on the 3rd motor) The channel 0 (Yellow) is the Hall 1 and the Channel 1 (Green) is the Hall 2 - + We can see that in the first movement (positive rotation), the green is out of phase of π/2.` @@ -102,4 +102,4 @@ To achive position control it is necessary to have first, a velocity controller However, the motors of the gimbal have hard stop and can only rotate of around a half turn. It was so necessary to remove these mecanical stops. I drilled with a 1.6mm drill the two little holes to remove it. Then the motor was able to rotate freely and PID can be tuned. - +