Is it possible to directly use rpm value from esc telemetry instead of mounting a external rpm sensor? As I am using a small and compact helicopter frame and two BLHeli_32 ESC for main motor and tail motor, directly reading rpm from ESC can make room for rangefinders and optical flow sensor.
Yes, of course it is, but you need a telemetry capable ESC. With a compatible ESC FW, and a ArduCopter 4.1.0-beta5 for best results. After that they need to be correctly connected, and configured.
can that be assigned to RPM1. That is the only RPM instance that the tradheli code uses for the internal rotor speed governor.
I know the OP said they didn’t want to use an external sensor, but I’m presuming they are referring to either magnetic or optical sensors, there is an alternative that might be quite interesting for them. hobbywing do a very inexpensive little sensor that conveniently clips into the servo rail on a pixhawk type board, and has two wires that tap into any of the three wires going to the motor, it comprises an opto-isolator, and can work with upto 16s ESC setups, and has a wide operating voltage from the servo rail of 3.2-8.4v, futhermore it’s toaty, and weighs next to nothing, heres the specs:
- Size: 23mm(L)*10mm(w)*2mm(H)
- Weight: 6g (Input and output wires are included)
- Working voltage: 3.5V to 8.4V(1S to 2S Lipo)
- Current: 1 to 5mA
- Voltage range of the motor wires: 2 to 16S Lipo
- RPM range (for 2 poles brushless motor): 1000rpm to 300000rpm
- Working temperature: 0 to 50 Celsius degree or 32 to 122 Fahrenheit degree
And a link to buy it from: