Mechanical issues and motor troubles

The root of the problem

Yesterday Sibille and I brought the Phyllo structure with the faulty motor (see this post) to the school mechanic, Mr Croullebois. We disassembled the structure, and it turns out the motor shaft goes slightly lower than the motor base, so when we screwed it tight it would scrape against the aluminum plate underneath. 

Mr Croullebois bored a depression in the middle of the plate so we wouldn’t have this problem anymore, and then we reassembled everything with the other motor that we used for tests and knew to be working. The motor that was in the structure spins more freely now, and we managed to make it run, but there is a weird creaking sound from time to time.… Read more

Led’s bare-metal

Today we all brainstormed about the software architecture. 

Since we are still waiting to receive the Hall and optical sensors for the speed feedback aspects, we turned our attention to the rest of the Phyllo.

While Marc and Vlaya worked on how to organise the software for the main board – which they will tell you all about in an upcoming post – Sibille and I looked into the LED-driving PCBs. Their role is simple :

  • Receive color configuration for each LED and control commands via SPI as discussed in this post
  • Configure and control the timers to generate the appropriate PWM signals to light the LEDs

Since these tasks are simple enough, we plan to forego using an OS and instead write bare-metal code.… Read more

First Phyllo “turntable”

Today the school mechanic made great progress on the physical structure of our first Phyllo:

We still have to add the 5V transmission ball bearing right above the top square aluminium plate, as discussed in this post. We haven’t yet received the PVC tube we’ll use to electrically insulate this ball bearing from the shaft, which will be connected to the ground. As soon as we have it assembled we’ll do a test to check the power transmission to the rotating part.

Next we’ll fix a Phyllo shell to the PVC disc using the threaded inserts Vlaya has been working on.… Read more

ESP32 vs STM32

Recently Alexis took the design decision to drop the IrDA idea (see this post) and to instead use an additional ESP32 to communicate between the rotating main board and the bottom PCB (which is in charge of controlling the motor). 

So now the bottom PCB has an ESP32 for the purpose of receiving speed instructions from the main board over Wifi.

Yesterday, I wondered whether we could actually drop the STM32 processor on the bottom PCB and let the ESP32’s CPUs handle everything. We decided that the question was worth investigating, as there really isn’t that much to do on the bottom PCB.… Read more

Taking our new ESCs for a spin

Today we received the AIKON 45A SEFM ESCs we ordered a while ago. Actually that’s a lie: these ESC were received before today, but no one told us until Alexis recalled seeing them when we told him we were waiting for them and pulled them from the top shelf of the cabinet in the back of the classroom. We’ll let it slide, whoever it was, but just this once.

Upon hearing this, Sibille and I immediately decided to put aside for the time being our previous attempts to reflash our most recent motor’s built-in ESC and instead use these new ESCs (which come flashed with BLHeli_S and support DShot out of the box) to control our other motor, the Turnigy Multistar 4225.… Read more

Motor Update

Today, I tried to reflash the built-in ESC of our new motor, EP4108.It runs BLHeli firmware, and we would like to update it in order talk to the ESC via a relatively new protocol, DShot, instead of the age-old PWM control. Short story long, I didn’t manage to do it.

Still, here’s what I tried.

As mentioned in this post, the motor has a 6-pin “flashing port” – except there is no provided connectors and absolutely no instruction on how to reflash the ESC. In fact, we don’t even know what ESC it is. All we know is that it runs some version of the BLHeli open source firmware.… Read more

IR Update

Today Sibille and I made some additional tests with the IR receptors, like we talked about in this recent post.

We used the AGC2 TSOP4856 receptor, as well as a LTE-R38381S-ZF-U emitter, with the same circuit setup for our previous tests described in this post.

The first thing we tested was whether we could overwhelm the receptor’s AGC by exposing it to an IR burst longer than the maximum burst length, which is 1.8ms for our receptor. 

With bursts of 3ms (on) and 100ms gaps (off), the receptor tended to be 10 or 20ms late in reacting to the end of the burst.… Read more

A few bits about motors and ESCs

Hello,

Last Friday we received new motors : the EP4108 320KV with built-in ESC.

We’re particularly interested in those because they have a reflashable integrated BLHeli ESC. It turns out that, starting with BLHeli_S v16.5, which is an open source ESC firmware, a new protocol is supported to replace the old PWM control method : DShot. It’s a serial protocol where speed information is encoded in 16-bit frames, instead of analogically in the duty cycle of a PWM signal.

There are three generations of BLHeli firwmare : BLHeli, BLHeli_S, and BLHeli32 (wich is no longer open source), each with several versions.… Read more

A solid foundation

Last week we met with Alain Croullebois, the go-to guy for mechanical questions at the school. We went to his workshop with the motor we received during the holidays : this Turnigy Multistar 4225-390Kv 16 Poles Multi-Rotor Outrunner. We discussed what the physical structure of the Phyllo could look like.

Here is a global diagram of what we came up with :

The mechanical structure of the whole Phyllo

The Base

For the base of our Phyllo, he suggested stacking two 30cmx30cm aluminium plates 8mm thick, with a separation of 6cm between the two plates maintained by 2cm wide pillars at each corner.… Read more