Hi everyone ! I just come back from holidays and I have received my electronic boards \o/ (made on SeeedStudio)
I also received some cables and the new speakers. I hope I will have time this week to solder the boards.
There are some problems with the top Silkscreen (some letters are missing) but the tracks are good and the quality is also very good. I think the problem comes from the gerber export which gone wrong at some point…
The Raspberry is finally installed ! I just bought the model B+ because it has 4 USB ports, and as I will need 2 for the Wifi and the Webcam, I needed 2 more for the keyboard and mousse for programming the PI 🙂
The model B+ has also 4 mounting holes, which is perfect pour the fixations and it consumes less than the previous model (around 150mA). However I will need to replace the USB and Ethernet connectors which don’t fit in the hood by pin row connectors 😉
I also mounted the mini USB of the STM32 on the top, which is much more easier for programming…
Now I can continue with the final step : The head
I finally finished the integration of the boards inside the body ! It took a little more time than I thought but I wanted the most reliable solution.
For the fixation I will use a carbon fiber support (which I will machine with my CNC). This support will also reinforce the body’s structure 😉 and so far, everything is fitting well inside so I hope it will be the same for the head…
However, I still have to integrate the Raspebby Pi, which will be placed above the STM32.
Rear view with STM32
Top view with STM32
Side cut view
So, the next step is to put the Pi inside and then begin the head design.
I spent the last week on the electronic design. I finished all the boards except the one for the Pi. All the schematics and PCBs are made on Altium Designer.
I also received all the components \o/ so now I can check a last time that all the footprints are correct.
The next step is to send the gerber files of the boards for manufacturing. I’m hesitating between 2 manufacturers : OSH Park and Seeed Studio PCB. I think I will go with OSH Park (previously Batch PCB) because they have a better quality even if they are a bit more expensive than Seeed Studio PCB.
Now I have the boards, I can continue the work on the integration of the boards into the robot and the design of the head.
I didn’t advanced much on the Solidworks Design because I need the size and shape of the PCBs I have to integrate…
Animabot will be composed of 5 PCBs in addition to the Raspberry Pi and the STM32 :
- Power Supply Board
- Li-Ion Charger
- STM32 Board Adapter
- Raspberry Pi Board Adapter
I’m using Altium Designer for the Electronic design, I know that it is a complicated software for the boards I have to do, but I am used to it (I used it previously with my first Hexapod and at my school). For the moment I’m spending a lot of time creating the components and footprints I have… so not very funny…
However, I will create the 4 others PCBs in the next few days to be able to put them into Animabot.
Top PCB View
Front IR view
I also put an Infrared sensor on the front of the robot, so he will be able to avoid falling in the stairways or from a table 😉
I finally finished the legs \o/
Left Side View
Now the legs are done, I can concentrate on the integration of electronic boards inside the body and the design of the head which will integrate :
- Night Vision Led
I also made a special shape for the DC IN connector and the 2 interrupters. I decided to use 2 interrupters in order to be able to disconnect completely the battery from all the electronic (safety reason) and the other is used to power ON the command (Pi and STM32F4)
Zoom power cmd
Zoom In power cmd
I hope you like it 🙂
I reviewed the power distribution of the robot and the system of 2 batteries… and finally, I’m not satisfied… Having 2 batteries inside take more space, it’s not good for the weight balance and it’s more complicated for the electronic because I would have have to design a board with 2 chargers (LTC4008 and MCP73861) and 2 power monitors (LTC2945). It’s not that complicated but designing a charger board is not obvious and the Electromagnetic compatibility (EMC) would be a nightmare…
So I searched on the Internet for a new battery, and I found this one : Tenergy Li-Ion 18650 11.1V 7800mAh. I could have assembled the battery by myself by buying each element separately which is much more cheaper, but I have enough work to do… 😉
There are many benefits :
- Battery’s weight better balanced,
- Space better distributed,
- One charger and one power monitor,
- More capacity than with the 2 others,
- The battery case is reinforcing the rigidity of the body.
It looks like this once integrated :
New battery integrated
I logically changed the charger and chosen a LTC4006 which fit perfectly to my application. Indeed, the LTC4008 doesn’t have a integrated termination charge like the 4006 and the use case of the robot (charging point of view) will be the same as a laptop, so I needed a charger compatible for this utilization.On the datasheet you can find a good application schema, which I have to modify to fit my expectations in order to handle the average 5-6A consumed by the robot…
However, I’m still keeping my
precious switching regulators :
- 1 PTN78060WAH : 5V power supply of the RasPi, the STM32 and the speaker’s amplifier.
- 1 PTN78060WAH : 3V night vision LED (+ mini fan).
- 3 PTN78020WAH : 7.4V legs power supply : 1 for each pair of leg (front +head, middle, rear).
I replaced the PTN04050C by the PTN78060WAH (boost converter), as I won’t use the 3.7V Li-Po battery anymore.
Here is the new electrical architecture :
Electrical Architecture Rev2
Hi there !
I finished the coxa articulation, this was a bit more complicated than expected, mostly for the shape design… I created a hole inside the part to be able to pass the cable inside, like this it will not be visible 😉 I didn’t had the time for running some stress tests on this part, so I will do it this week and update this post ^^
I still have to finish the leg. As you can see on the global view of Animabot, the legs are not fitting right on the femur : it is normal, and I will correct that this weekend !
Global view, body closed
Looks pretty good, no ?
On the last few days I have been finishing the fixation of the servos in the body. I changed the fixing studs for stronger ones. I still have a lot of work to do inside, but first I want to finish the legs.
I have advanced in the femur part, I still don’t know if I will keep this design because the upper part is flat and I’m not sure it combines with the body shape… But however, the servos are fixed inside, the part is relatively compact, and the cables should fit… so it’s not so bad 😉
Femur case outside
Femur case inside
Femur lateral cut
I also have temporally integrated this to the body, to see how it looks like and this gives also an idea of the size : Cool isn’t it ?
I think I will have to make the corners of the femur and the body a little bit rounder for the articulations movements… But I will see that with the articulations
The next step is to create the fixations between the body and the femur with a cable passage inside (tricky part…)
Hi guys, I have been working on the body for 1 week now, the results are encouraging 🙂 I have a definitive shape and volume for the body, and everything should fit inside (normally…)
I also found an effective solution for fixing the servos inside the body, I still have to make some strength analysis in Solidworks to check if everything is Ok.
The body is of course not finished, I have to create all the fixations for the electronic boards, the batteries, the head support, etc…
I have also to be careful with the screws I will use for fixing every parts, because I don’t want to have to cut them because they are too long… I have also to pay attention with the cables : ensure there is enough space for them 😉
The next steps are :
- Design the femur part
- Design the part between the femur and the coxa (articulation on the body)
This is my progression so far :