# Looking for Raspberry Pi HAT/Servo/Sensor recommendations **URL:** \ **Category:** Uncategorized\ **Created:** [24 January 2023 08:28 UTC](https://forum.core-electronics.com.au/t/looking-for-raspberry-pi-hat-servo-sensor-recommendations/16205 "2023-01-24T08:28:01Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![Troy189808](https://avatars.discourse-cdn.com/v4/letter/t/50afbb/32.png) [@Troy189808](https://forum.core-electronics.com.au/u/Troy189808)\ **Post date:** [24 January 2023 08:28 UTC](https://forum.core-electronics.com.au/t/looking-for-raspberry-pi-hat-servo-sensor-recommendations/16205/1 "2023-01-24T08:28:01Z")
As the saying goes “Long time listener, first time caller”… I’m working on a project to separate, identify and sort Lego parts from a source container of mixed parts. I’m leveraging previous projects that have been posted online (such as Daniel West’s Universal Lego Sorter [link](https://www.raspberrypi.com/news/raspberry-pi-lego-sorter/))in terms of the mechanics, and have separated the design into stages that will each need motors &/or sensors. The current plan is to have a Raspberry Pi CM4/Carrier board combo run as the core of the project. Stage 1: Source bin and feeder to stage 2 My current thinking is to use a linear actuator to push one side of an angled container whilst a vibrating motor shakes the contents to reduce friction (based on a volume of particles displaying liquid like properties when vibrations are passed through, e.g. sand). Output with be pushing a small quantity of parts into stage 2 for physical separation. A sensor in stage 2 will act as one of a series of on/ff switches for stage 1 Stage 2: Separator. A v-shaped channel, with fixed support at the exit end, suspended via springs at the opposite end, using vibration to shake pieces down and onto a conveyor (Stage 3). I think the way to go is to use a break beam sensor to detect the drop of this section and send an off signal to the motors in the previous. Another break beam sensor at the exit end, signalling a stop for the vibrating motors in the stage 2, and activating stage 3. Stage 3: Identification I’m thinking a conveyor through a camera box, exiting to a funnel with a variable position exit chute. Another 2 break beam sensors (one to detect a part in the camera box, another to detect it’s exit into the output chute, and a Raspberry Pi camera to capture an image for identification (this will be sent over network using a queuing broker to a machine learning server). Once the ID-query-response returns a result (either matching sort parameters or default null), restarts the conveyor to eject the part. Stage 4: Sort Output Here I’m thinking a stepper motor to control an output chute by rotating through 180 degrees into a series of output bins. A final break beam sensor in the output chute to signal Stage 2 to output another part into the system. From the Raspberry Pi out, here’s what I think I need: 1. Motor Control Hat (or multiple, stackable) capable of controlling all the motors, ideally with software libraries for Python/Linux 2. Motors: Linear actuator Vibrating motor x 2 (perhaps 4? if paired would be more effective) Conveyor motor (standard servo or DC motor) Stepper motor 3. Sensors: Break beam sensors x 4, or alternative. Support software libraries in the same language as the motors would be ideal to keep things as simple as possible R-Pi CSi connected camera/lens Based off Daniel’s project, I plan on using a Tensor Flow convolutional neural network, with MQTT brokering between the AI engine and the Raspberry Pi. Any thoughts or advice on this, especially around the Pi controlled hardware, is appreciated. ---
**Author:** ![Trent5487676](https://yyz2.discourse-cdn.com/flex028/user_avatar/forum.core-electronics.com.au/trent5487676/32/4583_2.png) [@Trent5487676](https://forum.core-electronics.com.au/u/Trent5487676)\ **Post date:** [25 January 2023 03:46 UTC](https://forum.core-electronics.com.au/t/looking-for-raspberry-pi-hat-servo-sensor-recommendations/16205/2 "2023-01-25T03:46:00Z")
Hi Troy, Welcome to the forum 🙂 I hadn’t seen the video of Daniel West’s build, it’s very impressive and looks to be a solid design to base your project on. Overall your game plan sounds sensible to me, I can’t see any major issues that might come up, every build will have little surprises though. For any complex project I work on I like to have a little sanity check for each stage testing “Is there a simpler way to do this?” with either less parts or less complexity. The only point I can think of currently is it might be worth considering servo motors for the stage 4 sort output rather than stepper motors. Either should be able to achieve the aim of 180 degree positioning, but steppers will require a dedicated stepper driver whereas you might find a servo you can control directly from the Pi, then only need a DC power supply rail to support it. The big picture plan looks good. I say go for it with stage 1 and once that is functioning well enough begin the next stage. Lessons learned in stage 1 might allow you to change course before you have committed the budget to something for all 4 stages if hiccups arise.