Daisy Driver 2.2
Today I’m delighted to bring you an update to my earlier post about the Daisy Driver motor controller. The latest version meets all my requirements and now I can focus on the next parts of the Sixi 3 robot arm project. I’m making it availble to you right here, right now. Join me in building a world with more interesting robots and read on for all the details.
What’s in the board?
The Daisy Driver can do so much!
- The STM32F405 brain is huge and crazy fast. 168 MHz CPU/210 DMIPS, up to 1 Mbyte of Flash.
- The TMC2130 motor driver can handle up to 1.5amps and includes current change sensing, which could be used for collaborative robots that sense collisions.
- The IPS2200 rotation sensor is absolute – no need to “home” – touch off a limit switch – when the robot turns on. It always knows where it is.
- The rotation sensor is also hollow-shaft. A wire can go through the sensor, through the center of the gearbox, and out to the next Sixi 3 actuator.
- The board can be connected to its neighbors in a linked-list of actuators. They talk to each other through the CANbus network using the CANOpen protocol. This makes electrical work a breeze.
- Since every CAN device needs a unique address, 6 dip switches make it easy to setup. No pads to solder!
- It also has a USB connection so you can use a normal Serial interface from your favorite app to talk to the device.
- The JTAG programming pins make it simple to upload new code from Arduino. Check out our daisy driver Arduino firmware.
- The RGB LED is a handy status indicator. Have it display CANbus traffic, sensor angle, or morse code!
So why is this important?
The Sixi 2 robot was my fourth robot arm. It was big, strong, and gorgeous. But it was also 1300 parts in 250 types and it had long cables that ran from the wrist, through the elbow, and into the base. If I’m going to make robots easy for everyone then this is not workable. So I went back to the drawing board again and decided to build a modular robot arm out of identical pieces. The Sixi 3 actuator has less than 50 parts in about 20 types. Even with six actuators in a chain to make a Sixi 3 robot arm that’s less than 300 parts total and none of them are one-offs. production and maintenance at scale! The factory must grow.
Why Daisy Chain?
There are three main ways to wire the joints in a robot arm: all-outside, all-inside, and daisy chain.
All outside wires are easy for maintenance but hard to manage while the robot is running. I’ve had robots try to strangle themselves on their own cabling by accident.
All inside wires are tidy and elegant, but doing any service work means dismantling the entire arm.
Daisy chain is the best of both worlds: no outside wiring and easy maintenance. I’ve tested replacing the elbow of a Sixi 3. It takes about 10 minutes.
So now what?
Next up is to share the goodness with you. The board is available now. More are on the way and I can now refocus my energy on the next step in the bigger picture: using one arm to assemble another arm. As that happens I’m going to need more actuators, more boards, and more gearboxes, plus the Robot Overlord software to run everything.
I’m very interested in talking to anyone that would like to help make an awesome harmonic gearbox, anyone into creating data sheets for electronics, anyone who sees the potential.