RC servos have for a long time been the component of choice for robotics animation. They are relatively cheap, offers good torque/current relationship, and are easy to control. Applying a digital pulse, positions the servo in a position relative to the pulse width. But on a robot with many moving joints, e.g. a 18 dof hexapod, relatively heavy processing is needed to generate the pulses for all servos, especially if variable speed, and fluid simultaneous movement of the limbs are desired.

The solution to this problem is digital servos.

For my next CNC build I am going to make a PCB router, based upon a Proxxon KT70 compound table, and a dremel rotary tool.

I need to ensure that the steppers I select do have enough torque to turn the leadscrew, and therefore needed to find the minimum torque needed to turn the hand wheels. But the torque wrenches I could find in nearby tool stores where not suitable to measure such low torque values, so I needed to find the torque in a more practical way. Here is the description for my "Torque Approximator" setup.

My new stepper motor driver PCBs have finally arrived. I will soon have them assembled and ready for test. My main concern is whether or not I will be able to run them without a heatsink attached.

The boards are all SMD components, and to help anyone that would like to make their own boards, I will write and post a small tutorial on how to solder SMD components using standard soldering equipment. It is actually not that hard as long as you know the technique.

EDIT: Sept 21. The boards are now assembled, and are working perfectly. No heating when running the steppers, but still relatively hot when holding the steppers steady. I will try to get hold of a surface thermometer so I can measure the heat built up on the htermal pad, to determine wether a heatsing s required or not.

When I started using the AVR micro controllers back in 1999, I coded most of my applications in assembly. After a while GCC for AVR became available, and now, with the integration of GCC support in Atmels AVR studio, starting with GCC for the AVRs is now as easy as coding in assembly.

Atmel recently introduced the XMEGA AVR devices. These devices give a nice addition to the AVR family, introducing several new features ideally suited for robotics. Is this the perfect microcontroller to be used as a robotics brain?