This Affordable DSM Radio Transmitter Is Perfect for Long-Range Robot Control

The most amazing robot in the world is useless if it can't be reliably controlled. But remote control is not a trivial problem, as every communication method has some disadvantages. Cellular costs money and requires reception. Wi-Fi has a limited range. Many radio frequencies are regulated by governments or have high interference. So it can be difficult to decide on a communication technology, and that is before you even start designing the controller. Luckily, James Bruton did all of that work for us and designed this affordable DSM radio transmitter that is perfect for long-range robot control.

You may recall that Bruton designed a universal robot remote controller a couple of years ago, but that was fairly expensive, had a limited range, and only worked with ROS (Robot Operating System). This new design solves all of those problems. It has a much a longer range and works with hobby RC receivers, so it is suitable for a wide range of robot brains. It also uses inexpensive components and doesn't cost much to build —at least not when you consider the capability. The standard setup has four three-axis joysticks, four toggle switches, and four momentary push buttons, which should be enough for some very complex robots.

dThe key to this remote's long range is DSM (digital spectrum modulation) radio transmission, which is a relatively new communication technology in the RC world. It uses DSSS (Direct-Sequence Spread Spectrum) modulation that uses wide signal bandwidth, but narrow data bandwidth, to make the transmission more resilient against interface and perform better at long ranges. In this case, Bruton used a pair of very affordable (currently $4.99) OrangeRX DSMX/DSM2 2.4GHz radio transmitter modules. This project only covers the remote control, but those transmitters will work with lots of different hobby radio receivers.

Each of those OrangeRX modules can transmit 10 different radio channels. By using both, the remote control has 20 total channels to work with — exactly enough for the aforementioned controls. An Arduino Mega 2560 development board collects the values from the joysticks, switches, and buttons, then sends the data to the OrangeRX modules via serial. Power comes from four 18650 lithium battery cells and the enclosure is 3D-printable.

As usual, Bruton published all of his files and code on GitHub so you can build this remote control yourself. Assuming you have access to a 3D printer, it should cost around $100 to build. That puts it on par with entry-level hobby DSM transmitters, but this DIY design has far more capability.