Radio Controls and Accessories

Specifications and Controls

mechanism. And the charging mechanism will not activate until you disengage the motors, either manually or programmatically.

All ActivMedia robots are servers in a client-server architecture. You supply the client computer to run your intelligent mobile-robot applications. The client can be either an onboard piggy-back laptop or embedded PC, or an offboard PC connected through radio modems or wireless serial Ethernet. In all cases, that client PC must connect to the HOST serial port of the robot’s microcontroller in order for the robot and your software to work.

For the piggyback laptop or embedded PC, that serial connection is a cable. Radio modems simply replace that serial cable with a wireless tether. Accordingly, if you have radio modems, one is inside your robot and connected to the controller’s HOST serial port, and the other modem plugs into a serial port on some offboard computer where you run your client software. Hence, in these configurations, there is one dedicated client computer. (See Appendix C for radio modem settings.)

Figure 13. Client-server connection options.

Radio Ethernet is a little more complicated because it lets you use many different computers on the network to become the robot’s client. A special onboard Serial- Ethernet accessory that we provide is a standard wireless Ethernet radio which connects to your local TCP/IP network through an Access Point. But it’s different from most standard wireless Ethernet devices in that it also connects to the HOST serial port on the robot’s microcontroller. It works by automatically translating network-based Ethernet packet communications into streaming serial for the robot controller and back again. Accordingly, you may run the robot’s client on any network PC just as if that client PC were connected directly to the robot’s controller. (See Appendix D for Serial Ethernet settings.)

A major disadvantage of the wireless Ethernet-to-serial device, however, as well as for radio modems, is that they require a constant wireless connection with the robot. Disruption of the radio signal—a common occurrence in even the most modern installations—leads to poor robot performance and very short ranges of operation.

This is why we recommend onboard client PCs for wider, much more robust areas of autonomous operation, particularly when equipped with their own wireless Ethernet. In this configuration, you run the client software and its interactions with the robot controller locally and simply rely on the wireless connection to export and operate the client controls, such as through X-Windows or VNCserver. Moreover, the onboard PC is often needed for local processing, such as to support a laser range finder or to capture and process live video for vision work.