Figure 7(a) presents an example of how to set up EtherCAT communication among the actuator, Simulink Real-Time target, and user console for a single actuator. A more detailed tutorial on how to organize an EtherCAT network is presented in [18]. The basic scheme-to create a Simulink block diagram that controls the actuator-is shown in Figure 7(b). It uses a controller block (blue) from the Compliant Joint Toolbox and the communication interface blocks (gray) provided by the Simulink Real-Time Toolbox. Summary and Future Directions This article presented the Compliant Joint Toolbox and introduced its main concepts. The basic use of the toolbox was demonstrated, and code examples and references to moredetailed information were given. We plan to extend the toolbox's capabilities to capture more nonlinear dynamics effects, such as nonlinear stiffness curves, and more advanced friction models, including hysteresis with memory, as well as more usage examples. Furthermore, we aim to interface the Compliant Joint Toolbox with (a) (b) Figure 6. (a) The WALK-MAN actuators and (b) the TREE actuators with which the authors interfaced the Compliant Joint Toolbox. Ethernet User Console Ethernet Actuator Simulink Real-Time Target Power Supply Wiring (a) Reference Controller PDO Transmit EtherCAT PDO Receive Hardware EtherCAT Measurements Block Interfacing (b) Figure 7. Examples for interfacing with actuator hardware on (a) the physical level and (b) the Simulink level. PDO: process data objects. 62 * IEEE ROBOTICS & AUTOMATION MAGAZINE * SEPTEMBER 2019