Exoskeleton Test Bed | Upper-body Mannequin | Pneumatic Controller | Downloads
The Pneumatic Controller Board has 3 independently controlled air channels. The board hosts 3 linear valves, 3 valve drivers and 2 pressure sensors (with 2 channels each). The controller board can be interfaced to a computer using a DAQ device (we used Quanser q8-usb). LabVIEW applications to use the board can be downloaded from the Downloads tab.
Figure 1: Pneumatic controller board
Board Mechanical Design
All components are mounted on a rectangular plexiglass base using bolts and nuts. The base can be fabricated using laser-cutting (drawing for base can be found under downloads). Assemble all the components following the figure 1 above. The 2 protoboards (green boards) are mounted to make wiring convenient and avoid using long wires. The list of components is also available under Downloads.
Click on the figure 2 below to zoom or download.
Figure 2: Wiring diagram for pneumatic controller board
Wiring Diagram Notes:
- The part numbers highlighted with yellow were all sourced from Enfield Technologies
- A-CBL-M8-03P-F-0200 is a cable with blue, black and brown wires
- A-CBL-M8-04P-F-0200 is a cable with brown, white, black and blue wires
- AI (Analog Input) and AO (Analog Output) refer to connectors on Quanser DAQ
- The bottom right corner of diagram consists of Quanser DAQ and PC (both not mounted on Controller Board)
- The LabVIEW application on PC computes voltages that need to be sent to D1 controllers. These voltages are called ‘control effort’.
- PC talks to Quanser DAQ over USB.
- Quanser DAQ sends the ‘control effort’ voltages to D1 controllers using its connectors AO 0, AO 1, AO 2.
- The D1 controllers actuate the valves (LS-V05s) using the blue and brown wires. This changes the pressure in their respective air channels.
- The pressure sensors (SP5) send a voltage (proportional to the pressure in their air channels) to Quanser DAQ through connectors AI 0, AI1 and AI2.
- Quanser DAQ talks to PC over USB and PC uses sensor voltages as feedback in ‘control effort’ calculation.
Click on figures 3 and 4 to zoom or download. Figure 3 is a pneumatic circuit useful for making pipe connections. Figure 4 is a simpler variant of figure 3 and is provided for an audience who are either uninterested in air-flow directions or are unaware of pneumatic circuit symbols.
Figure 3: Pneumatic circuit
Figure 4: Pipe connections
Two LabVIEW applications are available for download. Application SingleChannel runs just one channel and application MultiChannel can control all 3 channels.
Your computer will require LabVIEW 32-bit 2016 (and up), LabVIEW Control Design and Simulation module, and support for your choice of DAQ. We installed Quanser RCP Toolkit to use our Quanser q8-usb DAQ device. The web links to all requisite software are also under Downloads tab. You would have to replace Quanser specific blocks in the LabVIEW code with blocks specific to your DAQ.
The applications use PID control to match pressure inside pneumatic actuators to desired reference pressure. The applications can generate many kinds of references – step signal, square wave, and sinusoidal wave.