Due to budget cost of pneumatic system, it becomes of comparable to find smart materials that has the properties the specification is looking for.
Tension springs on the left images has a similar mechanical properties to a pneumatic air muscle and meets the specification for the actuators.
An example of an un-powered exoskeleton is shown on right image. The tension spring will store the potential energy when the user squats down. With the aid of gravity, the squat down pulls the tension spring storing the energy. The spring shape recovery is stop with a ratchet and pawl. The ratchet and pawl enable the spring to be loaded with potential energy without releasing it. The pawl release is control using a high torque servo motor. The Servo motor is control using the EMG control LabView code either from a computer or on board myRIO. The tension spring also aid the user by supporting the user when squatting down.
Author's Notes
“The pneumatic air muscle will be simulated on the labview code but won't be implemented on the prototype due to cost issue. Mounting area for the pneumatic air muscle will be included on the exoskeleton, to show the possibility of usage of a pneumatic actuators.”
Comments