Date of Award


Publication Type


Degree Name



Mechanical, Automotive, and Materials Engineering


Granular jamming, Soft actuator, Soft robotics







Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.


The field of soft robotics has been increasing popularity and importance in last decade with its groundbreaking applications in the field of delicate food handling industry and rehabilitation of limbs and fingers of stroke affected patients. The area of soft robotics seeks to improve robot safety, allowing them to function in circumstances where standard robots cannot.

This research is focused on pneumatically actuated soft robots as they are efficient, easily controlled, affordable, and well researched. These robots consist of one or more soft actuators, made of silicone elastomers with low material hardness. Low hardness silicone actuators are structurally weak and cannot generate functional forces, which can be rectified by simply increasing the hardness of the material, resulting in compromising softness of the robot. This research attempts to provide a solution to increase structural stability and force output of soft actuator without compromising softness of the material. These were achieved in two ways; one, by improving the cross-sectional profile of the actuator, with an addition of vacuum functionality which increases degree of freedom by one. Two, by attaching a granular jamming component to the actuator, which can change its stiffness actively based on the vacuum applied to it.

In this research, the soft actuator was made of Eco-Flex 00-30 silicone and ground coffee was used as granular material for jamming. The actuator was designed on CATIA, and simulation analysis was carried out in ANSYS. A simulation study is conducted to optimize the design parameters to improve bending angle. The jamming components are attached on either side of the actuator and filled with ground coffee which provides controlled stiffness. The actuator was fabricated by molding, all molds are 3D printed with polylactic acid. The actuator was powered by an electric air pump. The actuator is evaluated for bending angle and blocking force at the tip. 280% more bending was achieved under vacuum when compared to conventional design. The blocking force was increased by 270% upon implementing jamming component. The force output obtained per unit pressure applied when compared to present literature increased by 4 times. Lastly, these methods can be implemented to improve the performance of any soft pneumatic actuators.