Abstract
McKibben muscles have been shown to have improved stiffness characteristics when operating hydraulically. However when operating pneumatically, they are compliant and so have potential for safer physical human–robot interaction. This paper presents a method for rapidly switching between pneumatic and hydraulic modes of operation without the need to remove all hydraulic fluid from the actuator. A compliant and potentially safe pneumatic mode is demonstrated and compared with a much stiffer hydraulic mode. The paper also explores a combined pneumatic/hydraulic mode of operation which allows both the position of the joint and the speed at which it reacts to a disturbance force to be controlled.
Highlights
As robots become more widespread, there are changes in the environments in which they work from purely industrial manufacturing plants to arenas where they are likely to experience close physical interaction with humans
In the work presented in this paper, an alternative avenue is explored: the inherent safety of McKibben muscles is combined with a method allowing increased stiffness through the introduction of an incompressible fluid into the actuator
The Pulse-width modulation (PWM) duty cycle of the signal applied to the two valves is given by the following pseudocode, where Hydraulic_PWM and Pneumatic_PWM are the duty cycles for each valve type: Pneumatic mode Hydraulic_PWM = 100% Pneumatic_PWM = proportional–integral–derivative controller (PID)(Target Position – Position Encoder) Hydraulic mode Hydraulic_PWM = PID(Target Position – Position Encoder) If(Target Position < Position Encoder) Pneumatic_PWM = 100% //Pressurises reservoir to maximum else Pneumatic_PWM = 0% //Reduces reservoir pressure to zero
Summary
As robots become more widespread, there are changes in the environments in which they work from purely industrial manufacturing plants to arenas where they are likely to experience close physical interaction with humans. In the work presented in this paper, an alternative avenue is explored: the inherent safety of McKibben muscles is combined with a method allowing increased stiffness through the introduction of an incompressible fluid into the actuator. In this way, both a structurally compliant and potentially safe mode of operation and a rigid but more accurate mode of operation are possible.
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
