title: A biological micro actuator: graded and closed-loop control of insect leg motion by electrical stimulation of muscles.
abstract: In this study, a biological microactuator was demonstrated by closed-loop motion control of the front leg of an insect (Mecynorrhina torquata, beetle) via electrical stimulation of the leg muscles. The three antagonistic pairs of muscle groups in the front leg enabled the actuator to have three degrees of freedom: protraction/retraction, levation/depression, and extension/flexion. We observed that the threshold amplitude (voltage) required to elicit leg motions was approximately 1.0 V; thus, we fixed the stimulation amplitude at 1.5 V to ensure a muscle response. The leg motions were finely graded by alternation of the stimulation frequencies: higher stimulation frequencies elicited larger leg angular displacement. A closed-loop control system was then developed, where the stimulation frequency was the manipulated variable for leg-muscle stimulation (output from the final control element to the leg muscle) and the angular displacement of the leg motion was the system response. This closed-loop control system, with an optimized proportional gain and update time, regulated the leg to set at predetermined angular positions. The average electrical stimulation power consumption per muscle group was 148 µW. These findings related to and demonstrations of the leg motion control offer promise for the future development of a reliable, low-power, biological legged machine (i.e., an insect-machine hybrid legged robot).
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Feng
authors.initials: F
authors.lastname: Cao
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Tat Thang
authors.initials: TT
authors.lastname: Vo Doan
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Yao
authors.initials: Y
authors.lastname: Li
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Daniyal Haider
authors.initials: DH
authors.lastname: Sangi
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Jie Sheng
authors.initials: JS
authors.lastname: Koh
authors.affiliation: School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore.
authors.forename: Ngoc Anh
authors.initials: NA
authors.lastname: Huynh
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Mohamed Fareez
authors.initials: MF
authors.lastname: Bin Aziz
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Hao Yu
authors.initials: HY
authors.lastname: Choo
authors.affiliation: Division of Neurosciences, City of Hope Medical Center, Duarte, California, United States of America.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ikeda
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Berkeley, California, United States of America.
authors.forename: Pieter
authors.initials: P
authors.lastname: Abbeel
authors.affiliation: Department of Electrical Engineering and Computer Science, University of California, Berkeley, California, United States of America.
authors.forename: Michel M
authors.initials: MM
authors.lastname: Maharbiz
authors.affiliation: School of Mechanical and Aerospace Engineering, Nanyang Technological University, Singapore.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Sato
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D001517:Coleoptera; D019054:Evoked Potentials, Motor; D005121:Extremities / Q000294:innervation / Q000502:physiology*; D009068:Movement; D018482:Muscle, Skeletal / Q000293:injuries / Q000502:physiology*