In this paper we present the development of a mesoscale self-contained quadruped mobile robot that employs two pieces
of piezoelectric actuators for the bounding gait locomotion, i.e., two rear legs have the same movement and two front
legs do too. The actuator named LIPCA (LIghtweight Piezoceramic Composite curved Actuator) is a piezocomposite
actuator that uses a PZT layer that is sandwiched between composite materials of carbon/epoxy and glass/epoxy layers to
amplify the displacement. A biomimetic concept is applied to the design of the robot in a simplified way, such that each
leg of the robot has only one degree of freedom. Considering that LIPCA requires a high input voltage and possesses
capacitive characteristics, a small power supply circuit using PICO chips is designed for the implementation of selfcontained
mobile robot. The prototype with the weight of 125 gram and the length of 120 mm can locomote with the
bounding gait. Experiments showed that the robot can locomote at about 50 mm/sec with the circuit on board and the
operation time is about 5 minutes, which can be considered as a meaningful progress toward the goal of building an
autonomous legged robot actuated by piezoelectric actuators.
In this paper we present the development of a small and fast LIPCA-actuated mobile robot. LIPCA (Lightweight
Piezoceramic Composite curved Actuator) is a piezo-composite actuator that uses a PZT layer sandwiched between
composite materials of carbon/epoxy and glass/epoxy layers to amplify the displacement. Three versions of LIPCA
robots have been developed thus far to implement a small and autonomous robot. The design of the first prototype was
inspired by a six-legged insect like a cockroach. Its maximum speed is 173 mm/sec with the voltage input of 400 Vpp at
40 Hz frequency. As the result of a slight modification in the design, a faster LIPCA robot was developed. However their
structures are not strong enough to carry a load heavier than 20 gram, which can be a major obstacle to implementing
autonomous robots. By several changes in the mechanism, the LIPCA-actuated robot has been improved such that it is
able to carry a weight as much as 60 gram. For all the prototypes we used two LIPCA strips that are placed oppositely in
the middle of the robot body. The LIPCA strips are driven by a square signal function of high AC voltage with the phase
difference of 180°. All the experimental results show a possibility of a small and fast walking robot actuated by LIPCA
without using any conventional electromagnetic actuator.
KEYWORDS: Actuators, Data modeling, Smart materials, Linear filtering, Signal processing, Control systems, Transformers, Autoregressive models, Analog electronics, Aerospace engineering
A smart material is known to be able to generate large force in broad bandwidth in a compact size. However it needs
relatively large voltage to drive it and this makes the system bulky. In this paper, first, we introduce an improved version
of miniaturized piezo actuator driver and modeling of the dynamics of the piezo actuator, LIPCA. ARX model was used
to model the dynamics of the LIPCA. We applied rectangular waves to the LIPCA and measured its responses with a
strain gauge and a signal processing circuit. A 5th order model was obtained from the input/output data and applying
identification algorithm. Secondly, we designed a simple PID controller based on the obtained model to improve the
characteristics of the LIPCA actuator.
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