Biorobots involve embedding artificial components into a living insect to transform it into a controllable robot, which comes with the advantages of low energy consumption, quietness, and flexibility. However, no models have yet been developed to describe the randomness-filled motions of biorobots, and their unique biological properties are also underutilized. In this work, the locomotion responses of a biorobot to electrical stimuli were summarized. The constant-current signal was found to have a higher capacity for sustained stimuli than existing methods. The joint influence of wall and current factors on cockroach behavior was explored to establish an environment-adaptive control model describing their locomotion. This model was then used to propose an navigation method enhanced by the inherent nature of a biorobot. In an indoor scenario, the proposed method achieved a success rate of 78.6% with minimal runtime and stimulus number while the control group using conventional navigation methods achieved a success rate of 30%, with two or three times the runtime and stimulus number. Compared with other approaches, the proposed method facilitates high-precision and long-range navigation with a short navigation time and very low control costs.

The design and control of hexapod robots have become an active research field due to the ability to achieve adaptive and stable multi-terrain locomotion. However, existing hexapod robots focus on the integration of flexible pitch joints to enhance their obstacle-crossing and slope-climbing abilities, and few biological observations have been made to gain insight into the agile steering mechanisms of hexapod insects. Herein, we observed the steering movements of Madagascar cockroaches. Observations showed that cockroaches exhibited specific phase relationships in addition to regular tripod gait pattern during steering. Moreover, we also found that a smaller steering radius resulted in a larger lateral bending angle of the thoracic segments. Inspired by this, a hexapod robot with a flexible torso (F-RHex) was designed and fabricated. Bio-inspired gait patterns were abstracted and simplified into two steering strategies: gait-based and mix-based. Compared to the purely gait-based strategy, the F-RHex testing results demonstrated a ~27.4% reduction in turning radius and ~40% enhancement in steering velocity, implying that the mix-based strategy offers superior steering capability.

A small-scale jumping robot can reach obstacles much larger than its size. It is important for a jumping robot to perform intermittent jumps to cross through rough terrains. However, the limitations of conventional structures hinder the further integration of functions to a miniature (sub-50 g) jumping robot. No sub-50 g jumpers could perform intermittent jumps with adjustable jumping trajectories. In this work, we proposed an origami-based miniature jumper, which performed intermittent jumps with adjustable omni-directional trajectories. The intermittent jumps were achieved by the jumping and self-righting mechanisms, which were actuated by a single motor. The clockwise and counterclockwise rotation of the motor actuated the loading, self-righting and triggering process, respectively. The jumping height was adjustable by adjusting the rotation angle of the motor. Meanwhile, the take-off pitch & yaw angle adjustment methods were integrated into the robot. Therefore, we demonstrated a 9 cm, 13.5 g prototype with functions of re-loading, self-righting, jumping height adjustment and take-off pitch & yaw angle adjustment. The robot could adjust jumping height from 16 to 34 cm and self-right for the next jump. The results revealed that our robot could jump across different obstacles with different scales and directions. The mobility was greatly increased compared with other miniature jumping robots.

Jumping motion is an effective way to overcome large obstacles, especially for the miniature robots. However, controlling of the jumping trajectory on a centimeter scale robot is not easy due to the limitation of size and payload. None of the jumping robots lighter than 90 g achieved the feedback control of their jumping height and take-off angle independently. In this work, we proposed a miniature 6 g jumping robot that ensured the feedback control of jumping trajectory. Two simple PD controllers were used in take-off angle and jumping height control, respectively. The robot can control its jumping height from 0 to 73cm, take-off angle from −20° to +20° with respect to the vertical direction. The control errors of the jumping height and the take-off angle were less than 5 cm and 2°, respectively. The robot can hop upon different obstacles exactly, greatly increased the controllability of the micro jumping robot.

Beetles can walk smoothly on the meshed surface without slipping or getting stuck in the meshed surface due to its stiffness-variable tarsi and expandable hooks on the tip of tarsi. In this study, we find that beetles bend and open their claws proactively to walk freely. Inspired by the mechanism, we designed a centimeter-scale climbing robot, equipping an artificial claw to open and bend in the same cyclic manner as the natural beetles. The robot can climb freely on the mesh surface of 30° without being stuck at a speed of 26.18 mm/s (0.3 body length per second), and the speed was 37.5 mm/s on the 55-degree rough slop. This is the first demonstration of a centimeter-scale robot that can climb on the mesh surface.

Jumping is beneficial for microrobots because they have to face obstacles larger than their height frequently. However, compacting a jumping mechanism into the small body of a microrobot is exceptionally challenging. Instead of assembling a bio-inspired microrobot, the insect itself can be transformed into a jumping robot. Herein, we demonstrated the first-ever biohybrid jumping robot that retained the natural jumping ability of a locust. The fast kicking of the locust's hindleg was mainly induced by two muscles, flexor muscle, and extensor muscle. The elaborate structure and accurate collaboration of the muscles are critical for leg kicking, contributing to the co-contraction process. In this article, we investigated the sequences of muscular activities and demonstrated the co-contraction control exogenously. The kicking control of the hindleg relies on the accurately overlapped stimulation and the independently modulated waveform. With the help of a tiny wireless stimulator, the cyborg locust was remotely controlled to jump an average of 10.4 cm high and 42.6 cm far. Moreover, the cyborg locust retained its internal body righting mechanism, which means the robot can quickly recover its posture for consecutive jumping. This work is a foundational step towards a fully controllable biohybrid jumping robot.

The development and control of biological actuators have been an active research field. Biological actuators revealed high mobility with compact dimensions, which is critical for the design of microrobots. The powerful kicking motion of the locust is important for its quick jumping. Herein, we examined the kicking process of the locust’s hindleg and controlled the flexion and extension motions via exogenous stimulation. Unlike a simple extension of the leg, co-contraction is adopted by locust to store energy and increase jumping power. Thus, we imitated the co-contraction process and transformed the locust’s hindleg into a biological jumping actuator. Through coordinating the kicking of bilateral hindlegs together, we achieved the jumping control of a locust.

Unlike biomimetic methods, the insect–computer hybrid is an alternative approach to developing insect-scale robots. Insect–computer hybrid is a technique that transforms a living insect into a controllable robot by embedding it with artificial devices. In this article, a beetle (Mecynorrhina torquata) was transformed into a hybrid flying system by mounting an electronic backpack and implanting electrodes on it. Wing trajectories during fictive flight climbing and flight diving were captured to investigate the natural flight-height control of beetles. Compare with the electrically induced wing trajectories via basalar, subalar, and third axillary (3Ax) muscle stimulations, we hypothesized that the basalar muscles are involved in ascending flight, whereas the 3Ax muscles function to reduce the flight-height. By reproducing the electrical stimulations on bilateral muscle pairs during free flights, we found that stimulations of the basalar muscle pair increased vertical accelerations. In contrast, the 3Ax muscle pair's stimulation decreased vertical accelerations gradually as a function of the electrical stimulation frequency. Accordingly, a proportional-derivative feedback controller was proposed to maintain the beetles' flight-height using frequency-dependent electrical pulses on the basalar and 3Ax muscles. In this article, the altitude control of a free-flying beetle was demonstrated for the first time.