Colorectal cancer is a serious threat to human health. Colonoscopy is the most effective procedure for the inspection of colorectal cancer. However, traditional colonoscopy may cause pain, which can lead to the patient’s fear of colonoscopy. The use of active-motion colonoscopy robots is expected to replace traditional colonoscopy procedures for colorectal cancer screening, without causing pain to patients. This paper proposes an inchworm-like soft colonoscopy robot based on a rubber spring. The motion mechanism of the robot consists of two anchoring units and an elongation unit. The elongation unit of the robot is driven by 3 cables during contraction and by its inherent elasticity during extension. The balloon is selected as the anchoring mechanism of the robot. It has soft contact with the colon and will not damage the colon wall, which means no discomfort is caused. The elastic force test of the rubber spring shows that the elongation unit of the robot has sufficient restorative force to drive the robot to move forward and backward. The influence of the balloon’s expansion size on the dexterity of the robot head is analyzed, and the functions of the balloons are expounded. The balloon can not only assist the robot in its locomotion but also assist the robot to perform a better inspection. The robot can move successfully in a horizontal, straight, and inclined isolated pig colon, showing great clinical application potential.

Based on near-field acoustic levitation, a noncontact bearing with a spherical rotor was proposed to explore its potential application for novel supporting bearing of suspended gyro. The stator of the noncontact bearing has a hollow bowl-shaped configuration, in order to produce acoustic levitation force for a spherical object. Two orthogonal flexural standing waves were piezoelectrically generated and led to a traveling wave in the stator, and then the induced high-intensity sound in the air gap between the stator and spherical rotor could apply levitation force and even driving force for the spherical rotor. In this article, finite element model of a bowl-shaped piezoelectric stator was built, and the dynamic analysis and parametric optimization for the stator have been conducted. The prototypes were manufactured and vibration parameters of the stators were experimentally obtained. The test system for the noncontact spherical bearing was built, and its levitation and driving characteristics were measured. The spherical rotor successfully achieved levitation and noncontact rotation based on near-field acoustic levitation and the experimental results preliminarily indicate the feasibility of near-field acoustic levitation for suspended gyro.

Airflow sensor is a crucial component for monitoring environmental airflow conditions in many engineering fields, especially in the field of aerospace engineering. However, conventional airflow sensors have been suffering from issues such as complexity and bulk in structures, high cost in fabrication and maintenance, and low stability and durability. In this work, we developed a facile direct-writing method for fabricating a low-cost piezoresistive element aiming at high-performance airflow sensing, in which a commercial pen was utilized to drop solutions of single-walled carbon nanotubes onto tissue paper to form a piezoresistive sensing element. The encapsulated piezoresistive element was tested for electromechanical properties under two loading modes: one loading mode is the so-called pressure mode in which the piezoresistive element is pressed by a normal pressure, and another mode is the so-called bending mode in which the piezoresistive element is bended as a cantilever beam. Unlike many other developed airflow sensors among which the sensing elements are normally employed as cantilever beams for facing winds, we designed a fin structure to be incorporated with the piezoresistive element for airflow sensing; the main function of the fin is to face winds instead of the piezoresistive element, and subsequently transfer and enlarge the airflow pressure to the piezoresistive element for the normal pressure loading mode. With this design, the piezoresistive element can also be protected by avoiding experiencing large strains and direct contact with external airflows so that the stability and durability of the sensor can be maintained. Moreover, we experimentally found that the performance parameters of the airflow sensor could be effectively tuned by varying the size of the fin structure. When the fin sizes of the airflow sensors were 20 mm, 30 mm, and 40 mm, the detection limits and sensitivities of the fabricated airflow sensors were measured as 8.2 m/s, 6.2 m/s, 3.2 m/s, 0.0121 (m/s)⁻², 0.01657 (m/s)⁻², and 0.02264 (m/s)⁻², respectively. Therefore, the design of the fin structure could pave an easy way for adjusting the sensor performance without changing the sensor itself toward different application scenarios.

In this work, the performance evolution of a traveling wave type rotary ultrasonic motor (TRUM) in a high-rotating environment is studied. The dynamic model of the stator of the TRUM in the centrifugal field is established, and the centrifugal stiffening effect on the stator caused by the centrifugal force is described. Furthermore, the warping deflection of the stator caused by the centrifugal force is analyzed. It is found to change the original contact state and decrease the performance of the TRUM. The contact model between the stator and rotor in the centrifugal field is established. Moreover, the performance model of the TRUM in the centrifugal field is established, and the mechanism and varying trend of the mechanical performance of the TRUM in this condition are analyzed. Finally, the performance test system of the TRUM is set, and the mechanical performance of the TRUM at high angular velocities environment is measured. And the methods to improve the tolerance of the TRUM in the centrifugal field are put forward.