Conventional ultrasonic drills can drill into rocks using high frequency axial vibration, which feature lower power and lower preload force, thus they could become a very attractive solution for future deep-space exploration. However, drill cuttings cannot be removed effectively with the increase of drilling depth by conventional ultrasonic drills that only driven by longitudinal vibration. To address this issue, a Rotary-Percussive Ultrasonic Drill (RPUD) is proposed, which employs one single PZT transducer to generate rotary-percussive motion for rock fracturing. RPUD is composed of a PZT transducer, a percussive unit, a rotary unit, and a drill tool. The percussive unit enlarges the longitudinal vibration of front part of PZT transducer, and provides a reciprocating percussion to the drill tool. The rotary unit transforms longitudinal vibration of rear part of PZT transducer into longitudinal-torsional vibration to drive the drill tool to rotate continuously. The rotary and percussive motions are independent of each other, and can be adjusted separately. To make the rotary and percussive motions move synchronously, finite element method is employed to tune the resonance frequencies of the rotary unit and percussive unit to be close by transient analysis. Experimental results show that RPUD can improve removal efficiency of the drill cuttings due to its rotary motion, compared with conventional ultrasonic drills.

An underactuated robotic finger is proposed and studied for capturing non-cooperative objects, featuring an underactuated rigid-mechanism that can brake residual motion of non-cooperative targets. The finger consists of three joints driven by two actuators, and a set of one-input-two-output planetary gears is introduced to realize force transmission by using the ring gear and the planetary carrier to drive the two joints. The rotation of the ring gear and the planetary carrier are governed jointly by the inputs and the external force. In the process of capturing a moving target, the proposed robotic finger can effectively limit the impact force peak due to collision with the target. Moreover, the recovery time of the joint can be adjusted by changing the input torque of the motor, which can be set to achieve optimal recovery process for different tasks. A prototype has been built to study the proposed design of the robotic finger, and experimental results have confirmed its desirable characteristics.

Drilling & coring is considered as an effective way to acquire deep sample on the moon. Since the lunar regolith environment in depth is unknown, sampling drill should be developed to adapt to the undetermined drilling medium on the moon. Once mechanical system of sampling robot was finished, control strategy is a key to realize the high-efficiency drilling process. Since composition of lunar regolith is complicated, it's not easy to evaluate all the physical parameters to judge the drilling difficulty level. This paper proposes a novel idea of lunar regolith drillability which is established on the rate of penetration under the given standard terms. Drillability is selected to describe the drilling difficulty level which can be identified online by use of pattern recognition method of SVM. Control algorithm tunes the drilling parameters to adapt to the recognized medium. Experiments are conducted to verify the drillability online recognition based intelligent control strategy can make sampling robot adapt to complicated drilling media.

This paper deals with a tracked robot that consists of the proposed crawler module, in which a planetary gear reducer is used as the power transmission device to give two different outputs with just one actuator. This under-actuated system could perform posture control through the interaction between the front and rear modules. On occasion, the posture that the front module is lifted up can make the robot overcome obstacles actively and easily. To find out the controllable postures, the static analysis of the robot has been conducted. In this paper, we provide the control strategy for performing the posture control, and propose the control methods including direct, indirect, and cooperative control to conduct the posture control. Experimental tests show the effectiveness of the control methods.

This paper presents a tracked robot composed of the proposed crawler mechanism, in which a planetary gear reducer is employed as the transmission device and provides two outputs in different forms with only one actuator. When the crawler moves in a rough environment, collision between mechanism and environment inevitably occurs. This under-actuated crawler can absorb the impact energy that should be transmitted to the actuator. A modular concept for the crawler is proposed for enlarging its use in robot systems and mechanical design of a modular crawler is conducted. Using this crawler module, a four-crawler-driven robot is realized by easily assembling. Experiments are conducted to verify the proposed concept and mechanical design. A single crawler module can well perform the proposed three locomotion modes. The four-crawler-driven robot has good adaptability to the environment which can get over obstacles both passively and actively.