In recent days, orthopedic surgical robots play an increasingly important role in surgeries. Impedance/admittance control is a commonly used method for orthopedic surgical robots. In this paper, we proposed a variable admittance control method for orthopedic surgery. Instead of modifying virtual damping or mass which present in previous variable admittance control works, we present a new method by setting a dynamic reference point for virtual spring to improve operators’ boundary control ability during robot assisted orthopedic surgery. The reference point is the mean point of robot end effector trajectory in the past T period. The performance of the proposed controller was tested by conducting a cooperative experience, where all subjects were asked to finish a reaching task by using a Mini-robot.

In this paper, the exact analytical solutions are developed for the thermodynamic behavior of an Euler-Bernoulli beam resting on an elastic foundation and exposed to a time decaying laser pulse that scans over the beam with a uniform velocity. The governing equations, namely the heat conduction equation and the vibration equation are solved using the Green’s function approach. The temporal and special distributions of temperature, deflection, strain, and the energy absorbed by the elastic foundation are calculated. The effects of the laser motion speed, the modulus of elastic foundation reaction, and the laser pulse duration time are studied in detail.

The thermoelastic dynamic response of a clamped Bernoulli beam was studied when it was irradiated by a movable, temporally non-Gaussian, laser pulse. Both the energy absorption depth and the time decaying effects were considered. The temperature distribution, deflection, vibration acceleration, and stress of the beam were derived analytically, and the variations of them with time and space were illustrated. It was shown that the vibration frequency is independent of the scanning speed of the laser pulse. It is important to notice that, although the deflection of the beam is small, high vibration acceleration can be induced in microbeams, which is important for failure and fracture of the beam. Moreover, compressive stress is induced in the beam, but the importance of temperature-induced stress and deformation-induced stress may be different according to the duration time and moving speed of the laser pulse.

The design of geometric structures is a crucial approach for enhancing the performance of piezoelectric energy harvesters (PEH), which is thought to be an excellent method for capturing energy. This paper proposes a novel leaf-shaped energy harvester with excellent performance of electrical outputs, which consists of a unimorph curved beam, a straight beam and a tip mass. The shape of the curved beam is one leaf of a derivative of the lemniscate curve, with the shape being determined by an order parameter n, drawing bioinspiration from the spine. The numerical simulations based on 2D models indicate that the order parameter n plays a significant role in the output performance. It has been demonstrated that, for n = 2 and with a tip mass of 7 g, the output voltage per unit acceleration can reach up to 223.3 V g⁻¹ at a low frequency of 27.0 Hz. As n increases, the peak output voltage initially rises and flattens at higher values of n, demonstrating the influences of beam curvature and shape on the output performances. The effects of varying arc height and chord length on electrical output were also explored, revealing that lower arc heights can lead to higher voltages. The influence of the straight beam length on the energy harvester’s output performance was also investigated, demonstrating its significant impact. Overall, the findings contribute to a deeper understanding of the design parameters affecting the efficacy of leaf-shaped energy harvesters.

This study proposes an optimized design for the leg transmission structure of a quadruped robot, aiming to enhance the load-bearing capacity of the knee joint. Firstly, the dynamic simulation of the single leg's load-lifting process in the quadruped robot is conducted, indicating higher torque demands on the knee joint during this process. Therefore, a leg transmission mechanism, combining a ball screw mechanism and a crank-slider mechanism, is designed to effectively amplify the torque of the knee joint motor. Subsequently, a virtual prototype of the quadruped robot, incorporating this design, is constructed using Adams software. The foot trajectory of the robot is pre-planned, and the joint trajectories are obtained through inverse kinematics, using them as the driving functions for the quadruped robot to perform actions such as load lifting, static standing, and diagonal walking gait. Finally, the knee joint torque and corresponding motor driving torque of the quadruped robot's legs are measured and compared. The results demonstrate that the driving torque of the knee joint motor is effectively amplified by the leg transmission mechanism, with the maximum amplification observed during the initial stage of load lifting, reaching a magnification factor of nearly 7.66 times. This verifies the effectiveness of the proposed leg transmission mechanism in enhancing the load-bearing capacity of the knee joint.