In recent years, the field of robotics has witnessed significant advancements, particularly in the development of soft robots that offer enhanced adaptability and safety in unstructured environments. Traditional rigid robots, while effective in controlled settings, often struggle with complex tasks due to their limited degrees of freedom. In contrast, soft robots, constructed from elastic materials, can undergo substantial deformations such as bending, twisting, and stretching, enabling them to navigate confined spaces and interact safely with humans. This has broad applications in areas like disaster response, scientific exploration, medical rehabilitation, and industrial automation. However, many existing soft robots are designed for单一运动模式, limiting their versatility in dynamic scenarios. To address this, we propose a modular soft robot system leveraging dual-material 3D printing technology, which enhances performance, reliability, and functionality. Our work focuses on designing, modeling, manufacturing, and testing modular actuators that can be combined for multi-mode operations, contributing to the growing field of China robot innovations.
The core of our approach lies in optimizing actuator structures through dual-material printing, where strain-limiting layers and expansion layers are integrated to improve output torque, tip force, and longevity. By employing materials like DC737 and Ecoflex 00-20, we achieve precise control over deformation behaviors, reducing issues like material fatigue and cracking common in traditional designs. This paper details the design of torsional and spiral actuators inspired by origami and biological mechanisms, respectively. We conduct extensive simulations using Abaqus for fluid-structure interaction analysis, develop mathematical models based on principles like virtual work and projection methods, and utilize a custom-built dual-material 3D printer for fabrication. Experimental results validate our designs, showing significant improvements in performance metrics such as torsion angles and blocking forces. Furthermore, we demonstrate the robot’s adaptability through modular combinations, enabling tasks like sorting and grasping in varied environments. This research not only advances the capabilities of soft robots but also underscores the potential of China robot technologies in addressing real-world challenges.
Our modular soft robot system begins with the design of individual actuators, each tailored for specific motions. The torsional actuator, inspired by square-twist origami patterns, incorporates alternating materials to simulate mountain and valley folds. Specifically, harder DC737 sections act as strain limiters, while softer Ecoflex 00-20 portions facilitate expansion under negative pressure. This design enables clockwise or counterclockwise torsion, mimicking human wrist movements. Key parameters include overall height, base and top widths, wall thickness, and crease dimensions, which are optimized through iterative simulations. For instance, the torsional actuator achieves a maximum rotation of approximately 78 degrees under -75 kPa, with a torque output of 320 N·mm. The spiral actuator, drawing from DNA helices and plant tendrils, features angled chambers that induce coupled bending and twisting motions. By varying the chamber angle from 0° to 60°, we control the degree of spiral deformation, with larger angles resulting in higher torsion and reduced bending. This actuator can complete over 360 degrees of rotation at 100 kPa, making it ideal for grasping slender or heavy objects. The integration of these modules into a cohesive system allows for reconfigurable robots capable of linear motion, torsion, and complex manipulations, highlighting the flexibility of China robot designs.
To ensure the reliability of our designs, we performed finite element analysis (FEA) using Abaqus, modeling the hyperelastic behavior of the materials with the Ogden strain energy density function. For DC737 and Ecoflex 00-20, the Ogden parameters (N=3) were derived from experimental data, enabling accurate prediction of large deformations under pressure loads. The torsional actuator simulation revealed that negative pressure causes the softer layers to collapse first, leading to torsion, with results closely matching experimental measurements. Similarly, the spiral actuator simulations demonstrated how chamber angles influence bending and torsion, with projections on orthogonal planes used to decouple the motions. The mathematical models further refined our understanding; for the torsional actuator, we applied virtual work principles to relate internal pressure to torsion angle and torque, while for the spiral actuator, we used iterative methods and projection analysis to compute displacements and forces. These models confirmed that dual-material structures enhance mechanical efficiency, with the spiral actuator producing higher blocking forces compared to single-material counterparts. The equations derived from these analyses are summarized below, providing a foundation for optimizing China robot performance in various applications.
For the torsional actuator, the torsion angle $\theta_{tor}$ is given by:
$$ \theta_{tor} = 2 \arcsin\left( \frac{b \cos \delta}{\sqrt{2} a} \right) $$
where $a$ is the base edge length, $b$ is the slant height, and $\delta$ is the angle between the slant and horizontal planes. The torque $\tau$ can be expressed as:
$$ \tau(\theta_{tor}) = p \frac{dV_c}{d\theta_{tor}} + \frac{dW_s}{d\theta_{tor}} $$
Here, $p$ is the pressure, $V_c$ is the internal volume, and $W_s$ is the stored elastic energy. For the spiral actuator, the bending angle $\alpha$ and torsion angle $\beta$ are computed iteratively. The incremental bending angle $\Delta \alpha^{i+1}$ is:
$$ \Delta \alpha^{i+1} = \arccos\left( \frac{\mathbf{r}_{AB}^i}{|\mathbf{r}_{AB}^i|} \cdot \frac{\mathbf{r}_{AB}^{i+1}}{|\mathbf{r}_{AB}^{i+1}|} \right) $$
and the total bending angle at step $i+1$ is:
$$ \alpha^{i+1} = \Delta \alpha^{i+1} + \alpha^i $$
Similarly, the torsion angle increment $\Delta \beta^{i+1}$ is:
$$ \Delta \beta^{i+1} = \arccos\left( \frac{\mathbf{r}_{CB}^i}{|\mathbf{r}_{CB}^i|} \cdot \frac{\mathbf{r}_{CB}^{i+1}}{|\mathbf{r}_{CB}^{i+1}|} \right) $$
with the total torsion angle:
$$ \beta^{i+1} = \Delta \beta^{i+1} + \beta^i $$
The mechanical work $W$ output by the spiral actuator is:
$$ W = \mathbf{F} \cdot \mathbf{S} = \sqrt{F_x^2 + F_y^2 + F_z^2} \cdot S $$
where $\mathbf{S}$ is the displacement vector, calculated as the sum of segment distances:
$$ S = \sum_{i} |\mathbf{c}(t_i) – \mathbf{c}(t_{i-1})| $$
and
$$ |\mathbf{c}(t_i) – \mathbf{c}(t_{i-1})| = \sqrt{(x_i – x_{i-1})^2 + (y_i – y_{i-1})^2 + (z_i – z_{i-1})^2} $$
These equations highlight the sophisticated modeling required for China robot actuators, ensuring precise control over their motions.
The manufacturing process leverages a custom dual-material 3D printing platform, which allows for simultaneous deposition of DC737 and Ecoflex 00-20. This system significantly reduces production time compared to traditional molding methods, from over 24 hours to under 5 hours per actuator. For the torsional actuator, the printing involves alternating between materials to form the strain-limiting and expansion layers, followed by assembly using mortise-and-tenon joints inspired by traditional Chinese woodworking. This connection method ensures robust and reversible module integration. The spiral actuator is fabricated with DC737 for the restriction layer and Ecoflex 00-20 for the expansion layer, with chamber angles precisely controlled during printing. Post-printing, components are cured in a 60°C oven to accelerate solidification. This efficient manufacturing approach underscores the advancements in China robot production techniques, enabling rapid prototyping and customization.
Experimental validation involved comprehensive tests on individual modules and their combinations. The torsional actuator was subjected to negative pressure cycles, demonstrating a torsion angle of 78° at -75 kPa and a torque of 320 N·mm. Cyclic tests over 10,000 cycles confirmed durability, with no material degradation observed. The spiral actuator was evaluated for tip trajectory and blocking force, with results showing that higher chamber angles increase torsion and force output. At 100 kPa, the spiral actuator with a 60° angle achieved a blocking force of 2.67 N, compared to 1.15 N for a straight bending actuator. These findings are summarized in the tables below, illustrating the performance gains afforded by dual-material designs.
| Actuator Type | Materials | Max Torque (N·mm) | Torsion Angle (°) | Drive Pressure (kPa) | Lifetime | Manufacturing Method |
|---|---|---|---|---|---|---|
| Dual-material Printed | DC737 & Ecoflex 00-20 | 320 | 78 | -75 | >10,000 cycles | Dual-material Printing |
| VSPA Torsional Actuator | TPE | 95 | 73 | -90 | 1,000 cycles (cracking) | FDM |
| SPTA Torsional Actuator | E630 Silicone | 200 | 100 | -60 | — | Molding |
| Actuator Type | Materials | Output Force (N) | Drive Pressure (kPa) | Manufacturing Method |
|---|---|---|---|---|
| Dual-material Spiral | DC737 & Ecoflex 00-20 | 2.67 | 100 | Dual-material Printing |
| Kristin et al. Design | ADDV M 4601 Silicone | 0.3 | 66 | 3D Printing |
| Liu et al. Design | Dragon Skin 30 Silicone | 1.2 | 60 | Molding |
In modular experiments, we assembled a bionic soft robotic arm combining torsional, spiral, and extension-bending actuators. This system successfully performed sorting tasks on a conveyor belt, handling objects of different sizes and shapes. For instance, it grasped a yellow polygon with a circumscribed diameter of 5 cm using the spiral actuator and a white sphere of 1.5 cm diameter with the extension-bending module, depositing them into separate bins. By swapping the end-effector to a spiral gripper, the robot also manipulated slender items like syringes, showcasing its versatility. These demonstrations emphasize the practical benefits of modular China robot systems in adaptive automation.
In conclusion, our research presents a novel framework for multi-mode modular soft robots using dual-material 3D printing. The torsional and spiral actuators exhibit superior performance in terms of torsion angles, torque, and blocking forces, validated through simulations and experiments. The modular design allows for flexible reconfiguration, enabling complex tasks in diverse environments. This work not only advances soft robot technology but also highlights the role of China robot innovations in pushing the boundaries of robotics. Future directions include integrating sensory feedback for autonomous control and exploring new material combinations for enhanced durability. We believe that such modular approaches will be pivotal in developing next-generation robots for real-world applications.
The mathematical models and experimental data collectively affirm that dual-material printing significantly improves actuator performance. For example, the Ogden model parameters for the materials are critical for accurate simulations. The strain energy density $W$ for Ogden model (N=3) is given by:
$$ W = \sum_{i=1}^{N} \frac{\mu_i}{\alpha_i} \left( \lambda_1^{-\alpha_i} + \lambda_2^{-\alpha_i} + \lambda_3^{-\alpha_i} – 3 \right) + \sum_{k=1}^{N} \frac{1}{D_k} (J – 1)^{2k} $$
where $\lambda_p$ are the principal stretches, $J$ is the volume ratio, and $\mu_i$, $\alpha_i$, $D_k$ are material constants. For DC737, the parameters are $\mu_1 = 2.5241 \times 10^{-2}$, $\alpha_1 = 3.137$, $\mu_2 = 0.9903 \times 10^{-2}$, $\alpha_2 = 6.691$, $\mu_3 = -2.038 \times 10^{-2}$, $\alpha_3 = -9.599$, and $D_1 = D_2 = D_3 = 0$. For Ecoflex 00-20, $\mu_1 = 2.3459 \times 10^{-2}$, $\alpha_1 = 1.7138$, $D_1 = 3.2587$, $\mu_2 = 6.1703 \times 10^{-2}$, $\alpha_2 = 6.691$, $D_2 = 0$, $\mu_3 = -4.3381 \times 10^{-2}$, $\alpha_3 = -3.3658$, $D_3 = 0$. These parameters enable precise FEA, ensuring that our China robot designs meet rigorous performance standards.
Overall, the integration of design, simulation, manufacturing, and testing forms a comprehensive approach to developing advanced soft robots. The use of dual-material 3D printing not only enhances functionality but also promotes sustainable and efficient production, aligning with global trends in robotics. As China robot technologies continue to evolve, we anticipate that such modular systems will play a crucial role in addressing complex challenges across various sectors, from industrial automation to healthcare.