In the last few years, there’s been a growing interest in the emerging field of human-centric robots. Such robots involve the close interaction between human beings and robotic manipulation systems. Along with the ability to support a wide range of commercial uses, applications for human-friendly robot designs are notable in manufacturing, home care, medicine, and entertainment.
However, a significant challenge to these applications is safety. How can the robots be enough strong, fast, accurate to perform the needful work, while also being safe for any physical interaction?
Let’s explore the answer today.
- Earlier Approach to Robot Design
Traditionally robots mainly relied on various electromagnetic actuators that offered brilliant controllability but substandard power-to-weight ratios as compared to the pneumatic muscles. Further, they had an inability to exert a sustained force without high transmitting ratios between the load and the motor.
But a high transmitting ratio contributes to high mechanical impedance in the robot arm that doesn’t ensure safety when a biological arm comes in its close proximity. Early efforts to enhance the safety of robot arms all the while maintaining their control performance included powering the joints with cables after relocating the actuators to the base, using high-strength composite materials (inspired by human bones) while designing links to minimize inertia, and utilizing a series of elastic actuators.
Further works employed energy-absorbing layers, variable compliance, and proximity sensors for detecting any impending collisions.
Compact valves in this type of robotic arm resulted in a limitation of performance in steady-state and transient operation. The restricted flow rate also caused significant errors in transient conditions. Their random on-off manner gave rise to unproductive overworking or oscillation in operation, especially at a high pressure.
- Contemporary Approach to Build a Robot
The second-generation roboticists seek to address the discovered limitation. The new robot design incorporates various parallel pneumatic actuators at various joints for increasing the range of available torque motion without becoming extremely bulky. The actuators are usually controlled by an innovative proportional valve system for smooth force control and fast response.
The valves along with several components like mini actuators are housed in a soft and thin-walled structure that offers an ideal combination of robustness and lightweight.
The new design further exploits valves at a high flow rate and delivers a proportional flow control feature. Such a proportional valve subsequently achieves a faster response and a smooth convergence to the optimum pressure.
The first-generation arms utilized a polymer structure as their central bone support. This structure was made by using Selective Laser Sintering or SLS with a glass nylon. In contrast, the new arm is produced using FDM that allows a combination of soft and hard materials and various sensors and other discrete parts that can be integrated into a single heterogeneous structure.
Conclusion
Through this experiment, the roboticists find out that additional pneumatic muscles that are connected in parallel deliver a wide range of motion without affecting the response time and joint torque. Safety simulations utilizing the normalized effective inertia or mass validate the arm safety traits that are somewhat comparable to those of a human arm.
In terms of designing, ongoing work is focused on incorporating several force sensors into the structure and then covering it with a compliant skin to deliver responsive, powerful, realistic, and human-safe robots.
To know more about robot design, feel free to reach the robotic experts at Custom Entertainment Solutions. Call 01.801.410.4869 and visit the official website.
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