This paper presents a novel condylar hinge for robotic limbs which was inspired by the human knee joint. The ligaments in the human knee joint can be modeled as an inverted parallelogram four-bar mechanism. The knee joint also has a condylar cam mechanism between the femur and tibia bones. The bio-inspired joint mimics the four-bar mechanism and the cam mechanism of the human knee joint. The bio-inspired design has the same desirable features of a human knee joint including compactness, high mechanical advantage, high strength, high stiffness and locking in the upright position. These characteristics are important for robotic limbs where there are often tight space and mass limitations. A prototype hinge joint similar in size to the human knee joint has been designed and tested. Experimental tests have shown that the new condylar hinge joint has superior performance to a pin-jointed hinge in terms of mechanical advantage and stiffness. The prototype hinge has a mechanical advantage that is greater than a pin-jointed hinge by up to 35% which leads to a corresponding reduction in the peak force of the actuator of up to 35% for a squatting movement. The paper also presents a five-step design procedure to produce a combined inverted parallelogram mechanism with a cam mechanism.

Fig. 1. The humanoid robot HUBO and its mechanical design ACL femoral link tibial link PCL θ = 0° θ = 60° θ = 100° Fig. 3. The 4-bar mechanism of the human knee joint R = Rolling S = Sliding Fig. 2. Rolling and sliding between the femur and the tibia in the human knee joint [4]Abstract-This paper presents a bio-inspired design of hinge joint for mobile robots based on the human knee joint. The joint mimics the curved profiles of the femur and tibia bones and also mimics the four-bar motion of the cruciate ligaments. The bioinspired design has the same desirable features of a natural knee joint including compactness, a moving centre of rotation, high strength, high stiffness and locking in the upright position. These characteristics are important for mobile robots where there are often tight space and mass limitations. Numerical analysis and experimental tests have shown that the new hinge joint has superior performance to a pin jointed hinge in terms of stiffness and mechanical advantage.

This paper presents the design and development of a single motor actuated peristaltic worm robot with three segments using a bio-inspired method of locomotion with one actuator that achieves optimised worm like peristaltic motion. Each segment consists of two solid circular disks that have a tendon connected through to the drive mechanism using a Bowden cable and a soft rubber skin that deforms under the compression of the tendon. Our hypothesis that a tuned peristaltic waveform can achieve improved performance of locomotion distance and clamping strength is proven using an initial test platform capable of demonstrating varying waveform types with multiple actuators. Three experiments were undertaken: (i) moving along a flat surface, (ii) moving through a confined tunnel (iii) moving through a confined tunnel whilst pulling a payload. Results from these experiments have identified the optimal parameters for a smart gearbox capable of achieving the same optimal peristaltic waveform signal as the more complex test platform but with only one actuator driving all three worm segments. Unlike other examples of peristaltic worm robots, this example uses a control method embedded within the mechanics of the design removing excessive number of actuators which contributes to miniaturisation, reduces power consumption and simplifies the overall design.

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