Human haptic perception system is complex, involving both cutaneous and kinesthetic receptors. These receptors work together and enable human to perceive the external world. To simulate immersive interaction with virtual objects in virtual reality scenarios haptic devices are desired to reproduce multi-properties of virtual objects, support multi-gestures of human hands to perform fine manipulation, produce haptic stimuli for simultaneously stimulating multi-receptors (including cutaneous and kinesthetic receptors) of human haptic channel, and thus invoke realistic compound haptic sensations. In recent years such multimodal haptic devices have emerged. In this paper, we survey the latest progress on multimodal haptic devices, identify the gaps, and put forward future research directions on the topic.

The soft robotics field investigates biological bodies' movements to develop soft actuation with similar behavior seen in nature. The skeletal muscles' movements are vastly mimicked in soft actuators; however, the contractions of smooth muscles are overlooked in soft robotics. Smooth muscles provide peristaltic contractions to the digestive system, such as the stomach, and their design challenges the limits of soft robot development that simulates digestive organs. We present a novel, bellows-driven soft pneumatic actuator (SPA) with a self-sensing capability that generates linear displacement to simulate a smooth muscle segment in a stomach. This SPA is proposed as a solution for applications such as stomach simulators. The SPA concept, design, fabrication, creep model, and experimental validation are presented in this paper. A lumped viscoelastic model presents the actuator's modeling to predict the SPA's displacement from a known applied pressure. The model is successfully validated, which resulted in a maximum displacement of 20.0 mm with a displacement error of 3%. A sensory system embedded in the SPA measures the displacement, and it is found that a force of 0 to 8.0 N is produced. A polynomial equation calibrates the sensor readings, with a displacement error of 5%. The results show the SPA's capability as a linear soft actuator that can generate a deformation like a smooth muscle segment. To simulate a circular contraction from a stomach with the SPA, we install multi-SPAs in a ring frame that performs contractions. Although the proposed SPA is specifically designed to mimic the smooth muscle, the ring actuator's contractions can be used for other applications such as gripping soft objects.

Aerial manipulation applications involve physical interaction between an unmanned aerial vehicle and its operating environment. This paper presents the novel application of physical coupling between an aerial manipulator and tree towards semi-autonomous canopy sampling. Interactions with unconstrained objects have been studied extensively, however trees are a complex environment with unique and naturally varying mechanical characteristics. Such interactions have not appeared in previous literature so the effects remain unknown, thus warranting this study. First, an aircraft-tree branch interaction model is introduced using known aircraft dynamic modelling methods and a specially developed tree branch mechanical model, representing environmental disturbances to the aircraft. Coupling behavior with a range of canopy branches is investigated in both simulation, and experimentally with the aid of motion capture. The case of interactions with a swaying quasi-rigid tree stem is also explored. These respective studies have revealed station-keeping flight performance whilst coupled with flexible branches, and bounded environmental motion interactions where force closure does not exist. The use of conventional PID control is also validated for branch-coupled flight. Furthermore, a comparison of simulation and experimental results has shown that coupling behavior is adequately represented by mechanical effects captured in the developed tree branch model.