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What is just as important as buoyancy for BALLU is a drag. Because the robot is lightweight yet the body takes a large portion, drag force plays a nontrivial role in BALLU’s orientation. Consequently, the drag forces for the transitional and rotational directions with the robot’s X, Y, and Z-axes were calculated using computational fluid dynamics software. Because the lateral distance between two feet keeps the robot from rotating in the roll direction, only the rotations in the pitch and yaw direction are taken as the domain variables for the computation. Considering the rate of change in the pitch and yaw directions that BALLU normally takes, the drag force was computed over ±40deg for the pitch and ±5deg for the yaw angle with the unit speed. When the robot is in a single support phase ( Figure 5C), there is only one supporting force upward, and additionally, the force needs to support the weight of the swing leg, resulting in the height decreasing, and the body sinking down. A neural network is trained as a function approximator for each g. Both networks individually consist of a multilayer perceptron with ELU nonlinear activation functions and ADAM optimizer with MSE (Minimum Square Error) loss and a constant learning rate. Made with helium balloons and lightweight body parts, BALLU (Buoyancy Assisted Lightweight Legged Unit) has the possibility to overcome the aforementioned issues concerning existing robots. The first is safety and inherent stability. Because of the buoyancy provided by the balloons, BALLU is a robot that literally cannot fall down. More importantly, its light parts and soft balloon body can only generate so much momentum and force, allowing it to be operated without worry when there is physical interaction or even collision with young children. This allows BALLU to potentially act in the future as a safe, interactive service robot in the vicinity of people. The second is its cost. BALLU is merely as affordable as many low-cost home appliances. In the long run, this even opens up opportunities for such platforms to act as disposable robots, where a number of them can be easily built and explore unknown environments with the less economic burden. The use of soft materials has the advantage of reducing the forces applied to the colonic wall and consequently diminishing pain and discomfort to the patient during the procedure. Because of the low mechanical stiffness, a soft robot can perform dexterous movements and follows the 3D-shape contours of the colonic lumen without the need of a complex active closed-loop control 20. An additional advantage of using soft materials is the low production costs 21. The body of the robot can be produced by “injection moulding” at a very low cost 22, enabling the robot to be marked as a disposable device and thus avoiding the issues of cleaning, disinfection, and maintenance. This will drastically reduce the health care costs compared to the traditional optical colonoscopy and also the overall acceptability by patients.
Khosraviani M, Jahanshahi M, Farahani M, Bidaki ARZ (2018) Load–frequency control using multi-objective genetic algorithm and hybrid sliding mode control-based SMES. Int J Fuzzy Syst 20(1):280–294 The advantage in using a mini-robot to carry out a colonoscopy is that once inserted through the anus, the device will travel by its intrinsic locomotion capability to the caecum virtually abolishing pain and discomfort, as it avoids pressure on the colonic wall and mesenteric tending by loop formation. In addition, standard conventional optical push colonoscopy is a difficult procedure requiring a long period of training for acquisition of the required level of proficiency for safe expert execution and interpretation 10, 11. Robotic colonoscopy dispenses with this long-proficiency-gain curve, averaging 2–3 years to attain competent and safe caecal intubation. This mini-robot should include a camera in its distal end for visual inspection and instruments for treatment. A soft-tether is necessary for high quality video transmission to an external user console, powering and control of the robot. The tether provides also a safety mechanism for withdrawing the mini-robot in case of malfunction. The friction provided by the tether against the colonic wall is a drag force in the locomotion. To overcome this force a robot needs to provide enough locomotive traction, although this can be challenging considering the small size, light weight of a mini-robot and the slippery colonic mucosa. The more conventional approach to design robots for colonoscopy is essentially by construction of components made of rigid miniaturized mechanical parts 12, 13, 14, 15, 16, 17, 18, 19, which may require expensive high precision machining. Thus, such a mini-rigid robotic colonoscope must be re-usable so that the device will be a financially viable proposition. Even if fully developed, it is most unlikely that it would reduce significantly the costs of screening colonoscopy for colorectal cancer. Drones are perhaps the most well-known type of flying robot. They come in all shapes and sizes, from large military drones to small consumer drones. Additionally, these machines are still expensive for households to adopt. Since many conventional robots use powerful and strong components, they are much higher priced than your average home appliances, and the most affordable and small-scaled quadruped is 2700 USD at the time of this contribution ( Unitree, 2021). The hyperparameters are chosen via grid search to have the least test loss. The list of searched hyperparameters and their candidates are the number of hidden layers h l ∈ 2 0 , 2 1 , ⋯ , 2 7, hidden units h u ∈ 1,2,3,4, and the learning rate α ∈ 0.0001 , 0.0002 , 0.0005 , 0.001 , ⋯ 0.05 , 0.01. As a result, a network with three hidden layers with eight hidden units, respectively, and a learning rate of 0.002 were used.Dirigible: A dirigible has a rigid frame and a semi-rigid envelope. Dirigibles are smaller than blimps and are typically used for military and scientific applications. 2) Airplane robots We trained a planar data-driven walking controller with artificial neural networks using the definition of the state and a set of expert data. In control aspects, it is a convenient choice to take the center of the pelvis link as the origin of the floating body since the pelvis is where all the forces from the legs and the balloons are congregated at. 2.1.3 Legs
Dehghani, H. et al. Semi-autonomous locomotion for diagnostic endoscopy device 1. Journal of Medical Devices 9, 030931, https://doi.org/10.1115/1.4030562 (2015). Huang, C. et al. Miniaturized swimming soft robot with complex movement actuated and controlled by remote light signals. Scientific reports 5, 17414, https://doi.org/10.1038/srep17414 (2015).
Publisher’s Note
While these platforms have shown remarkable progress in technology, essential yet often overlooked aspects that are contributing to their full deployment in close proximity to humans are safety and cost. When they malfunction, the heavyweight and powerful actuation methods could act as a potential cause of serious damage to its surrounding environments and even threaten human lives. In the context of service robots, such robots’ capacity might be redundant for common needs in everyday life but also dangerous. The first noticeable behavior that is important for successful walking is the ability to regulate the body’s height within an interval that BALLU can successfully conduct subsequent motions. In the simulation, we can see that the body height is maintained between 0.58 ∼ 0.70. In the case that such an interval is not preserved, BALLU will exhibit the aforementioned sink-down behavior, leading to an inability to continue walking. Aside from the Z height oscillating within an interval, we can also notice that BALLU does indeed stride forward in the X-direction and its velocity trajectory shows a gradual increase from rest. Hu FJ, Wu G (2020) Distributed error correction of EKF algorithm in multi-sensor fusion localization model. IEEE Access 8:93211–93218. https://doi.org/10.1109/ACCESS.2020.2995170
Tolley, M. T. et al. A resilient, untethered soft robot. Soft Robotics 1, 213–223, https://doi.org/10.1089/soro.2014.0008 (2014). For verification of the proposed locomotion approach, straight walking of about 1.4m is tested with a desired walking speed of 0.18m/ s on the actual hardware.
5 Experiment
Figure 3B depicts the side view of a leg. Decomposed into the radial direction connecting the hip and the foot and the tangential direction, the force applied to the pelvis link through the hip joint is represented as Eqs 5, 6, where fhip;r and fhip;t are the rest of the terms not related to the spring torque of the knee joint, and they are mostly gravitational effects. Since the differences between lfm and ltb are negligible, the spring torque from the knee joint only contributes as a radial force. Gliders are a type of flying robot that does not have any motors or engines. Instead, gliders rely on the wind or other forms of propulsion, such as being launched from a catapult, to stay in the air. Gliders are typically used for leisure and sporting activities, but can also be used for military applications, such as surveillance. Presser trained the system on 2.4 million chess games. "It was really cool to see the chess engine come to life," he says. "I wasn't sure it would work at all." But it did. It's not as good as specially designed chess computers – but it's capable of playing tough matches successfully.
Polter, D. E. Risk of colon perforation during colonoscopy at baylor university medical center. In Baylor University Medical Center Proceedings, vol. 28, 3–6 (Taylor & Francis, 2015). During a colonoscopy, air or gas is used to inflate and expand the colonic lumen with an internal pressure up to 7.6 kPa 47, 48, which is higher than the balloon activation pressure required in SPID. The pressure of the balloon against the colonic wall is the result of the internal air pressure ( P B) minus the elastomer mechanical pressure ( P E). This produces an external pressure on the colon wall, which is much lower than the pressure pain threshold encountered during standard colonoscopy. SPA designThis is one of the pitfalls of "reinforcement learning", in which an AI ends up devising a wrong-headed strategy based on what it encounters in its environment. The AI doesn't know why it succeeded, it can only base its actions on learned associations. A bit like early human cultures that began to associate rituals with changes in the weather, for example. Cheung, E., Karagozler, M. E. & Sitti, M. A new endoscopic microcapsule robot using beetle inspired microfibrillar adhesives. In Proceedings, 2005 IEEE/ASME International Conference on Advanced Intelligent Mechatronics, 551–557, https://doi.org/10.1109/AIM.2005.1511040 (2005). Hybrid balloon: A hybrid balloon robot is a combination of hot air and a gas balloon. These are relatively new technology and are typically helpful for long-duration flights. Norton, J. et al. Rollerball: A mobile robot for intraluminal locomotion. In 2016 6th IEEE International Conference on Biomedical Robotics and Biomechatronics (BioRob), 254–259, https://doi.org/10.1109/BIOROB.2016.7523634 (2016).
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