Another interesting point is that the slopes are not symmetric when the pelvis moves up and down and implies BALLU’s unique walking dynamics. It comes from the fact that the velocity in X-direction periodically goes up and down. This behavior becomes more obvious later in the hardware test, and the velocity even goes down to the negative. The difference is due to the reality gap including the calibration of the knee joint’s initial position, errors in the mass distribution, and the approximation error of drag force. The corresponding phase plot is shown in Figures 8E,F. Similarly, as BALLU starts from rest, we can observe that the general circular shape of the limit cycle starts small in the earlier state ( Figure 8E) but gradually expands until it converges in the latter stage ( Figure 8F). This behavior is in parallel with that seen in previous works Ahn and Hong, 2020. 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).

College student calls out university for spending money on

BALLU is a unique bipedal robot that, because of the external buoyancy force and its simple configuration, exhibits a distinct locomotion behavior different from conventional bipeds. When a first-time operator is tasked to trigger each leg individually and make the robot walk, it can respond with non-intuitive behaviors. The most noticeable is the turning in the yaw direction, where because of the underactuation and the mass of the legs relative to the entire body, the body’s yaw orientation can change significantly depending on the duration that the robot is in the single stance phase. Furthermore, as the body oscillates up and down during locomotion and since buoyancy and drag distort the speed at which the robot moves, BALLU looks as if it is slowly striding in space. Such non-intuitive and unconventional behavior inherent by the design calls for a detailed analysis of the platform’s motions to potentially leverage them for control. 3.1 Challenge Radio-based indoor GPS helps to locate each BionicSwift unit so that each has spatial awareness and can fly in a coordinated pattern. The setup involves a few radio modules mounted in a given space, and each bird has a radio marker that sends signals to the bases. Liu Y, Dong HB, Lohse N, Petrovic S (2016) A multi-objective genetic algorithm for optimization of energy consumption and shop floor production performance. Int J Prod Econ 179:259–272 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).

3 Motion Analysis

During remote control, there are a few ways to control the forward speed. One way is to control the swing time. Since a leg takes a great part of BALLU’s total weight, after passing the nadir of its swing, the whole body gains velocity from the moment of the swing leg. The closer the leg swings to the apex, the greater forward speed the body gains when it exits the single support phase. However, the length of a single support phase directly affects the following footstep position, which influences the states in the subsequent phases. 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.

BALLU2: A Safe and Affordable Buoyancy Assisted Biped

Nonetheless, small fluctuations can be observed in the limit cycle. There can be a couple of explanations for such inconsistency. The first cause is the distribution of the training data. The neural network is trained considering that the expert data is optimal. However, the expert data does not form a perfect limit cycle but, in fact, rather makes a qualitative periodic trajectory. Therefore, it can be expected for the neural net to generate a periodic motion overall as the expert data does but not to make a perfectly overlapped limit cycle. Colorectal cancer (CRC) is the third most common cause of cancer worldwide 1. Regular screening of the asymptomatic population can drastically reduce the mortality rate (5-year survival rate above 90% in case of early, stage I, diagnosis) 2. CRC screening involves several procedures 3, 4, although the gold standard remains optical colonoscopy 5 because of its high sensitivity in detecting small or sessile polyps 2 and low false negative rate 6. Colonoscopy is performed with a flexible 1.6 meter long colonoscope by a trained colonoscopist. A colonoscope is a semi-flexible tube with 2 cable-driven degrees of freedom (DOFs) in the tip (pitch and yaw angles), which are controlled by an external manual handle. Two additional DOFs are provided by rotating the colonoscope through its handle and by pushing the instrument through the anus. This pushing force is required to introduce and navigate the colonoscope inside of the lumen of the colon to reach the caecum (top expanded section). During this procedure, the long and passive tube is pushed against the colonic wall, inducing pain and discomfort for the patient 7, 8. For this reason, colonoscopy for screening and diagnosis of symptomatic diseases may often require sedation and analgesia. Aside from discomfort, rare instances of colonic perforation 9 requiring emergency surgery to prevent peritonitis remain a concern. Cleaning and chemical sterilization of colonoscopes are necessary as the device is expensive, non-disposable and requires periodic servicing and maintenance to ensure a continued optimal function. Kozarek, R. A., Earnest, D. L., Silverstein, M. E. & Smith, R. G. Air-pressure-induced colon injury during diagnostic colonoscopy. Gastroenterology 78, 7–14, https://doi.org/10.1016/0016-5085(80)90185-7 (1980).In addition, the above results imply that concentrating weight on the feet is more advantageous than putting weight on the pelvis. While those two results show similar pelvis trajectories, the increment on feet is four times larger than that on the pelvis, and the controller fails if the weights are increased further in both cases. This proves once again our design approach to allocate most of the parts on the feet (Section 2.1). With its unique structure, the multi-balloon flexible robot can simulate different body types very well, and has been well applied in clothing design, production and sales [ 1, 2, 3]. The accuracy and efficiency of the copying depends on the control effect of multiple airbag internal motors on the outer wall of the airbag. Therefore, it is of great significance to study the multi-balloon cooperative control strategy with high efficiency and keen precision. 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.