Bhargav Mitra

Toward anthropomimetic robotics: Development, simulation, and control of a musculoskeletal torso

Anthropomimetic robotics differs from conventional approaches by capitalizing on the replication of the inner structures of the human body, such as muscles, tendons, bones, and joints. Here we present our results of more than three years of research in constructing, simulating, and, most importantly, controlling anthropomimetic robots. We manufactured four physical torsos, each more complex than its predecessor, and developed the tools required to simulate their behavior. Furthermore, six different control approaches, inspired by classical control theory, machine learning, and neuroscience, were developed and evaluated via these simulations or in small-scale setups. While the obtained results are encouraging, we are aware that we have barely exploited the potential of the anthropomimetic design so far. But, with the tools developed, we are confident that this novel approach will contribute to our understanding of morphological computation and human motor control in the future.

Towards anthropomimetic robotics: Development, simulation, and control of a musculoskeletal torso

Abstract Anthropomimetic robotics differs from conventional approaches by capitalizing on the replication of the inner structures of the human body, such as muscles, tendons, bones, and joints. Here we present our results of more than three years of research in constructing, simulating, and, most importantly, controlling anthropomimetic robots. We manufactured four physical torsos, each more complex than its predecessor, and developed the tools required to simulate their behavior. Furthermore, six different control approaches, inspired by classical control theory, machine learning, and neuroscience, have been developed and evaluated via these simulations or in small-scale setups. While the obtained results are encouraging, we are aware that we have barely exploited the potential of the anthropomimetic design so far. But, with the tools developed, we are confident that this novel approach will contribute to our understanding of morphological computation and human motor control in the future.

Illumination invariant stationary object detection

A real-time system for the detection and tracking of moving objects that becomes stationary in a restricted zone. A new pixel classification method based on the segmentation history image is used to identify stationary objects in the scene. These objects are then tracked using a novel adaptive edge orientation-based tracking method. Experimental results have shown that the tracking technique gives more than a 95% detection success rate, even if objects are partially occluded. The tracking results, together with the historic edge maps, are analysed to remove objects that are no longer stationary or are falsely identified as foreground regions because of sudden changes in the illumination conditions. The technique has been tested on over 7 h of video recorded at different locations and time of day, both outdoors and indoors. The results obtained are compared with other available state-of-the-art methods.

Using the Microsoft Kinect to model the environment of an anthropomimetic robot

The control of compliantly actuated anthropomimetic robots with complex and multiarticular joints, such as those developed within the ECCEROBOT project, is extremely challenging. We are approaching the problem by using a physics engine to run a highly detailed simulation of such a robot’s structure and dynamic behaviour, and then searching for sequences of motor activations that will achieve particular goals. This requires the simulated robot to be situated accurately in a physics-based representation of its environment which includes the object with which it is to interact. In this paper we present our environmental sensing and modelling scheme which uses data from a single headmounted Kinect sensor to provide and locate the environmental model, and to identify and locate the target object accurately in the presence of significant motion blur.

An optical space domain volume holographic correlator

We propose a novel space domain volume holographic correlator system. One of the limitations of conventional correlators is the bandwidth limits imposed by updating the filter and the readout speed of the CCD. The volume holographic correlator overcomes these by storing a large number of filters that can be interrogated simultaneously. By using angle multiplexing, the match can be read out onto a high speed linear array of sensors. A scanning window can be used to implement shift invariance, thus, making the system operate like a space domain correlator. The space domain correlation method offers an advantage over the frequency domain correlator in that the correlation filter no longer has shift invariance imposed on it since the kernel can be modified depending on its position. This maybe used for normalising the kernel or imposing some non-linearity in an attempt to improve performance. However, one of the key advantages of the frequency domain method is lost using this technique, namely the speed of the computation. A large kernel space-domain correlation, performed on a computer, will be very slow compared to what is achievable using a 4f optical correlator. We propose a method of implementing this using the scanning holographic memory based correlator.

On a method to eliminate moving shadows in video sequences

We present a simple computational model that works in the RGB colour space to detect moving shadow pixels in video sequences of indoor scenes, illuminated in each case by an incandescent source. A channel ratio test for shadows cast on some common indoor surfaces is proposed that can be appended to the developed scheme so as to reduce the otherwise high false detection rate. The core method, based on a Lambertian hypothesis, has been adapted to work well for near-matte surfaces by suppressing highlights. The results reported, based on an extensive data analysis conducted on some of the crucial parameters involved in the model, not only bring out the subtle details of the parameters, but also remove the ad hoc nature of the chosen thresholds to a certain extent. The method has been tested on various indoor video sequences; the results obtained indicate that it can be satisfactorily used to mark or eliminate the strong portion of the foreground shadow region.

Performance Analysis of a Modified Moving Shadow Elimination Method Developed for Indoor Scene Activity Tracking

Moving shadow detection is an important step in automated robust surveillance systems in which a dynamic object is to be segmented and tracked. Rejection of the shadow region significantly reduces the erroneous tracking of non-target objects within the scene. A method to eliminate such shadows in indoor video sequences has been developed by the authors. The objective has been met through the use of a pixel-wise shadow search process that utilizes a computational model in the RGB colour space to demarcate the moving shadow regions from the background scene and the foreground objects. However, it has been observed that the robustness and efficiency of the method can be significantly enhanced through the deployment of a binary-mask based shadow search process. This, in turn, calls for the use of a prior foreground object segmentation technique. The authors have also automated a standard foreground object segmentation technique through the deployment of some popular statistical outlier-detection based strategies. The paper analyses the performance i.e. the effectiveness as a shadow detector, discrimination potential, and the processing time of the modified moving shadow elimination method on the basis of some standard evaluation metrics.

Advanced MagLev Propulsion System and its Economic Impact

*† ‡ § ** Rocketry can be considered as the enabler of more or less all space technologies. Its ability to deliver satellites at reasonable costs has made us dependent on this delivery mechanism to fulfill our daily tasks, be it communications, satellite navigation, visual entertainment or weather forecasting. Scientifically, advances in rocketry have enabled us to view the ever-expanding universe. Its most significant impact however comes in the form of manned spaceflight vehicles such as the Space Shuttle, Soyuz and now Space Ship One. A significant development is greater commercialization of manned rocketry, helping provide widespread access to space. Most rocket designs use some form of chemical propellant as their dominant fuel source, primarily as combustion of these propellants provides ample power at limited costs. However, over the last decade as the price of chemical propellants continues to soar and their detrimental effect on our environment comes to light, there has been significant interest in developing an alternative propulsion mechanism to power a new generation of space vehicles. There is now, more than ever, the need for a greener technology, which is capable of providing a similar power output without compromising on safety and reliability. This paper proposes the use of magnetic levitation and propulsion within a vacuum chamber as that technology. It aims to prove that such a system, located strategically close to the equator, is capable of providing adequate thrust to future space vehicles, be it for space tourism or exploration. Although, inception and creation of such a system may seem radical and expensive, the long-term costs are relatively lower than current day systems.

Door surveillance using edge map-based Harris corner detector and active contour orientation

Accurately generating an alarm for a moving door is a precondition for tracking, recognizing and segmenting objects or people entering or exiting the door. The challenge of generating an alarm when a door event occurs is difficult when dealing with complex doors, moving cameras, objects moving or an obscured entrance of the door, together with the presence of varying illumination conditions such as a door-way light being switched on. In this paper, we propose an effective method of tracking the door motion using edge-map information contained within a localised region at the top of the door. The region is located where the top edge of the door displaces every time the door is opened or closed. The proposed algorithm uses the edge-map information to detect the moving corner in the small windowed area with the help of a Harris corner detector. The moving corner detected in the selected region gives an exact coordinate of the door corner in motion, thus helping in generating an alarm to signify that the door is being opened or closed. Additionally, due to the prior selection of the small region, the proposed method nullifies the adverse effects mentioned above and helps prevent different objects that move in front of the door affecting its efficient tracking. The proposed overall method also generates an alarm to signify whether the door was displaced to provide entry or exit. To do this, an active contour orientation is computed to estimate the direction of motion of objects in the door area when an event occurs. This information is used to distinguish between objects and entities entering or exiting the door. A Hough transform is applied on a specific region in the frame to detect a line, which is used to perform error correction to the selected windows. The detected line coordinates are used to nullify the effects of a moving camera platform, thus improving the robustness of the results. The developed algorithm has been tested on all the Door Zone video sequences contained with the United Kingdom Home Office i-LIDs dataset, with promising results.

Efficient denoising of images using a nonaggressive median filtering scheme

The paper proposes a nonaggressive median filtering scheme, with two settings, that can be used to restore images moderately corrupted with either of the two distinct types of impulse noise—fixed-valued and random-valued. The scheme benefits from the fact that its design requires neither the difficult selection of optimal image-data dependent threshold(s), nor any kind of prior training. The filter has been tested on various standard images contaminated with both varieties of impulse noise (not added simultaneously); the results obtained strongly validate the good performance of the process. The proposed approach fulfils all the requirements needed for use as a real-time video-processing component.