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PubMed2003

The emergence of communication in evolutionary robots.

Evolutionary robotics is a biologically inspired approach to robotics that is advantageous to studying the evolution of communication. A new model for the emergence of communication is developed and tested through various simulation experiments. In the first simulation, the emergence of simple signalling behaviour is studied. This is used to investigate the inter-relationships between communication abilities, namely linguistic production and comprehension, and other behavioural skills. The model supports the hypothesis that the ability to form categories from direct interaction with an environment constitutes the grounds for subsequent evolution of communication and language. In the second simulation, evolutionary robots are used to study the emergence of simple syntactic categories, e.g. action names (verbs). Comparisons between the two simulations indicate that the signalling lexicon emerged in the first simulation follows the evolutionary pattern of nouns, as observed in related models on the evolution of syntactic categories. Results also support the language-origin hypothesis on the fact that nouns precede verbs in both phylogenesis and ontogenesis. Further extensions of this new evolutionary robotic model for testing hypotheses on language origins are also discussed.

Adaptation, Physiological↗

PubMed2003

Evolving controllers for a homogeneous system of physical robots: structured cooperation with minimal sensors.

We report on recent work in which we employed artificial evolution to design neural network controllers for small, homogeneous teams of mobile autonomous robots. The robots were evolved to perform a formation-movement task from random starting positions, equipped only with infrared sensors. The dual constraints of homogeneity and minimal sensors make this a non-trivial task. We describe the behaviour of a successful system in which robots adopt and maintain functionally distinct roles in order to achieve the task. We believe this to be the first example of the use of artificial evolution to design coordinated, cooperative behaviour for real robots.

Adaptation, Physiological↗

PubMed2006

Optimization of a spherical mechanism for a minimally invasive surgical robot: theoretical and experimental approaches.

With a focus on design methodology for developing a compact and lightweight minimally invasive surgery (MIS) robot manipulator, the goal of this study is progress toward a next-generation surgical robot system that will help surgeons deliver healthcare more effectively. Based on an extensive database of in-vivo surgical measurements, the workspace requirements were clearly defined. The pivot point constraint in MIS makes the spherical manipulator a natural candidate. An experimental evaluation process helped to more clearly understand the application and limitations of the spherical mechanism as an MIS robot manipulator. The best configuration consists of two serial manipulators in order to avoid collision problems. A complete kinematic analysis and optimization incorporating the requirements for MIS was performed to find the optimal link lengths of the manipulator. The results show that for the serial spherical 2-link manipulator used to guide the surgical tool, the optimal link lengths (angles) are (60 degrees, 50 degrees). A prototype 6-DOF surgical robot has been developed and will be the subject of further study.

Computer-Aided Design↗

PubMed2005

Precise robot-assisted guide positioning for distal locking of intramedullary nails.

This paper presents a novel image-guided robot-based system to assist orthopedic surgeons in performing distal locking of long bone intramedullary nails. The system consists of a bone-mounted miniature robot fitted with a drill guide that provides rigid mechanical guidance for hand-held drilling of the distal screws' pilot holes. The robot is automatically positioned so that the drill guide and nail distal locking axes coincide, using a single fluoroscopic X-ray image. Since the robot is rigidly attached to the intramedullary nail or bone, no leg immobilization or real-time tracking is required. We describe the system and protocol and present a method for accurate and robust drill guide and nail hole localization and registration. The in vitro system accuracy experiments for fronto-parallel viewing show a mean angular error of 1.3 degrees (std = 0.4 degrees ) between the computed drill guide axes and the actual locking holes axes, and a mean 3.0 mm error (std = 1.1 mm) in the entry and exit drill point, which is adequate for successfully locking the nail.

Algorithms↗

PubMed2003

Information conveyed through brain-control: cursor versus robot.

Microwire electrode arrays were implanted in the motor and premotor cortical areas of rhesus macaques. The recorded activity was used to control the three-dimensional movements of a virtual cursor and of a robotic arm in real time. The goal was to move the cursor or robot to one of eight targets. Average information conveyed about the intended target was calculated from the observed trajectories at 30-ms intervals throughout the movements. Most of the information about intended target was conveyed within the first second of the movement. For the brain-controlled cursor, the instantaneous information transmission rate was at its maximum at the beginning of each movement (averaged 4.8 to 5.5 bits/s depending on the calculation method used). However, this instantaneous rate quickly slowed down as the movement progressed and additional information became redundant. Information was conveyed more slowly through the brain-controlled robot due to the dynamics and noise of the robot system. The brain-controlled cursor data was also used to demonstrate a method for optimizing information transmission rate in the case where repeated cursor movements are used to make long strings of sequential choices such as in a typing task.

Animals↗

PubMed2005

Customized interactive robotic treatment for stroke: EMG-triggered therapy.

A system for electromyographic (EMG) triggering of robot-assisted therapy (dubbed the EMG game) for stroke patients is presented. The onset of a patient's attempt to move is detected by monitoring EMG in selected muscles, whereupon the robot assists her or him to perform point-to-point movements in a horizontal plane. Besides delivering customized robot-assisted therapy, the system can record signals that may be useful to better understand the process of recovery from stroke. Preliminary experiments aimed at testing the proposed system and gaining insight into the potential of EMG-triggered, robot-assisted therapy are reported.

Aged↗

PubMed2004

Generating high-speed dynamic running gaits in a quadruped robot using an evolutionary search.

Over the past several decades, there has been a considerable interest in investigating high-speed dynamic gaits for legged robots. While much research has been published, both in the biomechanics and engineering fields regarding the analysis of these gaits, no single study has adequately characterized the dynamics of high-speed running as can be achieved in a realistic, yet simple, robotic system. The goal of this paper is to find the most energy-efficient, natural, and unconstrained gallop that can be achieved using a simulated quadrupedal robot with articulated legs, asymmetric mass distribution, and compliant legs. For comparison purposes, we also implement the bound and canter. The model used here is planar, although we will show that it captures much of the predominant dynamic characteristics observed in animals. While it is not our goal to prove anything about biological locomotion, the dynamic similarities between the gaits we produce and those found in animals does indicate a similar underlying dynamic mechanism. Thus, we will show that achieving natural, efficient high-speed locomotion is possible even with a fairly simple robotic system. To generate the high-speed gaits, we use an efficient evolutionary algorithm called set-based stochastic optimization. This algorithm finds open-loop control parameters to generate periodic trajectories for the body. Several alternative methods are tested to generate periodic trajectories for the legs. The combined solutions found by the evolutionary search and the periodic-leg methods, over a range of speeds up to 10.0 m/s, reveal "biological" characteristics that are emergent properties of the underlying gaits.

Algorithms↗

PubMed2005

Homography-based visual servo regulation of mobile robots.

A monocular camera-based vision system attached to a mobile robot (i.e., the camera-in-hand configuration) is considered in this paper. By comparing corresponding target points of an object from two different camera images, geometric relationships are exploited to derive a transformation that relates the actual position and orientation of the mobile robot to a reference position and orientation. This transformation is used to synthesize a rotation and translation error system from the current position and orientation to the fixed reference position and orientation. Lyapunov-based techniques are used to construct an adaptive estimate to compensate for a constant, unmeasurable depth parameter, and to prove asymptotic regulation of the mobile robot. The contribution of this paper is that Lyapunov techniques are exploited to craft an adaptive controller that enables mobile robot position and orientation regulation despite the lack of an object model and the lack of depth information. Experimental results are provided to illustrate the performance of the controller.

Algorithms↗

PubMed2005

A layered goal-oriented fuzzy motion planning strategy for mobile robot navigation.

Most conventional motion planning algorithms that are based on the model of the environment cannot perform well when dealing with the navigation problem for real-world mobile robots where the environment is unknown and can change dynamically. In this paper, a layered goal-oriented motion planning strategy using fuzzy logic is developed for a mobile robot navigating in an unknown environment. The information about the global goal and the long-range sensory data are used by the first layer of the planner to produce an intermediate goal, referred to as the way-point, that gives a favorable direction in terms of seeking the goal within the detected area. The second layer of the planner takes this way-point as a subgoal and, using short-range sensory data, guides the robot to reach the subgoal while avoiding collisions. The resulting path, connecting an initial point to a goal position, is similar to the path produced by the visibility graph motion planning method, but in this approach there is no assumption about the environment. Due to its simplicity and capability for real-time implementation, fuzzy logic has been used for the proposed motion planning strategy. The resulting navigation system is implemented on a real mobile robot, Koala, and tested in various environments. Experimental results are presented which demonstrate the effectiveness of the proposed fuzzy navigation system.

Algorithms↗

PubMed2006

Robustly stable adaptive control of a tandem of master-slave robotic manipulators with force reflection by using a multiestimation scheme.

The problem of controlling a tandem of robotic manipulators composing a teleoperation system with force reflection is addressed in this paper. The final objective of this paper is twofold: 1) to design a robust control law capable of ensuring closed-loop stability for robots with uncertainties and 2) to use the so-obtained control law to improve the tracking of each robot to its corresponding reference model in comparison with previously existing controllers when the slave is interacting with the obstacle. In this way, a multiestimation-based adaptive controller is proposed. Thus, the master robot is able to follow more accurately the constrained motion defined by the slave when interacting with an obstacle than when a single-estimation-based controller is used, improving the transparency property of the teleoperation scheme. The closed-loop stability is guaranteed if a minimum residence time, which might be updated online when unknown, between different controller parameterizations is respected. Furthermore, the analysis of the teleoperation and stability capabilities of the overall scheme is carried out. Finally, some simulation examples showing the working of the multiestimation scheme complete this paper.

Algorithms↗

PubMed2004

Evaluating alternative gait strategies using evolutionary robotics.

Evolutionary robotics is a branch of artificial intelligence concerned with the automatic generation of autonomous robots. Usually the form of the robot is predefined and various computational techniques are used to control the machine's behaviour. One aspect is the spontaneous generation of walking in legged robots and this can be used to investigate the mechanical requirements for efficient walking in bipeds. This paper demonstrates a bipedal simulator that spontaneously generates walking and running gaits. The model can be customized to represent a range of hominoid morphologies and used to predict performance parameters such as preferred speed and metabolic energy cost. Because it does not require any motion capture data it is particularly suitable for investigating locomotion in fossil animals. The predictions for modern humans are highly accurate in terms of energy cost for a given speed and thus the values predicted for other bipeds are likely to be good estimates. To illustrate this the cost of transport is calculated for Australopithecus afarensis. The model allows the degree of maximum extension at the knee to be varied causing the model to adopt walking gaits varying from chimpanzee-like to human-like. The energy costs associated with these gait choices can thus be calculated and this information used to evaluate possible locomotor strategies in early hominids.

Animals↗

PubMed2006

Robotic urological surgery in patients with prior abdominal operations is not associated with increased complications.

BACKGROUND: The da Vinci Surgical Robotic System is being increasingly used to perform complex urological operations by minimally invasive techniques. Prior abdominal surgery associated with intra-abdominal adhesions may complicate robotic surgery. METHODS: We used a cohort of consecutive 49 patients undergoing a variety of robotic urological procedures at our institution to study the impact of prior abdominal operations on early perioperative complications. RESULTS: A total of 21/49 (43%) patients (Group A) had no history of prior abdominal surgery and the rest 28/49 (57%; Group B) had undergone prior abdominal surgery. The incidence of peritoneal adhesions was significantly higher in patients with prior abdominal surgery compared to the rest of the cohort, 54% versus 10% (P=0.002). The median operative time, estimated blood loss, postoperative drop in hemoglobin, time to hospital discharge, postoperative narcotic analgesic use and postoperative complication rate between group A and group B were not statistically different. The overall perioperative complication rate for the entire cohort was 14.3%, with 6-8% of complications occurring in each of the two groups (P=1.0). Comparative subset analysis of 28 patients in Group B, 15 (54%) and 13 (46%) with or without intra-abdominal adhesions did not reveal a significant difference in perioperative complication rates either. However, operative time was longer in patients with intra-abdominal adhesions compared to patients without, median of 590 (281-922) and 434 (153-723) min respectively, although not statistically significant (P=0.059). CONCLUSION: Our study demonstrates that robotic urological surgery can be performed in patients with prior abdominal surgery without increased perioperative complications.

Abdominal Cavity↗

PubMed2006

Team-based approach reduces learning curve in robot-assisted laparoscopic radical prostatectomy.

AIM: We assessed the team approach in reducing the learning curve during our 2-year experience transiting from open to robot-assisted laparoscopic radical prostatectomy (rLRP). METHODS: A team of three urologists progressed through assistant phase to console phase to obtain competency in robotic prostatectomy. One hundred patients underwent rLRP by this team using the da Vinci robotic surgical system from 1 February 2003 to 15 May 2005. RESULTS: The immediate perioperative outcome was divided into three corresponding time frames and the results demonstrated gradual improvement in outcome parameters. The mean set-up time and dissection time were 24+/-14 min and 182+/-52 min, respectively. The mean perioperative blood loss was 272+/-240 mL, and 7% of patients (n=7) required blood transfusion. The mean duration of bladder catheterization was 8.4+/-4.1 days, and mean hospital stay was 2.9+/-1.6 days. There was no perioperative mortality or conversion to open radical prostatectomy. Major complications (4%) included urethrovesical leak requiring re-operation, postoperative cerebrovascular accident, and transient ureteric obstruction. Minor complications (7%) included minor urethrovesical leak, bladder neck stenosis, and urinary tract infection. Mean follow up was 6.6+/-5.0 months. Pathological assessment showed pT2 disease in 55% and pT3 in 45% of specimens. CONCLUSIONS: A team-based approach to robot-assisted LRP helped to reduce the learning curve of the procedure for individual surgeons and continued to show significantly lower perioperative blood loss, transfusion requirements and postoperative pain compared to open radical retropubic prostatectomy.

Follow-Up Studies↗

PubMed2004

Robot-assisted laparoscopic adrenalectomy: preliminary UK results.

OBJECTIVE: To describe the results of our first two cases of laparoscopic adrenalectomy using the da Vinci surgical system (Intuitive Surgical, Inc., Mountain View, CA, USA). PATIENTS AND METHODS: Amongst 75 robot-assisted procedures performed at our institution, two patients underwent robot-assisted laparoscopic adrenalectomy. The set-up time, procedure time, hospital stay, complications and outcomes were recorded. RESULTS: Both operations were completed successfully using the robot; the mean (range) set-up time was 31 (25-37) min and mean procedure time 118.5 (107-130) min. One patient had a postoperative pulmonary embolus and was discharged 5 days after surgery; the second patient was discharged after 3 days. There were no intraoperative complications; both patients were well at the 1-year follow-up. CONCLUSIONS: Robot-assisted laparoscopic adrenalectomy is technically feasible and can be conducted efficiently and safely with the da Vinci surgical system.

Adenoma↗

PubMed2004

The technique of apical dissection of the prostate and urethrovesical anastomosis in robotic radical prostatectomy.

OBJECTIVE: To describe the technique of dissecting the apex of the prostate and a modified single running-suture urethrovesical anastomosis in patients undergoing robot-assisted radical prostatectomy for organ-confined prostate cancer. PATIENTS AND METHODS: Over 550 robot-assisted radical prostatectomies have been undertaken using Vattikuti Institute Prostatectomy (VIP) technique in patients with localized carcinoma of the prostate. We present a critical analysis of the first 120 procedures by one surgeon (M.M.) at our institution using this newly developed technique of urethrovesical anastomosis preceded by dissecting the apex of the prostate. RESULTS: The mean time for the urethrovesical anastomosis was 13 min. All but 24 patients had their catheter removed 4 days after surgery, as indicated by a cystogram. The catheter was removed successfully at 7 days in the remaining 24 patients who had a mild leak on cystography. Two patients had urinary retention within a week of removing the catheter and had to be re-catheterized. Continence was evaluated using standardized criteria before and after the procedure. The patients also replied to a mailed validated questionnaire survey; 96% were continent at 3 months and the remaining 4% used a thin pad for security. CONCLUSIONS: We report a technique of dissecting the apex of the prostate and prostatovesical junction for dividing the bladder neck, and a modified single running-suture urethrovesical anastomosis, in patients undergoing robot-assisted radical prostatectomy for organ-confined cancer of the prostate. The same principles can also be applied for the anastomosis during pure laparoscopic procedures and for urethro-neovesical anastomosis in patients undergoing robotic radical cystoprostatectomy for carcinoma of the bladder.

Anastomosis, Surgical↗

PubMed2006

Laparoscopic robotic-assisted management of pelvi-ureteric junction obstruction in patients with horseshoe kidneys: technique and 1-year follow-up.

OBJECTIVE: To report our experience with laparoscopic robotic-assisted management of pelvi-ureteric junction obstruction (PUJO) in patients with horseshoe kidneys. PATIENTS AND METHODS: Between January 2002 and May 2003, two men and a woman with horseshoe kidneys (mean age 44.6 years) had laparoscopic dismembered pyeloplasty with robotic assistance for PUJO with no division of the isthmus. Two patients had renal stones which were extracted during surgery. None of the patients had had previous abdominal surgery. RESULTS: The mean operative duration was 148.3 min, the mean estimated blood loss was <100 mL and the mean hospital stay was 7.6 days. Renal function was preserved in all three patients during the immediate and long-term follow-up as measured by intravenous urography. The three patients had durable clinical and radiographic success during a mean follow-up of 21 months. One patient needed complementary extracorporeal shockwave lithotripsy, and one had an episode of pyelonephritis, which was treated successfully. There were no other significant complications before or after surgery. CONCLUSION: Laparoscopic robotic-assisted pyeloplasty for horseshoe kidney is safe and feasible, offering the advantages of minimally invasive surgical procedures with enhanced laparoscopic skills related to the use of the robot.

Adult↗

PubMed2001

Experimental study of transurethral robotic laser resection of the prostate using the LaserTrode lightguide.

A longer operating time and steeper learning curve in mastering the techniques for transurethral laser resection of the prostate are the main problems faced by surgeons in addition to the existing ones in standard transurethral resection of the prostate (TURP). However, these disadvantages can be alleviated with the introduction of a treatment procedure designed and developed based on an integrated system of computer, robotics and laser technology. In vitro experiments were carried out to determine variables affecting the vaporization and coagulation lesions, in order to study the effectiveness and feasibility of robotics for this procedure. Human cadaveric prostates and fresh tauted chicken breast tissues were irradiated with different parameters using the LaserTrode lightguide in contact with the tissue. The effects of irrigant flow rate, fiber/tissue angle of inclination, number of passes, direction, speed and power of lase on the volume of tissue vaporized and coagulated, were assessed. The final phase of the experiments includes executing the robotic motion plan for the laser resection procedure on the human cadaveric prostate tissue embedded in an anatomically alike prostate phantom. It was concluded from our study that power and speed of lase are the most significant parameters influencing the volume of the vaporized and coagulated lesion. Comparison of removal rate using the new treatment procedure of robotic laser resection of the prostate with TURP and HoLRP evinced equivalent results.

Animals↗

PubMed2005

Feasibility of four-dimensional conformal planning for robotic radiosurgery.

Organ motion can have a severe impact on the dose delivered by radiation therapy, and different procedures have been developed to address its effects. Conventional techniques include breath hold methods and gating. A different approach is the compensation for target motion by moving the treatment beams synchronously. Practical results have been reported for robot based radiosurgery, where a linear accelerator mounted on a robotic arm delivers the dose. However, not all organs move in the same way, which results in a relative motion of the beams with respect to the body and the tissues in the proximity of the tumor. This relative motion can severely effect the dose delivered to critical structures. We propose a method to incorporate motion in the treatment planning for robotic radiosurgery to avoid potential overdosing of organs surrounding the target. The method takes into account the motion of all considered volumes, which is discretized for dose calculations. Similarly, the beam motion is taken into account and the aggregated dose coefficient over all discrete steps is used for planning. We simulated the treatment of a moving target with three different planning methods. First, we computed beam weights based on a 3D planning situation and simulated treatment with organ motion and the beams moving synchronously to the target. Second, beam weights were computed by the 4D planning method incorporating the organ and beam motion and treatment was simulated for beams moving synchronously to the target. Third, the beam weights were determined by the 4D planning method with the beams fixed during planning and simulation. For comparison we also give results for the 3D treatment plan if there was no organ motion and when the plan is delivered by fixed beams in the presence of organ motion. The results indicate that the new 4D method is preferable and can further improve the overall conformality of motion compensated robotic radiosurgery.

Biophysical Phenomena↗