Coordination of multiple robot arms

Kinematic resolved-rate control from one robot arm is extended to the coordinated control of multiple robot arms in the movement of an object. The structure supports the general movement of one axis system (moving reference frame) with respect to another axis system (control reference frame) by one or more robot arms. The grippers of the robot arms do not have to be parallel or at any pre-disposed positions on the object. For multiarm control, the operator chooses the same moving and control reference frames for each of the robot arms. Consequently, each arm then moves as though it were carrying out the commanded motions by itself

Neural network modeling of nonlinear systems based on Volterra series extension of a linear model

A Volterra series approach was applied to the identification of nonlinear systems which are described by a neural network model. A procedure is outlined by which a mathematical model can be developed from experimental data obtained from the network structure. Applications of the results to the control of robotic systems are discussed

Comparison of joint space versus task force load distribution optimization for a multiarm manipulator system

It is often proposed that the redundancy in choosing a force distribution for multiple arms grasping a single object should be handled by minimizing a quadratic performance index. The performance index may be formulated in terms of joint torques or in terms of the Cartesian space force/torque applied to the body by the grippers. The former seeks to minimize power consumption while the latter minimizes body stresses. Because the cost functions are related to each other by a joint angle dependent transformation on the weight matrix, it might be argued that either method tends to reduce power consumption, but clearly the joint space minimization is optimal. A comparison of these two options is presented with consideration given to computational cost and power consumption. Simulation results using a two arm robot system are presented to show the savings realized by employing the joint space optimization. These savings are offset by additional complexity, computation time and in some cases processor power consumption

Assessing NAFTA - Part III: NAFTA and the Environment

These three Working Papers look at NAFTA after four years. In Part I, the authors examine NAFTA\u27s impact on trade and investment in North America; in Part II, its impact on jobs and employment; and in Part III, its impact on environmental issues. They conclude that NAFTA is an important agreement that, together with the Uruguay Round accord, will influence patterns of trade and investment in the future. To date, NAFTA has had only a modest direct impact on patterns of trade, investment, jobs, and income. NAFTA side agreements have led to changes in environmental protection policy and in the protection and enforcement of labor rights. However, these results are also modest, and it is too early to determine any longer-term impact. The conclusion of these papers is that NAFTA was not the beginning of economic integration in North America, but rather was a response to powerful forces of change that began in the mid-1980s

Electromagnetic Monitoring and Control of a Plurality of Nanosatellites

A method for monitoring position of and controlling a second nanosatellite (NS) relative to a position of a first NS. Each of the first and second NSs has a rectangular or cubical configuration of independently activatable, current-carrying solenoids, each solenoid having an independent magnetic dipole moment vector, .mu.1 and .mu.2. A vector force F and a vector torque are expressed as linear or bilinear combinations of the first set and second set of magnetic moments, and a distance vector extending between the first and second NSs is estimated. Control equations are applied to estimate vectors, .mu.1 and .mu.2, required to move the NSs toward a desired NS configuration. This extends to control of N nanosatellites

Long-term oncological outcomes of a phase II trial of neoadjuvant chemohormonal therapy followed by radical prostatectomy for patients with clinically localised, high-risk prostate cancer.

OBJECTIVE: To determine long-term oncological outcomes of radical prostatectomy (RP) after neoadjuvant chemohormonal therapy (CHT) for clinically localised, high-risk prostate cancer. PATIENTS AND METHODS: In this phase II multicentre trial of patients with high-risk prostate cancer (PSA level \u3e20 ng/mL, Gleason ≥8, or clinical stage ≥T3), androgen-deprivation therapy (goserelin acetate depot) and paclitaxel, carboplatin and estramustine were administered before RP. We report the long-term oncological outcomes of these patients and compared them to a contemporary cohort who met oncological inclusion criteria but received RP only. RESULTS: In all, 34 patients were enrolled and followed for a median of 13.1 years. Within 10 years most patients had biochemical recurrence (BCR-free probability 22%; 95% confidence interval [CI] 10-37%). However, the probability of disease-specific survival at 10 years was 84% (95% CI 66-93%) and overall survival was 78% (95% CI 60-89%). The CHT group had higher-risk features than the comparison group (123 patients), with an almost doubled risk of calculated preoperative 5-year BCR (69% vs 36%, P \u3c 0.01). After adjusting for these imbalances the CHT group had trends toward improvement in BCR (hazard ratio [HR] 0.76, 95% CI 0.43-1.34; P = 0.3) and metastasis-free survival (HR 0.55, 95% CI 0.24-1.29; P = 0.2) although these were not statistically significant. CONCLUSIONS: Neoadjuvant CHT followed by RP was associated with lower rates of BCR and metastasis compared with the RP-only group; however, these results were not statistically significant. Because this treatment strategy has known harms and unproven benefit, this strategy should only be instituted in the setting of a clinical trial

Developing And Evaluating A Machine‐Scorable, Constrained Constructed‐Response Item

The use of constructed response items in large scale standardized testing has been hampered by the costs and difficulties associated with obtaining reliable scores. The advent of expert systems may signal the eventual removal of this impediment. This study investigated the accuracy with which expert systems could score a new, non‐multiple choice item type. The item type presents a faulty solution to a computer programming problem and asks the student to correct the solution. This item type was administered to a sample of high school seniors enrolled in an Advanced Placement course in Computer Science who also took the Advanced Placement Computer Science (APCS) Test. Results indicated that the expert systems were able to produce scores for between 82% and 97% of the solutions encountered and to display high agreement with a human reader on which solutions were and were not correct. Diagnoses of the specific errors produced by students were less accurate. Correlations with scores on the objective and free‐response sections of the APCS examination were moderate. Implications for additional research and for testing practice are offered.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/108589/1/ets200144.pd

Automation and robotics considerations for a lunar base

An envisioned lunar outpost shares with other NASA missions many of the same criteria that have prompted the development of intelligent automation techniques with NASA. Because of increased radiation hazards, crew surface activities will probably be even more restricted than current extravehicular activity in low Earth orbit. Crew availability for routine and repetitive tasks will be at least as limited as that envisioned for the space station, particularly in the early phases of lunar development. Certain tasks are better suited to the untiring watchfulness of computers, such as the monitoring and diagnosis of multiple complex systems, and the perception and analysis of slowly developing faults in such systems. In addition, mounting costs and constrained budgets require that human resource requirements for ground control be minimized. This paper provides a glimpse of certain lunar base tasks as seen through the lens of automation and robotic (A&R) considerations. This can allow a more efficient focusing of research and development not only in A&R, but also in those technologies that will depend on A&R in the lunar environment