The contributions to this issue aim to provide robotics and, in general, the automatic control community with results of research and applications focused on the cost-effectiveness of automation systems.

Low Cost Automation or Cost Effective Automation promotes cost oriented reference architectures and development approaches that properly integrate human skill and technical solutions, includes decentralized process control strategies, addresses automation integrated with information processing, as well as automation of non-sophisticated and easily handled operations for production maintenance.

Low Cost Automation is not an oxymoron like military intelligence or jumbo shrimps. It opposes the rising cost of sophisticated automation and propagates the use of innovative and intelligent solutions at an affordable cost. The concept can be regarded as a collection of methodologies aiming at exploiting tolerance of imprecision or uncertainties to achieve tractability, robustness and, in the end, low cost solutions. Mathematically, elegant designs of automation systems are often not feasible because of neglecting real world problems, i.e. they are failure-prone and therefore often very expensive for their users.

Low Cost Automation does not mean basic or poor performance control. The design of automation systems considers their life cycle with respect to their costs. For example, machine vision, despite in some cases costly components, properly applied can reduce the overall cost. It is used to guide field robots, identifying and assembling parts, and to sort out agricultural products.

Whenever a mobile robot has to deal with an environment that is totally or partially unknown or dynamically changing, local navigation strategies are very important for the robot to successfully achieve its goals. Unfortunately, local navigation algorithms that have been proposed in the literature offer poor performance (or even fail) whenever the geometry of the free space in which the robot is requested to operate increases its complexity. In this paper, we deal with a team composed of many robots, and we show how robots navigating within an unknown environment with local communication capabilities (only line-of-sight communication is allowed) can cooperate by helping each other to achieve their own goals.

Biological Robotics covers the interface between robotics and behavioural biology. The first international conference in this area took place in Paris in 1990. This meeting led to the development of what is now called the Society for Adaptive Behaviour (SAB), which holds an international meeting every two years.

Stroke is a common condition resulting in 30,000 people per annum left with significant disability. In patients with severe arm paresis after stroke, functional recovery in the affected arm is poor. Inadequate intensity of treatment is cited as one factor accounting for the lack of arm recovery found in some studies. Given that physical therapy resource is limited, strategies to enhance the physiotherapists' efforts are needed. One approach is to use robotic techniques to augment movement therapy.

A three degree-of-freedom pneumatic robot has been developed to apply physiotherapy to the upper limb. The robot has been designed with a workspace encompassing the reach-retrieve range of the average male. Control experiments have applied force and then position only controllers to the pneumatic robot. These controllers are combined to form a position-based impedance control strategy on all degrees of freedom of the robot. The impedance controller performance was found to be dependent upon the specified impedance parameters. Initial experiments attaching the device to human subjects have indicated great potential for the device.

ADVANCED NEURO-ROBOTICS

1. ‘Robo Rat' project

United States scientists from SUNY Downstate Medical Centre have reported on a Robo Rat project that they have initiated. In a research paper published in Nature (May, 2002) they describe some of their remarkable results. It may soon be possible, we are told, that because of their researches, a remote-controlled living ‘Robo Rat' could be involved in numerous and varied applications. Their work is a spin-off from research to give paralysed people the ability to move and feel artificial limbs. The report of the project presents their findings and described how five rats carrying a special backpack, which contained a battery, radio receiver and brain stimulator, were controlled by a human operator sitting up to 500 yards away. The human operator was able to make them weave in and out of obstacles and navigated them over a course. Instead of using the traditional methods ofanimal training which associated behaviour with rewards, the researchers directly stimulated the parts of the animals' brains that responded to the movements of their whiskers and to receiving rewards of food. Electrical signals were sent to parts of the brain and provided a virtual contact to the animal's whiskers, showing them which way the operator wished them to go. In their research paper it is shown how by stimulaling these ‘whisker centres' the rats could be steered and by stimulating the brain's reward centre, they could reinforce the correct behaviour.

The four papers encompassing this special section on Robot Mediated Neuro-motor Therapy introduce a new area for robotics in the healthcare industry, that of assisting in the delivery of neuro-motor therapies, for patients recovering from a stroke. As life expectancy increases, so do problems associated with old age. In the paper by Krebs et al. the authors not only summarise the need for action in stroke rehabilitation but also makes a useful distinction between assistive technologies that provide enhanced abilities for the patient, and therapy tools for the clinician, that seek to enhance the patients recovery.

This paper considers human-centered and socially appropriate robots as well as automation systems within the context of their cost-effectiveness. Usually, the objection of system designers is that approaches for human-centered and socio-technical design result in systems that are more expensive than those made by traditional methods, and are therefore not truly affordable, in particular for small and medium sized enterprises (SMEs). This widespread opinion is challenged in the paper by some arguments supporting the forecast that human-centered and socio-technical design will soon become justifiable in tangible (economic) as well as intangible benefits for all involved partners, including society at large.

In this paper, methods based on various spline techniques for planning and fast modifications of a trajectory for robot manipulators are investigated. Algebraic and trigonometric splines, their combined use, and the use of the B-spline technique are analyzed and compared in detail. In so doing, we focus on the performance of sudden changes in a predefined trajectory, e.g. obstacle avoidance in real-time applications. Some comparative examples illustrate our results.

Thie first biologically inspired robots, the famous electromechanical tortoises, were designed and built in 1949 by W. Grey Walter. This paper reviews their origins in Walter's theories of the brain and the nature of life, and uses contemporary unpublished notes and photographs to assess their significance then and now.

The passivity property of a noncollocated single-link flexible manipulator with a parameterized output is studied. The system can be characterized by either the irrational transfer function of an infinite-dimensional model or its truncated rational transfer functions. Necessary and sufficient conditions for these transfer functions to be passive are found. It is also shown that a non-passive, marginal minimum-phase, truncated transfer function can be rendered passive by using either the root strain feedback or the joint angular acceleration feedback. For the noncollocated truncated passive transfer function, a PD controller suffices to stabilize the overall system. Numerical results are given to show the efficacy of the proposed approaches.

Today, in robot applications continuous paths often result from CAD or other planning tools. We present here an approach to the question that has been discussed for a long time, i.e. how to approximate a given path by a second one in such a way that the latter lies in a tube of given radius ε around the first. The approximation should be a (normally cubic) spline with a small number of breakpoints. The strategy is based on algorithms used in “computer aided geometric design” and is applied to examples from industrial and surgical robotics.

Robot-aids or Rehabilitators are our chosen neologism to name a new class of robotic devices that represent a substantially departure from prior applications of robotics in rehabilitation. Rather than use robotics as an assistive technology for a disabled individual, we envision robots and computers as supporting and enhancing the productivity of clinicians in their efforts to facilitate a disabled individual's recovery. In this paper, we attempt a brief overview of our work in what promises to be a ground breaking field. We discuss the concept of robot-aided neuro-rehabilitation as a means to deliver therapy, measure patient performance, and also as a design tool. To illustrate the broad spectrum of neurological diseases that this technology might impact, we will illustrate each case with a different pathology, namely cerebral vascular accident (CVA – also known as stroke), Parkinson's disease (PD), and cerebral palsy (CP).

This paper demonstrates a new method in sampling environmental variables and underwater currents using special devices with a particular technique. The project involves developing a set of robots as the tools for data collection, and developing a system that can interpret the data collected. The ‘ocean' currents can be mapped using a flock of robots by dropping them into the ocean. As they descend, they record the desired sensory information such as salinity, temperature, pressure, the presence of specific chemicals, etc., along with other variables required for the system to function. Once at a predefined depth the robots start ascending and still continue collecting data until they reach the surface. Back on the surface, they communicate the collected data to a base computer in a ship or on land, through satellite or other means. The base computer collects the data from every recovered member of the flock and reconstructs the path they took underwater. Then using this path, it estimates the vectors of the oceanic currents. The environmental variables can be displayed in 3D for the sampled area.

This paper presents new low-cost systems for the automation of some fish farm operations. Particularly, computer vision is applied to non-contact fish weight estimation. Stereo vision systems with synchronised convergent cameras are employed to perform fish 3-D segmentation in tanks and sea cages. Several pre-processing algorithms are applied to compensate for illumination local variations. The approach applied for fish 3-D segmentation consists in detecting in both images certain fish features. Once these points have been detected and validated in both images, the fish are 3-D segmented by applying stereo vision matching considerations. Fish weight is estimated by using simple length-weight relations well known in the aquaculture domain. The paper also briefly describes robotics systems for fish feeding and underwater pond cleaning, which can be also used to implement the above mentioned computer vision techniques for the fish estimation.

Lie algebra is an area of mathematics that is largely used by electrical engineer students, mainly at post-graduation level in the control area. The purpose of this paper is to illustrate the use of Lie algebra to control nonlinear systems, essentially in the framework of mobile robot control. The study of path following control of a mobile robot using an input-output feedback linearization controller is performed. The effectiveness of the nonlinear controller is illustrated with simulation examples.

Due to the increasing popularity of surveillance and security systems, the problem of automatically tracking a moving target by visual servoing has become a research topic deserving more investigation. Nonetheless, the success of tracking a moving target in real-time primarily depends on the performance of the motion detection techniques employed. This paper addresses visual tracking control of an unknown target that could be motional arbitrarily in the scene. A pan-tilt mechanism is used to gain the flexibility of tracking, and the so-called region-based matching method and motion energy method are modified and proposed in this study to detect a moving target based on the consecutive images acquired. A visual servo control scheme that adopts proportional control in the visual loop for reducing the servo lagging is proposed using output disturbance feedforward compensation. Experimental results show the superiority of the proposed method in achieving high system bandwidth and tracking accuracy.

Hemiplegia, affecting approximately 75% of all stroke survivors, is a common neurological impairment that results in upper and lower limb sensory and motor deficits. Recovery of coordinated movement of both upper limbs is important for bilateral function and promotes personal independence. This paper describes the philosophy and design of Driver's Simulation Environment for Arm Therapy, a one-degree-of-freedom robotic device that uses a modified Constraint-Induced therapy paradigm to promote coordinated bilateral movement in the upper limbs. Baseline force and tracking data for four neurologically unimpaired subjects who completed bilateral and unilateral steering with the impaired arm using the device are presented.

The minimum-time path-following problem for non-redundant manipulator has already been analyzed and a number of efficient solution algorithms have been proposed. These algorithms can be applied also to redundant manipulators if the path is assigned in the joint space. If the path is assigned in the task space instead, how to exploit kinematic redundancy to reduce the execution time is still an open problem. In this paper it is proposed to follow a heuristic approach to choose between different solutions to the inverse kinematics problem that underlies the minimum-time path-following control problem. The aim is to obtain a joint-space path which configures the manipulator so as to improve acceleration/deceleration capabilities of the end-effector. This is obtained by penalizing the motion of joints with higher inertia-to-torque ratios. Numerical results are presented for an “easy-to-understand” three degree-of-freedom planar manipulator involved in two-dimensional paths.

In this paper we describe a prototype underwater robot capable of altering its density by heating oil. It is designed to gather information in the ocean, as a member of a flock of such robots. We also describe the forces acting on the robot, and suggest a preliminary control model.

We are developing robotic devices for locomotion training after spinal cord injury. In this paper, we compare two approaches to controlling and quantifying bipedal stepping of spinal rats with robots. In the first approach, the rats stepped on a physical treadmill with robot arms attached to their lower shanks. In the second, the rats stepped on a virtual treadmill generated by the robots. The rats could step on the virtual treadmill, but stepping was more consistent, step height greater, and interlimb coordination improved on the physical treadmill. Implications for the role of sensory input in the control of locomotion and the design robotic of step trainers are discussed.