PurposeThe purpose of this paper is to review the current application areas of shape memory alloy (SMA) actuators in intelligent robotic systems and devices.Design/methodology/approachThis paper analyses how actuation and sensing functions of the SMA actuator have been exploited and incorporated in micro and macro robotic devices, developed for medical and non‐medical applications. The speed of response of SMA actuator mostly depends upon its shape and size, addition and removal of heat and the bias force applied. All these factors have impact on the overall size of the robotic device and the degree of freedom (dof) obtained and hence, a comprehensive survey is made highlighting these aspects. Also described are the mechatronic aspects like the software and hardware used in an industrial environment for the control of such nonlinear actuator and the type of sensory feedback devices incorporated for obtaining better control, positioning accuracy and fast response.FindingsSMA actuators find wide applications in various facets of robotic equipments. Selecting a suitable shape, fast heating and cooling method and better intelligent control technique with or without feedback devices could optimize its performance.Research limitations/implicationsThe frequency of SMA actuation purely depends on the rate of heat energy added to and removed from the actuator, which in turn depends upon interrelated nonlinear parameters.Practical implicationsFor increasing the dof of robots, number of actuators also have to be increased that leads to complex control problems.Originality/valueExplains the suitability of SMA as actuators in smart robotic systems, possibility of miniaturisation. It also highlights the difficulties faced by the SMA research community.

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Surface topography and, in particular, roughness and form, plays an important role in determining the functional performance of engineering parts. The measurement and understanding of surface topography is rapidly attracting the attention of the physicist, the biologist and the chemist as well as the engineer. Optics in general played an important role in measurement and, with the advent of opto-mechatronics, it is once again at the forefront of measurement. In this paper, the principles and performance of a confocal microscope, together with the measurement system, are described. Suitable fixtures are developed and integrated with the computer system for generating three-dimensional surface and form data. Software for data acquisition, analysis of various parameters including new parameters and visualization of surface geometrical features has been developed. Both the intensity and the auto-focus methods are used to measure two-dimensional surface roughness by use of the system and results are presented. The measurement and characterization of three-dimensional surface topography and form error will be presented in part II of this paper.

A conventional two-stage servo valve basically consists of an electrically operated torque motor as the first stage and spool valve as the second stage. Owing to the limitation in the band width, servo valves are not suitable for high-frequency applications. The work presented in this paper deals with the methodology of the mechatronics approach for the design of a piezoelectric actuator with a mechanical amplifier and its integration into a servo valve. The analysis and simulation of a multilayer piezoelectric actuator (MLA) a with mechanical amplifier for high-frequency application has been done using icon-based bond graph technique and finite element coupled field analysis for the commercially available piezoelectric actuator. The designed piezoelectric actuator was integrated into an existing flapper-nozzle servo valve by replacing the first stage. The dynamics of the valve integrated into a piezoelectric actuator has been simulated. The required simulation parameters for the actuator have been derived from a finite element model. An experimental set-up has been designed and the integrated testing of the servo valve with piezoelectric actuator has been carried out to determine the no-load flow gain of the valve. Also the time response has been measured for a conventional servo valve and servo valve with piezoelectric actuator. The designed valve with a piezoelectric actuator has satisfactory static and dynamic characteristics for high-speed applications.

This paper reviews recent developments in nonlinear control technologies for shape memory alloy (SMA) actuators in robotics and their related applications. SMA possesses large hysteresis, low bandwidth, slow response, and non-linear behavior, which make them difficult to control. The fast response of the SMA actuator mostly depends upon, (1) type of controller, (2) rate of addition and removal of heat, and (3) shape or form of the actuator. Though linear controllers are more desirable than nonlinear ones, the review of literature shows that the results obtained using nonlinear controllers were far better than the former one.\ud Therefore, more emphasis is made on the nonlinear control technologies taking into account the intelligent controllers. Various forms of SMA actuator along with different heating and cooling methods are presented in this review, followed by the nonlinear control methods and the control problems encountered by the researchers

Large displacement static analysis of a fully compliant spatial mechanism is presented here. This mechanism is made up of a superelastic nitinol pipe as its compliant structural member and actuated by three shape memory alloy (SMA) wires. The coupled effect of the force developed by the SMA actuation and the force required for elastica deflection is simplified by incorporating the geometric parameters of the mechanism using a deflection plane approach. An iterative algorithm with elliptical integration has been developed, which is suitable for a wider range of actual and arbitrary inputs. The solutions are obtained for the effect of one-wire and two-wire actuation methods. Results obtained from the deflection plane approach and simulation have been compared and found that the relative error is less than 1% within the safe operating range of 5% strain value recommended for SMA actuators. Based on the analytical and simulation inputs, the mechanism is miniaturized further with the aim of increasing its workspace and is fabricated for further experimental investigations.