Various stair-climbing or cleaning mechanisms have been proposed or developed in the past decades. Most of them are big-sized, complex, and/or expensive, which hinder their practical application. In this study, a new stair-cleaning robot is proposed and developed. In the new robot, a pair of legs is used for stair climbing. Rotating around the main body, the legs of the robot drive the feet to execute revolving but translational motions, thereby allowing the robot to climb. The new robot is highly compact compared with most traditional stair-cleaning or climbing robots, because only one motor is utilized to drive the climbing mechanism and the legs can be retracted at both sides of the robot when it is not climbing. Its compact structure enables the new robot to move along the riser to do cleaning on the stairs, which is a prominent advantage over most similar robots. The cleaning device is designed similar to that of current ground cleaning robots. The sensing and control system is designed for successful stair climbing and avoidance of falls and collisions. Experiments show that the new robot has high success rates in climbing up or down common types of stairs, and thus can do cleaning on the related stairs.

Purpose: This paper aims to investigate the perception threshold (PT) of electrotactile stimulation under non-steady contact condition (NSCC) which is rarely considered in previous reports mainly because of the difficulty with experimental control. Three factors of NSCC are involved, including the current alternating frequency, the tapping interval of stimulation and the stimulating area of skin. The study is aimed at providing the basic PT data for design and application of wearable and portable electrotactile device. Design/methodology/approach: The up-down method was selected to assess PT, and 72 experimental scenarios were constructed. During the study, we developed an experimental platform with the function of data record and programmable current stimulation. With psychophysical experiment, more than 10,000 data were collected. Furthermore, statics analysis and ANOVA test were opted for exploring the main factor influencing PT. Findings: NSCC has different PTs on each body location, and PT has a positive correlation with frequency. In general, PT in NSCC is significantly lower than that in SCC. In some cases, it can be lower by more than 60 per cent. In addition, women have a lower PT than men across all age groups, and the younger is generally more sensitive than the older in electro-sensation. Research limitations/implications: Limited factors of NSCC were considered in this study. Contact time and break interval should be investigated in the future work. Practical implications: The paper includes implications for the development of smart electrotactile device. Originality/value: This paper fulfills a challenge in assessing the PT under NSCC.

Housler based magnetic controlled shape memory alloys are characterized by a large magnetic field induced strain. The strain was dependent on the twin martensite structure rearrangement, and the rapid solidification technology had a significant influence on the microstructure, physical, and chemical properties of the alloy. Thus, the structure and the martensitic transformation changes of Co₃₃Ni₃₁Al₂₇Fe₉ during the rapidly solidified process were studied. The microstructure of Co₃₃Ni₃₁Al₂₇Fe₉ with furnace cooled and rapid solidification (RS) constitutes a dual-phase structure, β phase and γ phase in a low cooling rate and martensite and γ phase in a high cooling rate. The γ phase at the grain boundaries reduced and became more fragile by raising the R_C value. The one-step austenite-martensite phase transformation occurred during the process of heating and cooling. The phase transition temperature presents an increasing trend by rising the cooling rate, even to over the room temperature. Moreover, the martensite structure in Co₃₃Ni₃₁Al₂₇Fe₉ constitutes a typical L1₀-type twinning structure.

In the industrial applications of ferromagnetic shape memory alloy, the large magnetic field induced strain and long function fatigue life are the essential conditions for their application. In this cases, the ferromagnetic shape memory effect and the function fatigue of Ni₂MnGa under applied magnetic field has been investigated. The magnetic field induced strain appear typical nonlinearity increasing trend apparently with the applied magnetic field rising. Meanwhile, the magnetic field induced strain keep decreasing tendency as the applied magnetic field cycles increasing and the magnetic field induced strain kept a small value in a long cycle ranges of 400 to 10⁷. Furthermore, the sample appeared typical elastic deformation stage, twin martensite remigration stage and plastic deformation stage during compression test process.