Analytical Modelling and Design of a Mechatronic Cradle System

IJSRD - International Journal for Scientific Research & Development| Vol. 3, Issue 10, 2015 | ISSN (online): 2321-0613

Analytical Modelling and Design of a Mechatronic Cradle System R. Dinesh1 V. Murugabalaji2 P. N. Sundarajan3 1,2,3 Assistant Professor 1,2,3 Department of Mechanical Engineering 1,2,3 SVS College of Engineering, Coimbatore, India Abstract— Cradle is an appliance which use to carry a baby and oscillate automatically with certain speed for comfort sleep of a baby. Babies sleeps sound in mosses baskets or cradle, as they afford a limited sleeping atmosphere which helps them feel secure. It's important to ensure that swinging cradle are locked when not in use or when baby is unattended, particularly as baby gets older and stronger.Most appropriate time to maneuver baby from a mosses basket or cradle to a cot is between four to six months, or until your baby starts to push up onto their hands and knees and sits unaided. There is a need to develop a advanced automated oscillated baby cradle because the existing cradles are imported and costly.

This design and implementation of a new automated oscillating cradle that swings automatically and sends text messages continuously to the linked mobile numbers when baby cries with the assistance of mechatronics system is developed.

Key words: Cradle, Angle of oscillation, C-channel, Global System for Mobile communication (GSM)

Sulphur

0.040% max

Phosporous 0.040% max Table 1: Composition of mild steel The design and implementation of a new automated oscillating cradle focuses to swings automatically when baby cries. DC motor is used to oscillate the cradle. The speed of the cradle can be controlled by the belt system. The C-channel uses to converts the circular motion into linear motion. It has a sound sensor system which detects the baby cry sound and accordingly the cradle swings. This system helps parents and nurses to take care of babies without physical attention. The Fig.1 shows the existing cradle system. It consists of frame, huck, stand and cradle. It is made of different materials like cast iron, steel, alloy and plastic etc. Another type of cradle has the rollers to move if from one place to other. These types of cradle are mostly used in hospitals. It is oscillated by minimizing the human effort to the greater extent.

I. INTRODUCTION Cradle is an invention which is used to carry a baby and which moves from side to side proving oscillating motion. It is a frame to keep the bedclothes from contact with the body feeling secure and comfort. The rocking or gliding reaction of a crib should help baby settle. To enhance an undisturbed sleep and amenity, automated oscillating cradle is developed.

The microcontroller that has been used for this project is from PIC series.

PIC(Peripheral Interface Controller) microcontroller is the first RISC(Reduced Instruction Set Computer) based microcontroller composed in CMOS (Complementary Metal Oxide Semiconductor) which incorporate isolated bus for guidance and allowing the data simultaneously to ingress the program and data memory. Low power consumption is the major benefit of CMOS and RISC combination which results in reduction of chip size to a minute sized pin. The main impact of CMOS is that it has immunity to noise than other fabrication process.

Fig. 1: A Typical Cradle System III. DESIGN ANALYSIS

II. MATERIAL SELECTION Selection of belt material is based on the power of motor, P. We consider the (A) section V-belt. For that  Nominal top width= 13 mm  Nominal thickness of belt =8 mm  Weight per meter = 0.106 Kgf For the C-Channel link rod, frame and mechanism, the mild steel is chosen due to the following reason. The mild steel compositions shown in the Table1 Material Composition 0.16-0.18% Carbon 0.40% max Silicon Manganese

0.70-0.90%

Fig. 2: Design of Automated Oscillating The period of motion, T= 2π√(L/g) (1) Angular Length, L= √ (5002 + 2952) L= 580 mm

Cradle System

T= 2 x π√(580/9.81)

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Analytical Modelling and Design of a Mechatronic Cradle System (IJSRD/Vol. 3/Issue 10/2015/097)

T= 48.28 sec Time per oscillation, t = N/T N- Number of revolutions t= 40/48.28 t= 0.828 sec If, θ is Maximum angle of oscillation θ= tan-1(L/g)

(2)

(3)

θ= tan-1(500/295) θ= 66˚06’ The cradle is designed according to the values of time period, time per oscillation and maximum angle of oscillation as arrived from the above equations (1),(2) and (3) respectively.

IV. MECHATRONIC CIRCUIT FEATURES It Uses the extremely popular SIM300 GSM module and can be controlled by standard AT commands. It Provides the industry standard serial RS232 interface for accessible network to computers and its auxiliary devices. It afford serial TTL directly interfaced to microcontrollers.It incorporates Power, RING and Network LEDs for easy debugging. 3V Lithium Battery holder with applicable circuitry for maintaining backup that modules the internal RTC. It is based on GSM based Voice communications, Data/Fax, SMS,GPRS and TCP/IP stack. Module’s operation mode can have the control over the PWR Switch connected to the PWR pin. It comes with an onboard wire antenna for better reception and optioned for adding an external antenna along through an SMA connector. The SIM300 allows an alterable serial baud rate from 1200 to 115200bps (9600 default). It Modem a low power consumption of 0.25A during normal operations and around 1A during transmission. Operating Voltage: 7–15V AC or DC. The mechatronics arrangement used for arriving the working model of Automated Oscillating Cradle System has been shown in Fig.3 and Fig.4

Fig. 3: Mechatronics circuit

Fig. 4: Working model of Automated Oscillating Cradle System V. CONCLUSIONS The present work reduces the human effort and particularly mother’s stresses in working times.The period of oscillation of the cradle is maintained for over requirement. The cradle has a uniform controlled oscillation which creates a good atmosphere for the baby to sleep. The present work is economical and user friendly and very useful for working parents and attendants as they get alerts through their mobile phones and manage their work efficiently REFERENCES [1] Anritha Ebenezer; Anupreethi. S; “Automatic Cradle Movement for Infant Care” Undergraduate Academic Research Journal (UARJ), Vol. 1, No. 1, pp. 2278 – 11292012.

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[8] Christiaan Huygen (1665) observed that the cradle link harmonic oscillator and the system models have a single degree of freedom.

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