Robot Actuators

 An actuator is a mechanism for activating process control equipment by use of pneumatic, hydraulic, or electronic signals. There are several types of actuators in robotic arms.


Types:
A hydraulic actuator consist of a cylinder or fluid motor that uses hydraulic power to facilitate mechanical operation. The mechanical motion gives an output in terms of linear, rotary or oscillatory motion. Because liquid cannot be compressed, a hydraulic actuator can exert considerable force, but is limited in acceleration and speed.
A pneumatic actuator converts energy formed by compressed air at high pressure into either linear or rotary motion. Pneumatic energy is desirable for main engine controls because it can quickly respond in starting and stopping as the power source does not need to be stored in reserve for operation.
An electric actuator is powered by motor that converts electrical energy to mechanical torque. The electrical energy is used to actuate equipment such as multi-turn valves. It one of the cleanest and most readily available forms of actuator because it does not involve oil.
A mechanical actuator functions by converting rotary motion into linear motion to execute movement. It involves gears, rails, pulleys, chains and other devices to operate.

Examples of Rotating Actuators : 

1. DC Motor
2.DC geared motor
3.Servo motor
4.Stepper Motor
5.BLDC motor
6. AC Servo Motors



Examples of Linear Actuators :

1. Solenoid
2. Linear Servo Motors
3.Linear Stepper Motors

You can convert linear motion into rotating motion or rotation motion into linear motion in many different ways.

Criteria for RUET ROBO RUN

Task : 
Each team has to build one autonomous bot which is able to go following the line
given in the arena.



Bot specification:
The bot must fit within 25cm * 25cm square. The power supply must be
dc(<=24V) installed in the bot. The bot must not do any harm to the arena or any
human being.



Arena Speciation:
As  specified in the figure (Black line on white background) .Run will start in the
start position and will end in end position as specified. In the path there are some
check points.



Rules for selecting winner:
Winner will be selected according to point earned. Earning the higher point will
get a higher rank. In the final round speed will be considered.
 

Fig1: Full Arena (Red mark text will not be present in original arena)

Fig2: Specification of dimensions of the arena 

Rules for points:
1.  Crossing every check point will be awarded with 3 points.
2.  Stopping at the end point will be awarded with 3 points.
3.  If the bot go outside the arena or stop or any other inconvenience occurs it
must take a restart.
4.  A team can take at most 5 restarts.
5.  A penalty of 1 point will be deducted from the score for every restart.
6.  While restarting the bot will be placed in the last check point it passed.
7.  Before restarting a team cannot do any major hardware change or any kind
of software change.


Rules for game play:
1.  One bot at a time will run in the arena.
2.  A team will have total 10 minutes to complete its run.
3.  Two rounds will be played among all team.
4.  A final round will be played between first, second and third according to
total point earned in the first two rounds.
5.  A team will be fully responsible for the safety of their bot.
6.  Judges have all the rights to take decision during the game play.

Rules for disqualification:
1.  A team will be disqualified if the bot does not fulfill the bot specification
criteria.
2.  A team will be disqualified if any attempt of cheating is made.
3. A team will be disqualified if any unfair behavior is seen.

Choice of Battery for Line Follower Robots

As normally line follower robot is small in size and need to accelerate quickly the choice of battery is very important . The size of the battery need to be small and the weight need to be very low. The power storage of the battery needs to be high.

Rechargable Battery :

 As the bot needs to run again and again choosing a rechargeable battery will be sensible. Two types of rechargeable battery can be used.

1. Lithium-ion battery
Mobile phone battery can be used. One mobile phone battery gives 3.7 v. Connecting them is series gives higher voltage and connecting them in paraller gives higher backup. The energy capacity is rated in mAh rating . Higher the mAh rating higher is the storage capacity and higher is the backup.

2.Lithium polymer battery:
Lithium-ion polymer batteries, polymer lithium ion or more commonly lithium polymer batteries (abbreviated Li-poly, Li-Pol, LiPo, LIP, PLI or LiP) are rechargeable (secondary cell) batteries. LiPo batteries are usually composed of several identical secondary cells in parallel to increase the discharge current capability, and are often available in series "packs" to increase the total available voltage.
Before using them just learn the safety precaution. They explode in high temperature. They need to be charged using controlled charger.

 



Non Rechargeable Battery :
If some one wishes to use non rechargeable battery then 9v Duracell batteries can be used.

My experience:

I used mobile phone batteries in series in my robot. They gave good backup, low weight and seize make it convenient and also good life time.