Power Consumption and Conservation of Industrial Robots Through Embedded System

INTRODUCTION:
				1) Shutdown of Unused Components: Electric
Robot was coined by Czech playwright Karl Capek in				components consume static power in idle states.
his play R.U.R (Rossum's Universal Robots), which				Shutting down the power supply when a component is
opened in Prague in 1921. Robot is the Czech word for				idle can save the static power. When the robot stops,
forced labor.				the sensors may be turned off. If half of the time the
The term robotics was introduced by writer Isaac				sensors can be shut down, the average sensing
Asimov. In his science fiction book I, Robot, published in				power can be reduced.
1950, he presented three laws of robotics:
1. A robot may not injure a human being, or, through				2) Sensing Frequency Scaling: It is intuitive that the
inaction, allow a human being to come to harm				sensing frequency should be different when robots
2. A robot must obey the orders given it by human				move at different speeds. The sensing frequency
beings except where such orders would conflict with				needs to be higher when the speed is higher. Instead
the First Law.				of keeping the sensing frequency that satisfies the
3. A robot must protect its own existence as long as				highest speed’s need, we can reduce the sensing
such protection does not conflict with the First or				frequency when the robot moves slowly. If the robot
Second Law				moves slowly and the sensing frequency can be
				reduced.

				3) Dynamic Voltage Scaling: DVS is very effective in
INDUSTRIAL ROBOTS:				reducing processors’ power. The processor inside
				the Hitachi-8s microcontroller can work at two
Robots usually have multiple components, such as				different frequencies: 20MHz and 10MHz. The current
motors, sensors, microcontrollers and embedded				operating system inside the microcontroller doesn’t
computers. DC motors transform direct current into				support the frequency scaling. Therefore, we can not
mechanical energy and are often used to drive the				measure the power savings. However, if we can
robots. Sensors collect data from environment and				dynamically change the working frequency according
provide information to robots. Most often used sensors				to the workload, we can reduce the control power.
are vision, infrared, sonar and laser rangers. Many				This technique also applies to the embedded computer.
robots use embedded computers for high-level
computation and microcontrollers for low-level controls.				4) Trade-off between Motion and Communication:
				A Team of robots may move and cooperatively
				execute a task. Robots need to send sensing data
				through wireless communication. Consider one robot
				needs to transfer data to another robot, but the robot
				is far away. If the robots can move closer, the
				communication power can be saved. The cost here is
EPSON INDUSTRIAL ROBOT				the motion power for moving closer. If the volume of
				the data is large enough, more communication power
				can be saved than the motion power cost.

				5) Energy-Efficient Real-Time Scheduling for Robots:
				A mobile robot is a real-time system. The robot can
				have many periodic tasks, such as motor and sensor
The microcontroller directly controls motors, sensors,				control, sensing data reading, motion planning, and data
and polls the sensor readings. It hides the hardware				processing. The robot may also have some aperiodic
details from the embedded computer, and provides an				tasks, such as obstacle avoidance and communication.
application programming interface (API) for the				RTS can work with DPM to more effectively reduce
embedded computer. The embedded computer				the power consumption. For example, if a scheduler
handles high-level computation, including motion planning,				can cluster tasks closer in time and create longer idle
image processing, and scheduling. The separation of				periods, shutdown techniques can be more effective.
the microcontroller and embedded computer makes				RTS also can work with DVS to reduce processor
the designs more flexible. However, other components				energy consumption, as we discussed in the related
like sensing, control, communication and computation				work. For mobile robots, the tasks’ deadlines are
also consume significant amounts of power. It is				different at different traveling speeds. At a higher
important to consider all components to achieve better				speed, the periodic tasks have shorter periods.
energy efficiency. This study has two major				Therefore, we should consider both motion planning
contributions. Firstly, we study power consumption of a				and RTS together.
robot
				FORTIFICATION:
USES OF INDUSTRIAL ROBOTS:
One of the most common uses				Many fails to consider the third quadrant called
for industrial robots is welding. Robot welded car				fortification. This paper put some idea about that
bodies for example enhances safety, a robot never				quadrant. Some shrinks the use of robots by Fleet
miss a welding spot and performs equally all through				Size Problem [3]: A fundamental question for
the day.				multi-robot applications is to decide the number of
In assembling of parts many of these robots can be				robots needed (i.e., the “fleet-size problem”) to
found in the automotive and electronics industries				accomplish tasks. We provide a probabilistic method to
Packaging/palletizing, is still a minor application area for				decide the fleet size necessary to serve requests with
industrial robots, this application area is expected to				random arrival times and locations. We consider five
grow as robots become easier to handle.				factors on which the fleet size depends: available
The food industry is an area where robots are				energy, power consumption, service field, request rate,
expected to play a major role in the future. The				and timing constraints.
process involves harvesting each arriving plant, cutting
its steam into segments near each node, and then				Though we know that many of the industrial robots
replanting the segments so that they can grow into				uses stepper motors, servo motors, relays etc., on AC
new plants etc.				or DC. In AC supply it is must to keep the power
				factor under control it should not be low. If it so, heavy
MICROCONTROLLER AND EMBEDDED				power loss will be occurred and the company will be
COMPUTER				liable to meet the surcharge of their electricity
				department.. The following are the some of the
The microcontroller periodically sends commands to				fortification technique
motors and sensors, polls sensors’ readings, and
communicates with the embedded computer. The				1. To improve the power factor capacitor has to be
microcontroller’s tasks are usually fixed so the				used. Though robot uses electrical motors,
power consumption of the microcontroller can be				transformers etc., under starting state it needs high
modeled by a constant. The embedded computer is				capacitance to maintain pf; on the other hand under
more complex than the microcontroller. Many studies				running condition it needs minimum capacitance value. In
have been devoted into simulation-based methods to				other words it can be explained as the capacitance
estimate its power consumption [6] [5] [8]. The power				value changes according to the load of the robots.
consumption of the embedded computer may vary				These will be an extra burden to cutoff the capacitor
significantly across different programs.				under load. To overcome this dynamic control
				capacitor may be used.
				2. The one of the factor that decides the life of the
				robot is wear and tear of the electrical equipments.
				This falls in sparking of the relays contacts and motor
				brushes due to the in rush current. These can be
Micro controller				eliminated by close circuit transient.

				3. Due to energy conservation law, energy will be
				dissipated through heat. This can be reduced by silver
				windings. Silver has the lower resistance of current
				then copper and aluminum. Due to lower resistance
				of electric current it reduces major electrical losses
Motor
				4. Over load detector for example, robot with
Sensor				hardware platform of a Pioneer 2-DX robot [2]
Embedded computer				augmented with custom hardware for watering. To
				deliver water to the plant, the robot has been fitted
				with a water line, dispensing spout, and pump. To
				deliver power to wireless sensors an inductive
				charging coil has been positioned near the watering
PREVIOUS WORK:				spout. Similarly, another paddle shaped inductive charge
				coil has been added to the robot to allow it to
[1] Both timing and energy constraints are considered;				recharge itself at its “maintenance bay”. In order
the robots carry limited energy and need to finish the				to support calibration, the robot includes a sensor node
tasks before deadlines				that was human-calibrated lastly, the robot has a
				maintenance bay it uses to automatically charge its
				own batteries and refill its water reservoir. The reliability
ENERGY-CONSERVATION TECHNIQUES:				of this approach has been demonstrated during the
				deployment of the robots Rhino and Minerva as
This section explains three promising techniques for				autonomous museum tour guide robots [4, 7]. The
power reduction of mobile robots.				high-level task ordering and dispatching software was
				custom-built for the Plant Care project.
A. Dynamic Power Management
Dynamic power management (DPM) dynamically				There may be the chance to water to direct contact
adjusts power states of components adaptive to the				with the power pack. This leads to short circuit, and
task’s need. The purpose is to reduce the power				draws more current that the rated (PU) per unit.
consumption without compromising system
performance. Many electronic components have				FUTURE ENHANCEMENTS:
multiple power states; their power consumption is
different at different power states. For example,				For future work, I plan to extend the current study in
processors can run on different frequencies. To save				two directions. First, we will measure power
power, the processors can enter lower frequencies				consumption of more components, such as laser
when the workloads are light. Another example is to				rangers, cameras, servo motors, stepper motors, and
shut off the power supply to the disk in an embedded				relays. Second, I plan to implement the proposed
computer to save the static power when there is no				energy conservation techniques into the Pioneer
disk access.				robots, and conduct experiments in real applications
A simple DPM method shuts down a component
when it is idle. It is essentially a prediction problem. If we				CONCLUSION:
predict there is no access on this component for a
reasonably long period of time, the component can be				In this study, I presented some of the power
shut down to save static power. Turning on and off				consumption technique of different components of an
the component takes time and energy. If the idle period				industrial robot. In this paper, I introduce one technique
is too short, the components may actually consume				called fortification technique than two exiting techniques
more energy for turning on and off. One of the widely				DPM and RTS for energy-efficient designs of robots.
used prediction methods is timeout: if the component				These techniques together with motion planning
has been idle for a time period longer than the timeout,				provide greater opportunities for reducing the power
the component will be shut down. The rationale behind				consumption and prolonging the operation time of
timeout is that the component is likely to keep idle in				mobile robots.
the near future since it has been idle for a while.
Another widely used DPM technique is dynamic				REFERENCE:
voltage scaling (DVS) by reducing both supply voltage				[1] Yongguo Mei, Student Member, IEEE, Yung-Hsiang
and clock frequency to reduce the power				Lu, Member, IEEE, Y. Charlie Hu, Member, IEEE, and C.
consumption of processors. CMOS circuit is its				S. George Lee, Member, IEEE
dynamic power, which can be expressed by c Vdd, f,
where c is the effective switched capacitance, vdd is				[2].ActivMedia Robotics, visited Feb. 2002.
the supply voltage and f is the clock frequency.
B. Real-Time Scheduling				[3] Y. Mei, Y.-H. Lu, C. S. G. Lee, and Y. C. Hu.
Real-time systems handle tasks with deadlines.				Determining the Fleet Size of Mobile Robots with
Real-time scheduling (RTS) schedules multiple tasks				Energy Cons traints. In IEEE /RSJ International
and meet the deadlines. If the tasks can be scheduled				Conference on Intelligent Robots and Systems, pages
without missing the deadlines, we say they are				1420–1425, 2004.
schedulable. Mobile robots are real-time systems.
When a robot detects an obstacle, it has to timely				[4]. Burgard, W., A. Cremers, D. Fox, D. Haehnel, G.
slow down and decides the next motion. For multiple				Lakemeyer, D. Schulz, W. Steiner and S. Thrun. 1999.
robots coordinating to accomplish a task, timely				Experiences with an interactive museum tour-guide
information communicating is critical. Two often used				robot. Artificial Intelligence.
scheduling algorithms are rate monotonic (RM) and
earliest deadline first (EDF). Many other algorithms are				[5] J. R. Lorch and A. J. Smith. Apple Macintosh’s
based on these two. RM is a fixed-priority algorithm,				Energy Consumption. IEEE Micro, 18(6):54–63,
assigning a higher priority to a task with a shorter				November 1998
period. EDF executes the task with the earliest
deadline among all ready tasks. It has been proved				[6] D. Brooks, V. Tiwari, and M. Martonosi. Wattch: A
that EDF is optimal with respect to minimizing the				Framework for Architectural-level Power Analysis and
maximum lateness. Besides scheduling tasks to meet				Optimizations. In International Symposium on Computer
their deadlines, RTS can also schedule the tasks such				Architecture, pages 83– 94, 2000.
that DPM can save more energy. For example, when
the idle periods of a component are too short due to				[7]. S. Thrun, M. Bennewitz, W. Burgard, A. Cremers, F.
frequent accesses, power cannot be saved by				Dellaert, D. Fox, D. Haehnel, C. Rosenberg, N. Roy, J.
shutting down the component. However, if we can				Schulte and D. Schulz. 1999. MINERVA: A second
reschedule the tasks and make the component have				generation mobile tour-guide robot. In Proceedings of
more long idle periods, the component may be shut				the IEEE International Conference on Robotics and
down to save power.				Automation (ICRA).
C. Examples
In this section, we show some potential applications of				[8] T. Simunic, L. Benini, and G. D. Micheli.
DPM and RTS into energy-efficient robot designs using				Cycle-accurate Simulation of Energy Consumption in
several examples.				Embedded Systems.

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Power Consumption and Conservation of Industrial Robots Through Embedded System