For identifying standing & sitting body posture, you may use image processing technique using LabVIEW or MATLAB programming.

You can use strain gauges at the joints and backbone attached by some means to identify the proper posture of the body. A Mechanism can be developed which monitors the present posture of body and indicate if it's wrong.

Not a field of my expertise, but if I have to give an idea I'll suggest by using blood pressure. During different body positions, different body parts of body experience different blood pressure like pressure is highest in feet while standing, lowest while lying down. So a device that has standard blood pressure values will work as a parameter for ideal posture. the device will not be that much electrical. However, other another device can be developed using small emitters which will emit harmless radiations which will give the distance of the body part where emitter is attached from a fixed reference line like ground level, waist line, etc. using SONAR principle. Few such emitters will give the overall state of body and standard values (already set in device) will give the posture perfection. This method will however will be elaborate and tedious due to absence of only one emitter.

Forgive me for any errors or childish assumptions coz this isn't my field and I am still a student.

There is a project by Qi Wang on Smart Rehabilitation Garments, on monitoring the correct body posture. The prototype named Zishi. Maybe you can take a look on that. =)

Do you have any link to that project @M.Z.Baharom?

@zulkifli here is the link that I found on the details of the Zishi project.

http://www.by-wire.net/zishi-posture-sensing-garment-for-rehabilitation/

My investigations of body posture have revealed that posture is highly variable and dependent upon person, activity and constraints in that activity.  More important is the capacity within the environment for anyone to change posture.  There are many techniques for measuring body posture but the ultimate question concerns the posture associated with the activity and can the posture change.  For example, short drivers use an erect posture to raise their eye height for driving while tall drivers use a slumped posture to fit in the car.  The question is whether drivers can sit in these postures in the same car and is there capacity within the car seating package to allow a change of posture.  We have learned that repetitive motions are dangerous and fixed, "good" postures are dangerous.  Thus, I would recommend a question concerning how to measure the range of postures available within an activity rather than one that assumes there is a "good posture" for everyone in the investigation.

Dear Prof Herbert, is it your example is related to the ergonomics concerns. It is really interesting when you asking something that we can think together and it is promising for me. Is there any method that I can used, if I just want to consider the standing position without any movement. Or in other words, balancing conditions. 

The challenge lies in recognizing and measuring the spinal curvature.  The spine transmits loads when standing depends upon the position and orientation of the pelvis and all structures above it.  For sitting, we measured each subject with anatomical landmarks that were visible by video cameras to determine the position of the chest relative to the pelvis.  In a standing posture, the environment becomes infinitely more complex because it is difficult to measure three anatomical landmarks on the pelvis from which a reference axis system can be built to determine the position and orientation of the structures above.  For example, in the simplest two body system, the torso is viewed as rigid pelvis and chest structures and "bending" structure in between (the lumbar vertebrae) however you want to model it is some form of an elastic component.  The position of the chest relative to the pelvis will give you the approximate orientation and shape of the lumbar "connectors."  All of this requires some measurements of the subject under a controlled environment to deveolop the reference planes and how they define the shape of the lumbar curve.  There is much variation in shapes of these structures that affects the accuracy of the measurements in 3d.  I think that this is enough for this form of communication and I believe that I have given you enough to pursue a plan using video measurement techniques.  I'm not sure that electronic sensors, unless they are rigidly attached to these skeletal structures will satisfy your needs.  That may be a possibility but it is extremely uncomfortable for subjects to wear instrumentation that compressing their soft tissue sufficient to remove its effects on the measurements.  You might combine a force plate system with the video measurements to estimate the positions and postural orientations from a model, but again this will require considerable measurement of each individual to establish a model with any fidelity for their condition.  Good luck and I hope this helps.

Posture is the result of a complexo sensori-motor process of integration to adapt the body to the gravitation camp.  It is an active process with the musculoskeletal system as a the final effector. When the individual stays in  bed or any alternative horizontal rest situation he gets into a different passive situation which we call "position". Posture is un unstable active situation because submitted to the pernanent action of gravity, regulated by the triple mechanism of equilibrium, visual, propiceptive and vestibular. In this sense good posture cannot be normalized: it is an individual matter in its respnse to the environment, so it cannot be defined by imaging techniques. Instead it is necessary to define good "static" posture as the one that is the most echonomic in terms of energy cost. In this sense, the best probably aproach is to record muscular activity by sEMG with electrodes placed in antigravitatory muscles of both the truck and low extremities. When studing patient suffering from low back pain we use to place bilateraly electrodes at T12 and S1 levels with the individual in relaxed standing position.  We never record nil activity, although this increases in some patients and also in some asymptomatic individuals which we consider as unable to complete relax.

stabilometry by a foot sensor connected to a PC.

good luck

There must be first more understanding, that the individual posture is the resultant of processes and activities during the compete period of growth. The most optimal human posture while standing as an adult should show a straight line between the ears, the center of the humeral head, the trochantor major and the center of the foot. If that is so, the spinal curvature will always show only a slight high thoracic kyphosis and corresponding slight cervical lordosis and a long ( including Th10-L2) lumbar lordosis. If the thoracolumbar spine does not develop its maximal function, especially its counter-clockwise rotational function ( torque and countertorque) to facilitate the evolutionary "innovation" in spinal function: the connective function of the thoracolumbar joint between the pendulum of the pelvis with the legs and a reversed pendulum of the shouldergirdle and the arms.

Sitting on chairs in the presence of the human pelvis, that cannot accomodate this position at all means a disturbing external factor to develop optimal postures. And with bad postures the shearloads in all elements of the spine will give troubles. You will not easily find a cohort of people with only good postures in the western world, where the introduction of handheld game -and electronic devices accelerated the incidence of spinal postural problems with its devastating effects on the health of spinal discs and ligaments.

Besides that: children with abnormal spinal curveature will show impressive neuromuscular thightness ( like "short hamstrings") that will hinder easy postural balance. Car chairs are a curse for almost all human spines that loss form and function during the growth period.

In our clinic we start to use Diers Formetric scan ( surface topography) for the standing posture and will start research to compare this with the sitting postures on different seats ( chair, balls, Zami stool, saddles) but goniometers can give enough information. Kind regards.

I think you need to define the meaning of good body posture related to the specific activity performed. Then you need to limit what kind of instruments do you want to use to assess the variables you want to measure, such as EMG, force plate, etc. With regard to subjects, the difference due to race, age, sex, etc. are also very important. Basically, you will not be able to find the best posture for all of the population and for all the activities performed. There will be some trade-off.