India has about 20 million people with disabilities out of which 11 million are locomotor disabled. in most cases, people with mobility impairments are restricted to using a wheel chair for a major part of their life. this usually means that the user needs assistance from another person to move over larger distances. the most extensively used wheel chair in india is a manually driven wheel chair. this however needs the user to have a considerable amount of upper limb strength to propel the wheelchair. this poses a major disadvantage especially when the user needs to move on an uneven terrain which requires additional muscle force. under such circumstances, a motorized wheel chair becomes necessary. although the wheelchair industry is deeply rooted and established, existing devices do not answer major challenges that users face in developing countries. in india, motorized wheelchair’s cost ranges from rs. 65,000/- to a whopping 3.7 lakhs, increasing with the functionality of the wheelchair. thus, one of the prime constraints is the cost of the motorized wheel chair. in addition to this, existing motorized wheelchairs pose several challenges to users including portability and weight (powered wheelchairs weigh more than 45kgs). a common trend seen in powered wheelchairs is the lack of modularity; they cannot be easily folded or disassembled. this makes it difficult to transport the wheelchair when not being used. most powered wheelchairs cannot be easily used when not powered. this prevents the usage of the wheelchair in manual mode which could be a major problem, in case of a power failure. these were the founding reasons for the project. to realize a potential product we wanted to improve on the above mentioned areas, most important of which being the cost. the major cost of the existing wheelchair is associated with the use of two motors and the required controllers and drivers, which provide for a differential drive. use of two motors also increases the weight of the device. hence, the proposed design focuses on using a single motor to power a motorized wheelchair. the direction is given through manual steering. this has been a major factor contributing to weight reduction. the device comprises a power unit and battery unit, both of which can be easily detached from the wheelchair when not used in powered mode. to ensure driving in manual and powered mode, the design uses a bldc motor which offers low resistance when engaged. the power unit consists of a brushless dc hub motor and a controller to provide for a variable speed drive. the drive train consists of a chain transmission for steering and the powered wheel is steered manually using a steering wheel. the steering wheel is attached to the power module though a detachable coupling. the device is so designed that it can be attached to existing manual wheelchair to convert it into a powered one. the wheelchair add-on has been designed keeping in mind the user comfort and the ease of maintaining the device in addition to the dynamic stability and the power requirements. features such as easy disassembly, compactness, low weight and most importantly low cost add enormous social and commercial value to the concept.