**2. Modern wheelchair review**

With differing levels and causes of mobility impairment, this calls for upgraded wheel chair functions that can assist the users in performing standard tasks independently while minimising risk of contracting secondary diseases to the users. There is an increasing need for intelligent wheelchairs to elevate the user from seated to standing posture and vice versa as well as providing better flexibility of the user through improved manoeuvrability and increasing number of degrees of freedom (DoF) in terms of inclination of the chair.

**Reclining wheelchairs:** Also known as tilt-in-space wheelchairs, have seating platforms that can be tilted through various angles as shown in **Figure 1**. It allows the user to relax through different posture angles allowing blood flow to the lower limbs.

**Manually operated standing wheelchair:** The wheelchair uses bicycle chains to transfer power from tank tread-like push bars to the wheels or the system that lifts the user. It consists of a unique hand drive mechanism that allows users to drive the wheels of the wheelchair while seated, standing or in the range of positions in between (**Figure 2**).

Smart wheelchair: This typically consists of either a standard power wheelchair to which a computer and some sensors have been added or a mobile robot base to which a seat has been attached. Smart wheelchairs have been designed to provide navigation assistance to the user in a number of different ways, such as assuring collision-free travel, aiding the performance of specific tasks (e.g. passing through doorways), and autonomously transporting the user between locations. To avoid

**Figure 1.** *Reclining wheelchair [4].*

*Development of an Intelligent Standing Wheelchair with Reclining Characteristics DOI: http://dx.doi.org/10.5772/intechopen.96110*

**Figure 2.** *Manually operated standing wheelchair [5].*

**Figure 3.** *Electric powered standing wheelchair [7].*

obstacles, smart wheelchairs need sensors to perceive their surroundings. Proximity sensors are normally used to detect obstacles in the pathway of the wheelchair.

**Powered standing wheelchair:** This consists of an electric motor drive system powered by DC batteries mounted at the base of the frame. The speed of these motors is controlled by the remote control system to allow for forward, reverse and sideways propulsion of the wheelchair. On lifting the user, linear actuators and revolute motors (mounted at the back of the chair) are used to produce the required

#### *Paraplegia*

torque or control input signal from the remote control system to transform the shape of the wheelchair frame from seated to standing posture and vice versa [6]. The user is extended from a sitting position to a full standing position. The user's legs are locked and support the weight of the body at full extension. A hydraulic lift is used to complete the motion with elevation times ranging from 3 to 60 seconds (**Figure 3**).
