Types of Self Control Wheelchairs
Many people with disabilities utilize self-controlled wheelchairs to get around. These chairs are ideal for daily mobility and are able to overcome obstacles and hills. They also have large rear shock-absorbing nylon tires that are flat-free.
The speed of translation of the wheelchair was determined by using a local potential field method. Each feature vector was fed to a Gaussian encoder which output a discrete probabilistic spread. The evidence accumulated was used to control the visual feedback, and a command was delivered when the threshold was reached.
Wheelchairs with hand rims
The kind of wheel a wheelchair uses can affect its ability to maneuver and navigate different terrains. Wheels with hand-rims are able to reduce strain on the wrist and improve comfort for the user. Wheel rims for wheelchairs can be found in steel, aluminum or plastic, as well as other materials. They also come in various sizes. They can also be coated with vinyl or rubber for improved grip. Some are equipped with ergonomic features such as being designed to conform to the user's closed grip and having wide surfaces for all-hand contact. This allows them to distribute pressure more evenly and also prevents the fingertip from pressing.
A recent study revealed that flexible hand rims decrease impact forces and wrist and finger flexor activity when a wheelchair is being used for propulsion. They also provide a greater gripping surface than standard tubular rims allowing users to use less force while maintaining good push-rim stability and control. These rims are sold at a wide range of online retailers as well as DME suppliers.
The results of the study showed that 90% of respondents who had used the rims were happy with them. However it is important to keep in mind that this was a mail survey of those who had purchased the hand rims from Three Rivers Holdings and did not necessarily reflect all wheelchair users who have SCI. The survey did not measure any actual changes in the severity of pain or symptoms. It only assessed the extent to which people noticed an improvement.
The rims are available in four different styles including the light medium, big and prime. The light is an oblong rim with smaller diameter, and the oval-shaped large and medium are also available. The prime rims are also slightly larger in size and feature an ergonomically shaped gripping surface. These rims can be mounted on the front wheel of the wheelchair in a variety of colors. These include natural, a light tan, as well as flashy greens, blues, pinks, reds and jet black. These rims are quick-release, and are able to be removed easily for cleaning or maintenance. The rims are protected by rubber or vinyl coating to keep hands from sliding off and causing discomfort.
Wheelchairs with tongue drive
Researchers at Georgia Tech developed a system that allows users of a wheelchair to control other digital devices and maneuver it by moving their tongues. It is comprised of a small tongue stud that has magnetic strips that transmit movements signals from the headset to the mobile phone. The smartphone then converts the signals into commands that can be used to control a wheelchair or other device. The prototype was tested with able-bodied individuals as well as in clinical trials with patients with spinal cord injuries.
To evaluate the performance, a group physically fit people completed tasks that measured speed and accuracy of input. They completed tasks that were based on Fitts law, which included the use of mouse and keyboard, and a maze navigation task with both the TDS and the normal joystick. A red emergency stop button was built into the prototype, and a second was present to help users press the button if needed. The TDS worked just as well as a traditional joystick.
In another test that was conducted, the TDS was compared with the sip and puff system. This lets those with tetraplegia to control their electric wheelchairs through blowing or sucking into a straw. The TDS completed tasks three times more quickly, and with greater accuracy as compared to the sip-and-puff method. In fact, the TDS was able to operate wheelchairs more precisely than even a person with tetraplegia who controls their chair using a specially designed joystick.
The TDS was able to determine tongue position with an accuracy of less than one millimeter. It also included a camera system which captured eye movements of a person to detect and interpret their movements. It also came with security features in the software that checked for valid inputs from the user 20 times per second. If a valid signal from a user for UI direction control was not received for 100 milliseconds, the interface modules immediately stopped the wheelchair.
The next step for the team is to evaluate the TDS on people with severe disabilities. To conduct self propelled wheelchairs have partnered with The Shepherd Center which is a major care hospital in Atlanta and the Christopher and Dana Reeve Foundation. They are planning to enhance the system's tolerance to ambient lighting conditions and add additional camera systems and enable repositioning for alternate seating positions.
Wheelchairs with joysticks
A power wheelchair that has a joystick allows clients to control their mobility device without having to rely on their arms. It can be positioned in the middle of the drive unit or on either side. The screen can also be added to provide information to the user. Some of these screens are large and are backlit for better visibility. Some screens are smaller and contain symbols or pictures to aid the user. The joystick can also be adjusted to accommodate different sizes of hands grips, as well as the distance between the buttons.
As power wheelchair technology evolved, clinicians were able to create driver controls that allowed clients to maximize their functional potential. These advances allow them to accomplish this in a manner that is comfortable for users.
For instance, a standard joystick is a proportional input device which uses the amount of deflection in its gimble to produce an output that grows with force. This is similar to the way video game controllers and accelerator pedals for cars function. However, this system requires good motor function, proprioception, and finger strength to function effectively.
A tongue drive system is a second type of control that relies on the position of a person's mouth to determine the direction to steer. A magnetic tongue stud sends this information to the headset, which can perform up to six commands. It is a great option to assist people suffering from tetraplegia or quadriplegia.
Compared to the standard joystick, some alternative controls require less force and deflection in order to operate, which is especially helpful for users who have weak fingers or a limited strength. Others can even be operated by a single finger, which makes them ideal for those who are unable to use their hands in any way or have very little movement in them.
Additionally, certain control systems come with multiple profiles which can be adapted to the specific needs of each customer. This can be important for a novice user who might need to alter the settings periodically in the event that they experience fatigue or a disease flare up. This is useful for experienced users who wish to alter the parameters set for a particular setting or activity.
Wheelchairs with steering wheels
Self-propelled wheelchairs are made for people who require to maneuver themselves along flat surfaces and up small hills. They have large rear wheels for the user to grip as they move themselves. Hand rims enable the user to utilize their upper body strength and mobility to guide the wheelchair forward or backwards. Self-propelled wheelchairs are available with a range of accessories, including seatbelts that can be dropped down, dropdown armrests and swing away leg rests. Certain models can be converted to Attendant Controlled Wheelchairs, which permit family members and caregivers to drive and control wheelchairs for users who need more assistance.
Three wearable sensors were affixed to the wheelchairs of participants to determine kinematic parameters. These sensors tracked the movement of the wheelchair for the duration of a week. The gyroscopic sensors on the wheels and one fixed to the frame were used to measure the distances and directions of the wheels. To discern between straight forward movements and turns, the period of time during which the velocity differences between the left and right wheels were less than 0.05m/s was deemed straight. Turns were further studied in the remaining segments and turning angles and radii were calculated based on the wheeled path that was reconstructed.
The study included 14 participants. The participants were tested on navigation accuracy and command latencies. Using an ecological experimental field, they were required to navigate the wheelchair using four different waypoints. During the navigation trials sensors tracked the path of the wheelchair along the entire distance. Each trial was repeated at minimum twice. After each trial, participants were asked to select a direction for the wheelchair to move in.
The results revealed that the majority of participants were competent in completing the navigation tasks, even though they did not always follow the right directions. In average, 47% of the turns were completed correctly. The other 23% were either stopped immediately following the turn or wheeled into a subsequent turning, or replaced with another straight movement. These results are similar to those from previous studies.