Our product consists of a wheelchair mount, an enclosed box, a rotating platform, a tilting platform, and an adjustable camera mount.

 

The wheelchair mount uses a commercial wheelchair mounting clamp to hold the camera control system in a convenient position for the user. It is made from two steel tubes welded together a right angle, and a plastic platform. The platform is secured to the mounting tube assembly with conduit clamps, to allow angular adjustment of the base. The wheelchair mount is attached to the enclosed box with four screws.

 

The enclosed box is a clear acrylic plastic box that holds an electronics package, a continuous motion servo, a gear set, an on-off switch, and a joystick.

 

The electronics package consists of a battery, Arduino controller, and a circuit board. The battery is a commercially available 12 volt, 1500 milliamp rechargeable, lithium-polymer unit. It consists of three cells connected in series. The Arduino controller takes 4-bit commands from the joystick controller, and converts them into power commands for the servo and motor. These components are more fully described in the theory of operation.

 

The continuous motion servo is a commercially available (Hitech HS-311) unit that has been modified to run continuously. It has 48 inch-ounces of torque at 4.8 volts and runs at ~52 rpm at 4.8 volts.

 

The gear set consists of two laser-cut plastic gears approximately .25 thick. The smaller gear is attached to the servomotor shaft, and has 10 teeth. The larger gear is attached to the rotating platform, and has 40 teeth. Thus the gear set provides a speed reduction of 4:1 to the servomotor.

 

The joystick is a commercially available, 2-axis controller.

 

The rotating platform is fixed to the top of the base with a rotating ball bearing assembly. It has supports for the tilting platform, a shaft that mates with the first (4:1) gear set, and a motor that moves the tilting platform through a second gear set.

 

The rotating ball bearing assembly is a lazy susan turntable with a four inch by four inch rectangular base, and a 2-3/16 inch diameter hole through its’ center.

 

There are three tilt platform supports that are screwed to the rotating platform base, and provide room for the tilt platform movement, in addition to mounting spot for the tilt motor. A hole at the top of each support is used to hold the geared shaft that connects the rotating platform to the tilt platform.

 

The tilt electric motor is a 12 volt, one revolution per minute gear motor that provides 2,995 inch-ounces of torque. This high torque is needed to hold the tilt platform, camera mount, and camera in place when the motor is de-energized.

 

The motor gear is a 32 tooth brass gear with a 1.00 inch pitch diameter. It is secured to the six millimeter motor shaft with a set screw.

 

The tilting platform holds the camera mounting system, and connects to the tilting platform with a geared shaft that meshes with the motor gear.

 

The tilt platform is attached to the rotating platform with three blocks that are drilled to hold the geared shaft securely with set screws to the geared shaft. The tilt platform rotates about the axis formed by the geared shaft. The gear on the tilt shaft is identical to the gear on the motor, so the gear ratio is 1:1.

 

The camera mounting system is a commercial product that we slightly modified. We replaced a small lever that locks the camera mount ball with a larger one that is easier for a handicapped person to move. This system provides a quick release for the camera by means of a separate base that attaches to the camera through the mounting screw hole. It also gives a means of switching the camera from landscape to portrait orientation.