Need advice on motor control for Wheelchair Service project

Me, and a team of 3 others are working on an off-road electric wheelchair for a disabled man, and his family. The purpose of the chair is to allow his parents to continue to take him on walking trails. They are getting older, and pushing him on a manual wheelchair is becoming too difficult for them, but they can not afford to purchase an electric wheelchair. Unfortunately, no one in the group i am working with knows anything about how to get this thing moving properly, so I have decided to turn to those who might have experience with similar projects for help. Currently, we plan to purchase and use these motors to move the wheelchair

My current plan is to use an Arduino UNO to control the motors. While I understand i need some sort of speed controller to connect the arduino to the motors, i honestly have no idea what to look at.

Research done so far has shown me that i will need something that can provide a high enough current to both motors at the same time to be able to traverse obstacles, so the controller we choose needs to be capable of providing a high current. The motors run at 24v, and about 13Amps (calculated, not tested) under normal use, but need to be capable of much more for when the chair encounters obstacles.

It's also possible that everything i just said made no sense, so please feel free to ask questions if i did not make myself clear. Anything that can show me in the right direction would be appreciated. Anyone interested in the project can visit our fundraising page at Electric Assist Off-Road Wheelchair, organized by Joseph Farinella for more info.

I would suggest your first port of call is a visit to your local wheelchair service centre. Most towns or cities offer a community wheelchair user service and they will know who the local service firm is. Pay them a visit, tell them what you are trying to do and you might just be surprised as to how helpful they can be.

I certainly know my local one supplied me with sufficient "scrapped" chair salvaged pieces to build a complete control system. ie motors, wheels, controller, joystick and all interconnecting cables - all for a reasonable donation to their 'coffee' fund.

Definitely worth looking into, ill see whats around me tomorrow.

Some reading material that might be of use.

https://www.google.com/search?ie=UTF-8&oe=UTF-8&q=wheelchair&btnG=search&domains=http%3A%2F%2Fforum.arduino.cc&sitesearch=http%3A%2F%2Fforum.arduino.cc&gws_rd=ssl